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SPECUL CtMMISSOI H 
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NATIONAL SCIENCE FOUNDATION 




WEATHER 

AND 

CLIMATE MORAY 

Report of the 

SPECIAL COMMISSION ON 
WEATHER MODIFICATION 


NATIONAL SCIENCE FOUNDATION 








LETTER OF 
RANSMITTAL 


The Honorable Leland J. Haworth 
Director 

National Science Foundation 
Washington, D. C. 

Dear Dr. Haworth: 

It is an honor to transmit herewith 
to the National Science Foundation 
the report of the Special Commission 
on Weather Modification, authorized 
by the National Science Board at its 
meeting on October 17-18, 1963, in 
accordance with Sections 3(a)(7) and 
9 of the National Science Foundation 
Act of 1950, as amended, and 
appointed by you on June 16,1964. 

The Commission was requested to 
examine the physical, biological, legal, 
social, and political aspects of the field 
and make recommendations concern¬ 
ing future policies and programs. 

The physical science aspects have 
been studied primarily through 
cooperative liaison with the National 
Academy of Sciences’ Panel on 
Weather and Climate Modification. 


Much of the background work for the 
treatment of the other aspects of the 
problem was carried out under 
National Science Foundation grants or 
contracts, reports of which research 
and study are to be published as 
stated in the Appendix. 

The Commission held eleven 
meetings supplemented by many days 
of study, research, writing and 
conferences. The Commission report 
has been prepared by and its content 
is concurred in by all the members 
of the Commission. 

The Commission was assisted 
throughout its deliberations by an 
Executive Secretary. Dr. Edward P. 
Todd served in this capacity during 
the early months. Mr. Jack C. 
Oppenheimer succeeded Dr. Todd 
and has done an outstanding job of 
assisting the Commission. 

Respectfully submitted, 

A. R. Chamberlain, Chairman 

Vice President 

Colorado State University 


December 20, 1965 


in 



The Commission was established 
pursuant to Section 3(a)(7) and 9 of 
the National Science Foundation Act 
of 1950, as amended. 

The names and affiliations of the 
Commission members are: 

A. R. Chamberlain, Chairman 

Vice President , Colorado State University 

John Bardeen, Vice Chairman 
Departments of Physics and Electrical 
Engineering 
University of Illinois 

William G. Colman, 

Executive Director 
Advisory Commission on 
Intergovernmental Relations 

John C. Dreier 

School of Advanced International Studies 
The Johns Hopkins University 


Leonid Hurwicz 
Department of Economics 
University of Minnesota 

Thomas F. Malone, 

Second Vice President 
Research Department 
Travelers Insurance Company 

Arthur W. Murphy 
Columbia University School of Law 
Sumner T. Pike 
Lubec, Maine 
William S. von Arx 
Massachusetts Institute of Technology 
and Woods Hole Oceanographic 
Institution 

Gilbert F. White 
Department of Geography 
University of Chicago 

Karl M. Wilbur 
Department of Zoology 
Duke University 


SfECIU 

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ON 

HEATHER 

MOMHCIHON 


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LETTER OF TRANSMITTAL. iii 

SPECIAL COMMISSION ON WEATHER MODIFICATION .... iv 

HISTORICAL BACKGROUND . 1 

SUMMARY. 7 

Introduction . 7 

Scientific Possibilities. 11 

Biological Implications . 18 

The Social Effects. 20 

The Law . 23 

Needs and Opportunities for International Cooperation ... 26 

Fiscal and Organizational Considerations. 29 

PROGRESS AND PROSPECTS IN WEATHER AND CLIMATE 

MODIFICATION . 34 

Introduction. 34 

The Nature of the Scientific Problem . 34 

Present Status of Weather Modification. 38 

Accomplishments of the National Science Foundation 

Program . 43 

Activities in Foreign Countries. 47 

Perspectives for Research . 50 

Conclusions and Recommendations . 58 

BIOLOGICAL ASPECTS OF WEATHER MODIFICATION. 60 

Introduction. 60 

Means of Predicting Consequences of Weather Modifi¬ 
cation . 60 

Predicted Biological Responses of Weather Modifica¬ 
tion . 65 

Conclusions and Recommendations of The Ecological 

Society Working Group. 69 

STATISTICAL ASPECTS OF WEATHER MODIFICATION .... 71 

The Present Situation . 71 

The Conferences on Statistical Methodology. 71 

Conference Findings. 72 

Conference Recommendations . 73 


V 




























Precipitation-Oriented Experiments. 74 

The Empirical Approach. 75 

Numerical Modeling and Simulation. 76 

Commission Recommendations. 77 

Footnote . 79 

THE HUMAN EFFECTS OF WEATHER AND CLIMATE MODI¬ 
FICATION . 80 

Four Interlocking Systems . 82 

Uncertainty . 84 

Two Approaches to the Human Dimensions . 85 

Broader Considerations . 85 

Evaluating Social Effects . 86 

Conflicts of Interest. 90 

Desirable Courses of Action. 92 

Recommendations. 97 

Footnotes. 98 

LEGAL AND LEGISLATIVE ASPECTS . 100 

WEATHER MODIFICATION AND INTERNATIONAL RELA¬ 
TIONS . 113 

International Programs Related to Weather Modifica¬ 
tion . 115 

International Requirements of Research. 117 

Weather Modification and World Politics . 118 

Relation to IT. S. Foreign Policy. 119 

International Impact on U. S. Program. 120 

Organization of Inter-Governmental Cooperation .... 121 

Scientific and Technical Exchange. 122 

International Legal Problems. 122 

Questions of International Organization . 123 

Recommended Basic Policy Statement. 124 

FUNDING AND ADMINISTRATION REQUIREMENTS. 126 

Federal Financial Support of Weather and Climate Mod¬ 
ification . 126 

Administration . 130 

APPENDIX . 149 

vi 


































HISTORICAL 



Twenty years ago General Electric 
Company scientists Irving Langmuir 
and Vincent Schaefer modified clouds 
by “seeding” them with dry ice pel¬ 
lets. Not long afterward Bernard Von- 
negut, a co-worker, demonstrated that 
a smoke of silver iodide crystals 
would accomplish the same result. 
This was the beginning of the modern 
American history of weather and cli¬ 
mate modification through cloud 
seeding. 

These American scientists on No¬ 
vember 13, 1946, had verified experi¬ 
mentally the theory advanced in 1933 
by the Swedish meteorologist, Tor 
Bergeron, and the German physicist, 
Walter Findeisen, that clouds would 
precipitate if they contained the right 
mixture of ice crystals and super¬ 
cooled water drops. The Bergeron- 
Findeisen theory was antedated by 
the work of the Dutch scientist, Au¬ 
gust Veraart. The enthusiastic reports 
by Veraart of his 1930 experiments 
with dry ice and supercooled water-ice 
in Holland were not well received by 
the Dutch scientific community, and 
thus were given no serious considera¬ 
tion elsewhere. 

Weather and climate modification, 
or “rainmaking” (the more popular 
and also more restricted concept), is 


not new to our era or to our country. 
Many traditional societies, including 
the American Indians, have practiced 
some type of religious or ritualistic 
rainmaking. The ceremonials and rit¬ 
uals have varied from dousing holy 
men with water to burying children 
up to their necks in the ground in the 
hope that the gods would be sympa¬ 
thetic and drop tears from the heav¬ 
ens. These ceremonies are not only to 
induce some form of desirable weather 
but also to reinforce the tribal reli¬ 
gious beliefs and opinions which 
maintain social unity. 

Through ancient and modern times 
many methods have been proposed 
and attempted to induce or to aid 
rainfall. Two U. S. Government pat¬ 
ents on methods of rainmaking were 
issued before the turn of the 20th 
century based, respectively, upon the 
production of carbon dioxide by ex¬ 
pending “liquified carbonic acid gas” 
and upon concussion by the detona¬ 
tion of explosives. Interestingly 
enough the long since expired patent, 
based on the production of carbon 
dioxide in the form of dry ice, antici¬ 
pated the cloud seeders of today. The 
pioneering field and laboratory work 
of meteorologists in the War and Navy 
Departments on the popular notion 


1 



that rainfall could be caused by the 
detonation of explosives was sup¬ 
ported by Federal Government funds. 

Even social, political and legal con¬ 
flicts over weather and climate modi¬ 
fication are not new. In 1916 San 
Diego’s employment of a rainmaker, 
resulting in claims of loss of life and 
property damage of a million dollars, 
anticipated by half a century the liti¬ 
gation and State and local legislative 
action of today. 

The 1946 demonstration that clouds 
might be modified and rain produced 
by scientific methods arose out of the 
World War II investigations of fog 
particles by Langmuir and Schaefer. 
The military possibilities of this dis¬ 
covery led the armed services to sup¬ 
port a broad theoretical, laboratory 
and field program in cloud modifica¬ 
tion from 1947 to 1952, known as 
Project Cirrus. Civilian and military 
implications were investigated by the 
Cloud Physics Project of the U. S. 
Weather Bureau, Air Force and Na¬ 
tional Advisory Committee for Aero¬ 
nautics from 1948 to 1951. The mili¬ 
tary services followed the termination 
of Project Cirrus in 1952 with a De¬ 
partment of Defense 5 year Artificial 
Cloud Nucleation Project. 


Whether or not the multi-million 
dollar commercial rainmaking activi¬ 
ties of the late 1940’s and early 1950’s 
grew out of the obvious interest of the 
Federal Government in weather and 
climate modification research or the 
coincidental severe drought conditions 
in some parts of the nation, relatively 
vast operations became a fact of life. 
It was disclosed between 1951 and 
1953 in the Congressional Hearings 
leading up to the establishment of the 
Advisory Committee on Weather Con¬ 
trol that during the height of cloud 
seeding activities $3 to $5 million a 
year was being spent by water users, 
particularly in the West, for commer¬ 
cial cloud seeding, and that about 
107 c of the land area of the United 
States had become the target of cloud 
seeding attempts. 

The weather modification events of 
the late 40’s and early 50’s in the 
United States encouraged cloud seed¬ 
ing programs in Australia, France and 
South Africa to increase precipitation 
and renewed the scientific interest in 
hail suppression that had been prac¬ 
ticed in Alpine Europe since the mid 
30’s. The dozen nations experimenting 
with cloud seeding during the late 
1940’s more than doubled by 1951 to 



about 30 countries representing every 
continent. 

Meanwhile, the drought that held 
sway in many parts of the country, 
the claims of some of the rainmakers 
and the criticism from portions of the 
scientific community led the Congress 
to create an Advisory Committee on 
Weather Control to study and evalu¬ 
ate public and private experiments in 
weather modification. In its final re¬ 
port in 1957 the Advisory Committee 
on Weather Control found, among 
other things, on the basis of statistical 
evaluations, that cloud seeding in the 
mountainous areas of western United 
States of storms occurring during the 
cooler and moist winter and spring 
months produced an average increase 
in precipitation of 10 to 15 percent 
from seeded storms with a satisfac¬ 
tory degree of probability that the in¬ 
crease was not the result of natural 
variations in the amount of precipita¬ 
tion. On the basis of its physical eval¬ 
uations, the Committee found, among 
other things, that seeding from the 
ground with silver iodide generators 
is a valid technique for seeding clouds. 
As a consequence of these findings 
and their related scientific and tech¬ 
nical studies the Advisory Committee 
on Weather Control recommended: 


The development of weather 
modification must rest on a foun¬ 
dation of fundamental knowledge 
that can be obtained only through 
scientific research into all the phys¬ 
ical and chemical processes in the 
atmosphere. The Committee recom¬ 
mends the following: 

(1) That encouragement be 
given for the widest possible 
competent research in meteorol¬ 
ogy and related fields. Such re¬ 
search should be undertaken by 
Government agencies, universi¬ 
ties, industries, and other organi¬ 
zations. 

(2) That the Government spon¬ 
sor meteorological research more 
vigorously than at present. Ade¬ 
quate support is particularly 
needed to maintain continuity 
and reasonable stability for long¬ 
term projects. 

(3) That the administration of 
Government-sponsored research 
provide freedom and latitude for 
choosing methods and goals. Em¬ 
phasis should be put on sponsor¬ 
ing talented men as well as their 
specific projects. 

(4) That an agency be desig¬ 
nated to promote and support re- 



search in the needed fields, and 
to coordinate research projects. 
It should also constitute a cen¬ 
tral point for the assembly, eval¬ 
uation, and dissemination of in¬ 
formation. This agency should be 
the National Science Foundation. 

(5) That whenever a research 
project has the endorsement of 
the National Science Foundation 
and requires facilities to achieve 
its purpose, the agency having 
jurisdiction over such facilities 
should provide them. 

The above recommendations of the 
Advisory Committee on Weather Con¬ 
trol together with the 1957 report of 
the American Meteorological Society 
and the 1958 third report of the Com¬ 
mittee on Meteorology of the National 
Academy of Sciences emphasized the 
need for: fundamental knowledge; 
research; experimentation; education 
and training in meteorology and re¬ 
lated fields; promotion, support, co¬ 
ordination, evaluation and informa¬ 
tion assembly and dissemination by 
the National Science Foundation; and 
increased Federal support to universi¬ 
ties for basic research in the atmos¬ 
pheric sciences. 


4 


On July 11, 1958, the President ap¬ 
proved PL 85-510 which, in pertinent 
part, authorized and directed the Na¬ 
tional Science Foundation to: 

. . . initiate and support a pro¬ 
gram of study, research, and evalu¬ 
ation in the field of weather modi¬ 
fication, giving particular attention 
to areas that have experienced 
floods, drought, hail, lightning, fog, 
tornadoes, hurricanes, or other 
weather phenomena, and to report 
annually to the President and the 
Congress thereon. 

. . . consult with meteorologists 
and scientists in private life and with 
agencies of Government interested 
in, or affected by experimental re¬ 
search in the field of weather con¬ 
trol. 

. . . carry out the purposes . . . 
whether conducted by the Founda¬ 
tion or by other Government agen¬ 
cies or departments, . . . through 
contracts with, or grants to, private 
or public institutions or agencies, 
including but not limited to coop¬ 
erative programs with any State 
through such instrumentalities as 
may be designated by the governor 
of such State. 


Thus, for the last 7 1 /2 years the 
Foundation has been providing major 
support for the Federal Government’s 
weather modification program and 
also has been a focus for Govern¬ 
ment-wide program planning and 
coordination through various mecha¬ 
nisms, including its annual Interagency 
Conference on Weather Modification. 
During this same period, the Depart¬ 
ments of Agriculture, Commerce, 
Defense, and Interior have either ini¬ 
tiated or continued mission-oriented 
programs of research and develop¬ 
ment in weather and climate modifi¬ 
cation. These programs have been de¬ 
voted to such matters as research on 
the suppression of lightning-induced 
forest fires by the U. S. Forest service; 
observation, analysis and experimen¬ 
tal seeding of severe storms and hur¬ 
ricanes by the U. S. Weather Bureau; 
cloud physics research, experimental 
seeding of clouds and dispersal of 
clouds and fog by the military depart¬ 
ments; and research on reduction of 
water evaporation through use of 
chemical films and increase of water 
supplies through research and experi¬ 
mental seeding by the U. S. Depart¬ 
ment of the Interior. 

The FY 1966 total annual spending 
for all the various Federal agency 


programs of weather modification re¬ 
search and development is about 7.2 
million dollars. During the year end¬ 
ing June 30, 1965, there were 59 cloud 
seeding projects by 15 commercial 
operators concerning operations in 26 
different states. At present there are 
research activities reported from 15 
foreign nations. 

In November 1963, in response to 
increased concern over the potentiali¬ 
ties for man-made changes of weather 
and climate and the interest in under¬ 
taking large scale weather modifica¬ 
tion activities, the Committee on At¬ 
mospheric Sciences of the National 
Academy of Sciences (NAS) appointed 
a Panel on Weather and Climate Mod¬ 
ification “to undertake a deliberate 
and thoughtful review of the present 
status and activities in this field, and 
of its potential and limitations for the 
future.” On June 16, 1964, the Direc¬ 
tor of the National Science Founda¬ 
tion announced the appointment of 
the Special Commission on Weather 
Modification, as previously authorized 
by the National Science Board at its 
89th Meeting on October 17-18, 1963. 
The Commission was assigned to: (1) 
fulfill the need of the National Science 
Foundation for a review of the state 
of knowledge on weather and climate 



modification, make recommendations 
concerning future policies and pro¬ 
grams and examine the adequacy of 
the Foundation’s program; and (2) 
respond to the request of the Inter¬ 
departmental Committee for Atmos¬ 
pheric Sciences of the Federal Coun¬ 
cil for Science and Technology of 
August 19, 1963 to prepare an analy¬ 
sis of the modification and control of 
the weather for useful purposes other 
than military. The Commission’s as¬ 
signment included consideration of 
not only the scientific aspects but also 
the legal, social and political prob¬ 
lems in the field. 

In view of the broad categories of 
questions directed to the Commission 
by the National Science Foundation, 
the Commission activated seven sub¬ 
groups, each of which was headed by 
one or more members of the Commis¬ 


sion. The physical, biological, statisti¬ 
cal, social, international, legal and 
legislative, and administration and 
funding aspects have been studied by 
these sub-groups. The physical sci¬ 
ence aspects have been studied pri¬ 
marily through cooperative and con¬ 
tinuing consultation and liaison with 
the National Academy of Sciences’ 
Panel on Weather and Climate Modi¬ 
fication. Much of the background 
work for the treatment of the various 
aspects of the problem was carried 
out under National Science Founda¬ 
tion grants or contracts. Reports of 
these research and study activities 
are to be published as stated in the 
Appendix. The National Academy of 
Sciences has just completed its final 
report, entitled Weather and Climate 
Modification — Problems and Pros¬ 
pects, Vols. I and II. 



INTRODUCTION 

Man is becoming so numerous and 
his influences on his environment so 
profound that he cannot consider him¬ 
self free to heedlessly or improvi- 
dently exploit the air, water, land, and 
growing things of this earth. He no 
longer lives under the constant threat 
of a wilderness but, instead, is chang¬ 
ing his environment and, therefore, 
must plan for its conservation and 
development. 

With advances in his civilization 
man has learned how to increase the 
fruit of the natural environment to in¬ 
sure a livelihood. The main problems 
which now threaten his future are: 

1) large-scale, catastrophic war¬ 
fare; 

2) providing sustenance for a rap¬ 
idly increasing population; 

3) waste disposal and environ¬ 
mental change accompanying 
the discharge of matter into the 
atmosphere, open waters, and 
subterranean spaces. 

Recognizing these circumstances of 
human activity, it is fortunate that 
growing knowledge of the natural 
world has given him an increasing 


awareness of the changes that are 
occurring in his environment and also 
hopefully some means for deliberate 
modification of these trends. An ap¬ 
praisal of the prospects for deliberate 
weather and climate modification 1 can 
be directed toward the ultimate goal 
of bringing use of the environment 
into closer harmony with its capaci¬ 
ties and with the purposes of man— 
whether this be for food production, 
relief from floods, assuring the con¬ 
tinuance of biologic species, stopping 
pollution, or for purely aesthetic rea¬ 
sons. 

The National Science Foundation 
Special Commission on Weather Modi¬ 
fication was asked to consider one 
aspect of the problem of environ¬ 
mental conservation and utilization. 
With the physical possibility of modi¬ 
fying the weather and climate already 
partly demonstrated, it is important to 
inquire: How by artificially inducing 
deliberate changes in the environment 
may man act to control or develop 

1 Throughout this report the term “weather 
and climate modification” is taken to mean 
artificially produced changes in the compo¬ 
sition, motion, or dynamics of the atmos¬ 
phere, whether or not such changes may be 
predictable, their production deliberate or 
in advertent, or their duration transient or 
permanent. 


7 


changes in the atmosphere considered 
to be desirable by society? With this 
question in mind, the Commission has 
concerned itself with the physical, bio¬ 
logical, social, engineering and legal 
aspects of weather and climate modi¬ 
fication. 

Weather and climate modification 
is becoming a reality. The daily activi¬ 
ties of man influence the atmosphere 
in a number of ways and his ability 
to induce deliberate changes in meas¬ 
urable magnitude by artificial means 
is progressing. The scale of known 
operational ability for deliberate rou¬ 
tine weather modification is presently 
the dissipation of supercooled fog and 
stratus over an area approximately the 
size of an airport, for a short period 
of time. On a larger scale, the inad¬ 
vertent modification of the weather 
and climate by such influences as the 
products of urban development, sur¬ 
face modification for agriculture and 
silviculture, compositional changes 
through the combustion of fossil fuels 
and other exhausts are becoming of 
sufficient consequence to affect the 
weather and climates of large areas 
and ultimately the entire planet. 

Deliberate modification of weather 
and climate may be accomplished by 


not only artificially influencing the 
atmosphere but by controlling inad¬ 
vertent changes. For example, smog 
is the result of deliberate pollution 
which causes inadvertent modification 
of urban weather and climate. A num¬ 
ber of questions are involved: 

1. If deliberate modification of the 
atmospheric environment is already 
a growing physical possibility, what 
are the scientific prospects for the 
future? 

2. What may be the biological con¬ 
sequences of weather and climate 
modification activities? 

3. What might be the social, human 
and economic benefits to man? 

4. Are there legal, political and 
legislative issues to be resolved? 

5. How should the plans of the 
United States in weather and climate 
modification be communicated to and 
coordinated with other nations? 

6. What are the organizational and 
funding needs for a national program 
in weather and climate modification? 

These questions are explored in 
some detail in the body of the report. 
Summarized here are some of the Com¬ 
mission’s findings and conclusions 
relevant to these questions. 



Scientific Prospects 

1. Several cubic miles of super¬ 
cooled cloud droplets can be trans¬ 
formed into ice crystals by seeding 
with dry ice or silver iodide. Super¬ 
cooled fog on the ground can be dissi¬ 
pated. No practical approach to the 
dissipation of warm fog is at hand. 

2. While the evidence is still some¬ 
what ambiguous, there is support for 
the view that precipitation from some 
types of clouds can be increased by 
the order of ten percent by seeding. 
If the results are confirmed by further 
studies they would have great signifi¬ 
cance. The question of corresponding 
decreases of precipitation outside the 
target area is unresolved. 

3. Results from attempts to sup¬ 
press hail in the United States are as 
yet inconclusive but more promising 
results in other countries are leading 
to the establishment in this country 
of a program that should provide a 
more definitive answer. 

4. Experiments in lightning sup¬ 
pression are beginning to show some 
promise. 

5. Modification of hurricanes has 
reached the stage of preliminary field 


experimentation but the results, so far, 
are inconclusive. 

6. Changing the course or intensity 
of extratropical cyclones and altering 
climate over large areas remain as 
problems for the future. No serious 
attempt has yet been made to control 
tornadoes. 

7. Inadvertent changes in climate as 
a consequence of human activity (e.g., 
urbanization, air pollution, increase of 
atmospheric carbon dioxide by burm 
ing fossil fuels] are amenable to analy¬ 
sis and deserve early attention. 

With respect to the scientific pros¬ 
pects for the future, the Commission 
finds that attractive opportunities exist. 
Advanced experimental techniques 
and application of sophisticated con¬ 
cepts in statistical design promise to 
reduce the present uncertainty in the 
interpretation of field experiments. 
The scientific exploration of weather 
and climate modification is passing 
from the speculative phase to the 
rational phase. Within reach are 
mathematical and laboratory modeling 
techniques that permit the simulation 
of atmospheric processes. By these 
means it should become possible to 
assess in advance the probable con¬ 
sequences of deliberate intervention. 



An expanded program of basic and 
applied research is needed to take 
advantage of these scientific oppor¬ 
tunities. 

Biological Consequences 

Great uncertainty has been encoun¬ 
tered regarding the biological conse¬ 
quences of weather and climate modi¬ 
fication. Augmentation of rainfall over 
cultivated areas could partially allevi¬ 
ate the increasing problem of food 
production. However, there is an ac¬ 
companying possibility that instabili¬ 
ties might result in the balances of 
biological communities. Such imbal¬ 
ances can be expected in the diseases 
and pests of man’s domesticated plants 
and animals. In small areas of natural 
communities it is possible that some 
wild species may be severely stressed. 
The timing of the atmospheric inter¬ 
vention relative to the reproductive 
cycle of the various species in the 
community may be of more impor¬ 
tance than the magnitude of the inter¬ 
vention. Both field and simulation 
studies of these biological relation¬ 
ships are needed before, during and 
after sustained operational programs. 
These studies should help avoid un¬ 


desirable, unanticipated and irrevers¬ 
ible ecological changes. 

Special implicaiions 

Weather and climate are among the 
major determinants of economic and 
social activity. Any change in pre¬ 
cipitation, temperature, and wind— 
whether deliberate or inadvertent—is 
likely to have a significant effect upon 
society. Although a number of tech¬ 
niques are available for the study of 
the economic and social impact of 
weather modification, relatively little 
has been done. Much remains to be 
learned of the manner in which man 
responds to the normal variability in 
weather conditions. Relatively little is 
known of the processes of decision¬ 
making in human activities in relation 
to present day weather prediction. 
Economic and social analysis of these 
relationships is urgently required as 
an aid in developing and applying 
techniques of weather and climate 
modificiation. If the developing tech¬ 
niques of weather and climate modi¬ 
fication are to be used intelligently, 
the human consequences of deliberate 
or inadvertent intervention need to be 
anticipated before they are upon us. 


10 




Weather and climate modification 
poses legal questions as to the exist¬ 
ence of “property” interests in weather 
and the responsibilities of weather 
modifiers for damage to others, as well 
as problems of regulation. It is too 
early to make specific suggestions as 
to the law which should govern “prop¬ 
erty” in weather, or the liabilities of 
weather modifiers. However, recom¬ 
mendations are made as to needed 
regulation and indemnification of those 
working on government supported 
programs. 

internMl Relations 

The Commission finds far-ranging 
international implications in weather 
and climate modification. By its very 
nature weather transcends national 
boundaries. An attractive opportunity 
exists to anticipate the effect of tech¬ 
nological development in weather and 
climate modification upon interna¬ 
tional relations. Specific steps are 
recommended to foster international 
cooperation in research and in the 
peaceful use of any physical capability 
that may evolve. 


omiMn and Ms 

The national program should involve 
basic research, technology, operations 
and regulation. There needs to be 
assigned to a single existing govern¬ 
ment agency, or to a completely new 
agency, the responsibility for develop¬ 
ing the technology of weather and 
climate modification. The National 
Science Foundation should continue 
and expand its support of research 
in the atmospheric sciences, including 
its program directed at providing a 
satisfactory scientific basis for weather 
and climate modification. Other gov¬ 
ernmental agencies should undertake 
such research and operational activi¬ 
ties in weather and climate modifica¬ 
tion as their missions may require. 

Federal financial support for re¬ 
search and development activity in 
weather and climate modification 
should be increased several fold over 
present levels. 

SCIENTIFIC POSSIBILITIES 

In pursuing means to modify weather 
and climate man assumes the charac¬ 
ter of a force of nature. That state is 
not at all novel in that man by inad- 


11 



vertent acts has already modified some 
aspects of weather and climate through 
urban development, surface changes 
for agriculture, forest culture and 
flood control, and altered the compo¬ 
sition and thus the radiation balance 
of the atmosphere through the com¬ 
bustion of fossil fuels. Deliberate 
alteration of the atmospheric regimen 
is, however, a new concept. Thus far 
the brightest hope for deliberate inter¬ 
vention lies in the possibility of alter¬ 
ing precipitation rates and dissipating 
supercooled fog by silver iodide or dry 
ice seeding. This has caused the pros¬ 
pect of weather and climate modifica¬ 
tion to be viewed mainly in the light 
of these techniques and their attend¬ 
ant geographic scales. 

If it is granted that the possibility 
of successful use of seeding procedures 
is a real one, it must also be recog¬ 
nized that it is in the character of 
modern man that he will press on to 
develop larger scale measures; some 
of which are already in the conceptual 
stages of evolution. For this reason, 
planning for research in weather and 
climate modification must be broad 
enough at its very outset to accommo¬ 
date future progress toward large scale 
or manifold activities. Moreover, judg¬ 
ment of sound action must be based 


on a suitably broad foundation of in¬ 
formed scientific, economic, legal and 
other opinion, with a clear appraisal 
especially of the biological and eco¬ 
logical risks involved. 

There are four needs to be met in 
weather and climate modification: 

1. To assess and understand natural 
climatic change. 

2. To assess and understand the 
inadvertent changes in weather and 
climate that the technological evolu¬ 
tion of man has produced; 

3. To improve man’s ability to pre¬ 
dict the behavior of the atmosphere 
so that he may arrange his affairs with 
a minimum of danger or surprise; and 

4. To devise a variety of techniques 
for deliberate intervention in the 
course of atmospheric (or other] proc¬ 
esses which will alter weather and 
climate in the interest of mankind. 

Why attention to the field is timely 
is well explained in the Introduction 
to Vol. I of the Report of the Panel on 
Weather and Climate Modification of 
the National Academy of Sciences. 1 

1 Weather and Climate Modification— 
Problems and Prospects, Vols. I and II, Na¬ 
tional Academy of Sciences-National Re¬ 
search Council, 1966 (NAS-NRC 1350). Vol¬ 
ume II contains an extensive bibliography. 


12 



One might ask why so detailed a 
survey of the status and outlook of 
atmospheric modification as we have 
made should be undertaken at this 
time. During approximately the past 
decade, subtle but significant shifts 
have occurred in long-term prospects 
for weather and climate modification; 
in many fundamental respects, an 
earlier era of speculation had grad¬ 
ually been superseded by the present 
period in which rational and syste¬ 
matic exploration of modification po¬ 
tentialities has become possible. Sev¬ 
eral changes stand out as factors 
causing this shift: 

(1) Formulation of increasingly com¬ 
plete and elaborate theories of atmos¬ 
pheric processes has advanced to a 
state in which moderately realistic 
mathematical models can be con¬ 
structed for a variety of atmospheric 
systems ranging in scale from micro- 
meteorological to global. Admittedly 
crude and rudimentary in many in¬ 
stances, such models constitute a 
necessary first step in reducing the 
degree of empiricism that has charac¬ 
terized most past speculations con¬ 
cerning atmospheric modification. 

(2) Prior to about 1950, such mathe¬ 
matical models were for the most part 


unproductive because of the sheer 
mathematical complexity of the sys¬ 
tems of equations constituting the 
models. The advent of high-speed 
automatic computers has, within the 
past decade or so, radically altered 
this picture. Computing speeds and 
storage capacity have risen by many 
orders of magnitude, and a growing 
body of investigators in the atmos¬ 
pheric sciences has seized this power¬ 
ful new tool to use it in analyzing 
critical aspects of the physics of our 
atmosphere. The important practical 
goal of improved numerical weather 
prediction became a stimulus that has 
recently led many workers to con¬ 
duct increasingly elaborate computer 
studies in the broad area of numerical 
experimentation. Today, numerical 
simulation, albeit impressively com¬ 
plex and varied in scope, is almost 
certainly only a primitive first step 
toward future levels of understanding 
of the subtle and highly interdepend¬ 
ent workings of our atmosphere; but 
it is a beginning with foreseeably pro¬ 
found implications for weather modi¬ 
fication. This development alone is 
significant enough to justify a new and 
deeper examination of modification 
prospects. 


13 



(3) Man's ability to measure and to 
observe the atmosphere with its myriad 
parameters has been growing steadily. 
Two decades of improvement in use 
of aircraft as measurement platforms, 
two decades of elaboration of radar- 
meteorological techniques, and soon 
a full decade of experience with the 
incomparable synoptic observing capa¬ 
bilities of the meteorological satellite, 
combine with many other advances 
in instrumentation and observation 
systems to permit almost entirely new 
dimensions in man's ability to keep 
track of the rapid changes that are so 
characteristic of weather. Clearly, still 
further improvements may be expected 
in the future, but one senses that 
already we have available the meas¬ 
urement skills requisite to monitoring 
adequately many of these atmospheric 
systems we seek to modify. 

The three considerations discussed 
above are of sufficient basic impor¬ 
tance to prospects for present and 
future weather modification that, even 
without the particular stimulus of cur¬ 
rent advances in cioud modification 
per se, it would be most timely to 
undertake a survey of the field of 
atmospheric modification. 


Much of the present effort in weather 
modification stems from the sugges¬ 
tion in 1946 of Langmuir and Schaefer 
that precipitation could be enhanced 
by introduction of ice, or ice-like 
nuclei, into clouds. The basis for the 
suggestion is that condensation of 
water droplets into particles large 
enough to fall may occur by growth 
of ice crystals in supercooled parts of 
the cloud. Water droplets may be 
supercooled well below the freezing 
point unless freezing nuclei are pres¬ 
ent. If clouds lack a sufficient number 
of natural nuclei, precipitation could, 
according to the theory, be enhanced 
by introduction of artificial nuclei into 
the appropriate parts of the cloud. In 
subsequent years the many experi¬ 
ments done in this country and abroad 
to test the theory have led to inclusive 
and controversial results. It has only 
been during the past year, largely as 
a result of a thorough analysis of 
available data by the NAS Panel on 
Weather and Climate Modification, 
that statistical evidence, although still 
somewhat ambiguous, appears to show 
that precipitation can be modestly 
enhanced locally by seeding. 

Most of the experiments on which 
this conclusion is based are of an 
empirical nature. Typically nuclei are 


14 



introduced by ground-based silver 
iodide generators. Rainfall is meas¬ 
ured in a target area extending per¬ 
haps 30 to 50 miles downwind and 
also in a control area upwind from 
the generators. By comparing the ob¬ 
served rainfall during the seeding 
operations in the two areas with aver¬ 
ages over past years, one can estimate 
the increase, if any, caused by seeding. 
In some cases the seeding is done on 
a randomized basis and a comparison 
is made between seeded and unseeded 
days and areas. Because of the wide 
variability of cloud systems, a great 
deal of data is required to obtain sta¬ 
tistically significant results and also to 
ascertain under what conditions and 
what geographical locations seeding 
may be effective. The possibility of 
some sort of systematic error or bias 
must be eliminated by statistical 
design. 

There is need for more empirical 
studies carefully designed to deter¬ 
mine how effective seeding is in in¬ 
creasing rainfall or in suppressing hail 
and lightning in various situations. 
These experiments should be designed 
to give reliable and statistically sig¬ 
nificant data. 

Toward this end a program of 
planned field experiments should be 


undertaken which provide continuity 
over a period of 5 to 10 years on a 
sufficient scale to permit geographic 
comparisons and differentiation, as 
well as stratification according to the 
type of seeding agent, mode of injec¬ 
tion, cloud type, etc. Provision should 
be made for the inclusion of relevant 
precipitation data in addition to other 
relevant physical variables. This pro¬ 
gram should be designed and evalu¬ 
ated in close association with statis¬ 
ticians with extensive experience in 
experimental design. 

Another approach is through basic 
research on cloud physics. These 
studies have shown that cloud sys¬ 
tems are extremely complex and that 
precipitation can probably occur in a 
number of ways. There is only a rudi¬ 
mentary knowledge of how the arti¬ 
ficially induced nuclei enter the clouds 
and how precipitation is actually 
affected. Thus, there is a wide gap 
between the basic research studies 
and cloud physics and an understand¬ 
ing of the empirical results of seeding. 

In order to optimize seeding proce¬ 
dures and to better assess their inher¬ 
ent limitations, much more must be 
learned about the actual physical 
mechanisms involved. This requires 
more elaborate and expensive field 


15 



experiments in which a number of 
variables are measured in addition to 
over-all precipitation, or, in the case 
of hail studies, the amount and nature 
of the hail. 

A number of suggestions have been 
made of possible methods to produce 
changes in the climate extending over 
large areas. It is known that rather 
abrupt changes in climate have oc¬ 
curred in the historical past, but there 
is as yet little understanding of the 
factors which brought them about. It 
is possible that changes in climate 
may also be produced inadvertently 
by activities of man. To assess the 
probable consequences of both delib¬ 
erate and inadvertent changes requires 
much better knowledge than is now 
available of the general circulation of 
the atmosphere and oceans, sources 
and sinks of heat, and energy inter¬ 
changes at the surface of the earth. 
To acquire such knowledge will re¬ 
quire many years of basic research. 
Man is now learning how to simulate 
the atmosphere numerically with use 
of large digital computers and by use 
of laboratory models. It has been esti¬ 
mated that computers two orders of 
magnitude faster than those now in 
use will be required for adequate 
simulation of the atmosphere on a 


global scale for general circulation and 
on a limited scale for local storms. 
A broad research program of this sort 
is required and can be justified for aid 
in long-range forecasting. Its impor¬ 
tance for making possible predictions 
of consequences of deliberate and 
inadvertent modifications of climate 
gives it added justification. 

Computer simulation and other 
studies should include a search for 
triggering mechanisms and means for 
suppressing violent but marginally sus¬ 
tained extremes in weather. Further 
development of laboratory and com¬ 
puter simulation should also yield 
insights crucial to the design of field 
experiments, to systematic efforts to 
modify weather and to long-range 
international planning of non-atmos- 
pheric methods of weather and cli¬ 
mate modification. 

It is assumed that the mission-ori¬ 
ented programs already underway, 
such as that of the Department of 
Interior to attempt to increase precipi¬ 
tation over its Reclamation project 
watershed areas and those of the De¬ 
partments of Agriculture, Commerce 
and Defense will be continued in both 
their scientific engineering and opera¬ 
tional phases. These present experi¬ 
ments should be continued. But, it is 


16 



essential that there be an increase of 
effort, either by agencies of govern¬ 
ment or by academic and other groups 
to insure that the biological, legal, 
social and statistical aspects of the 
experiments are given sufficient atten¬ 
tion. Present mission-oriented field 
experiments are examples of work 
undertaken despite the fact that there 
has been insufficient fundamental re¬ 
search. If large-scale field seeding 
activities are properly designed and 
controlled and can be supported by 
adequate ecological investigations, 
with monitoring and associated funda¬ 
mental research, there is no question 
that such experiments will yield knowl¬ 
edge benefiting weather modification 
research while the public policy objec¬ 
tive of attempting to increase precipi¬ 
tation over the watersheds is being 
pursued. 

One can conceive of non-atmos- 
pheric possibilities for deliberate 
weather and climate modification 
which could lead to major changes in 
climate. An example is possible altera¬ 
tion of the oceanic heat balance by 
lifting cold water to the surface in 
major currents such as the Gulf Stream 
or Kuroshio (Japan) Current. Such ex¬ 
periments should obviously not be 
undertaken without many years of in¬ 


ternational study of all consequences. 
But, the increasing levels of energy 
available to man are even now so 
great that such proposals may be 
entertained. 

To carry out the necessary labora¬ 
tory, field and theoretical research for 
a full understanding of atmospheric 
and non-atmospheric weather and cli¬ 
mate modification and inadvertent 
changes in weather, will require the 
efforts of people well qualified in dis¬ 
ciplines such as applied physics, engi¬ 
neering, chemistry, statistics and mete¬ 
orology, as well as biology, geology, 
oceanography, mathematics and hy¬ 
drology. 

In the view of the Commission, 
some of the greatest future needs of 
the physical sciences and engineering 
in weather and climate modification 
research and development are: en¬ 
hancement of the support of funda¬ 
mental research looking to creative 
ideas; much greater logistics capability 
for supporting large-scale experiments 
whether over sea or land; careful atten¬ 
tion to the statistical design of experi¬ 
ments; a larger program in computer 
simulation and laboratory geophysical 
modeling; and consideration of syn¬ 
chronous satellites for observing the 
life history of storms such as hurri¬ 
canes. 


17 



BIOLOGICAL IMPLICATIONS 

Man is an organism directly de¬ 
pendent on other organisms for many 
of his materials. He also struggles 
with other organisms, most of them 
quite small, that prey upon him, eat 
his food, or otherwise challenge his 
existence. Anything that has a general 
and significant effect upon plants and 
animals, making some more abundant, 
others less so, is of primary concern 
to mankind, for it strikes at the very 
basis of human existence. Changes in 
weather and climate may be expected 
to have such effects. It follows that 
any program of weather and climate 
modification must give serious atten¬ 
tion to adverse as well as beneficial 
biological aspects. 

It must be recognized that the pres¬ 
ent state of knowledge places uncom¬ 
fortable demands on the prediction of 
the biological consequences of modi¬ 
fying the weather. Prediction of the 
impact of weather modification on the 
biological components in man’s arti¬ 
ficial ecological systems such as his 
cities and his farms will probably be 
easier to attain than such prediction 
for the more nearly wild areas. This 
is so, because economic objectives 


have insured more adequate biological 
information concerning artificial sys¬ 
tems, and because these systems are 
not so complex biologically. It is es¬ 
sential that this present primitiveness 
in our biological forecasting capability 
not be used as an argument for omit¬ 
ting it from weather modification pro¬ 
grams. 

Prediction of the types and degrees 
of change in crop and livestock yield 
and quality to be expected from spe¬ 
cific changes in weather sequences 
can be markedly improved with meth¬ 
ods and analyses already at hand. 
Prediction of the direct effects of 
weather changes on the domesticated 
organism can be attained more 
quickly than prediction of the indirect 
effects resulting from weather-in¬ 
duced changes to the domesticants’ 
parasites, diseases, pests and symbi- 
ants. The published literature contains 
many references to studies implicat¬ 
ing unusual weather sequences for 
disease and insect and weed out¬ 
breaks. Vector-born diseases of plants 
and animals, humidity-responsive bac¬ 
terial and fungal diseases of crops and 
many insect outbreaks can be cited as 
examples. A fuller knowledge of these 
inter-relations coupled with a capabil¬ 
ity of highly accurate control over the 


18 



weather could have favorable eco¬ 
nomic results. Ignorance concerning 
the biological consequences to be ex¬ 
pected from significant changes in the 
weather could be locally detrimental. 

In wild lands the complex natural 
arrays of organisms are in delicate 
adjustment not only with the normal 
climate but also with the pattern of 
fluctuations. On the basis of the few 
published long-term studies in which 
biological composition has been fol¬ 
lowed during major weather fluctua¬ 
tions, it seems a reasonable prediction 
that alterations in weather patterns 
are likely to constitute at least a tem¬ 
porary unstabilizing influence in most 
natural biological communities. It is 
important to note that weather and 
climate fluctuations have been a mold¬ 
ing influence on natural populations 
and most species have adaptations re¬ 
lating to it. Thus, weather and climate 
modifications need not constitute 
changes exceeding the recorded ex¬ 
tremes in order to cause significant 
biological consequences. Some of the 
successional species that tend to in¬ 
crease during instability may be eco¬ 
nomically important species such as 
the succession of many forest species. 
Since many pests are also favored 


during instability, the net economic 
effect is difficult to predict. 

In vast reaches where the biological 
communities extend beyond the areas 
of weather modification it can be ex¬ 
pected that natural migrations of 
species from areas adjacent to the 
changed condition will tend ulti¬ 
mately to restore stability. However, 
in the small islands of natural bio¬ 
logical communities such as parks and 
preserves the effects will be less apt 
to set themselves right. The wide 
stretches of man’s artificial biological 
make-up and disturbance between 
such islands provides an effective bar¬ 
rier to migrations. Extinction, at least 
locally, could result for some species. 

Thus, from the present crude state 
of the field, one can roughly predict 
that the biological outcomes of 
weather modification are apt to be a 
mixed bag of economically good and 
bad effects in man’s artificial ecosys¬ 
tems. It is difficult to visualize any 
desirable effect on the small preserves 
of natural communities. In order to 
improve biological forecasting several 
avenues are open: 

1. Growth chamber simulation of 
such changes on as large a fragment 
of the biological type as possible. 


19 



2. Examination of areas biologically 
and climatically analogous to the 
changed and unchanged situations. 

3. Study of the fine structure in the 
fossil record of the recent past. 

4. Computer simulation of changes 
using the best available data. 

5. Monitoring of sample areas 
within and outside of regions sub¬ 
jected to weather modification. The 
monitoring should begin before 
weather modification activities and 
extend beyond their cessation. 

It is the position of the Commission 
that there should be a strong effort 
to bring the field of biological fore¬ 
casting up to a higher level of useful¬ 
ness. This is mandatory in planning 
weather and climate modification over 
areas involving more than a few hun¬ 
dred square miles. 

A by-product of such expanded re¬ 
search and development will have 
wide utility in agriculture, forestry 
and park and general resource man¬ 
agement and other fields. Beyond this, 
as an area of fundamental science, 
forecasting of the behavior of eco¬ 
logical systems needs to be augmented 
since man knows so very little about 
how such systems operate, either the 
man-made ones that sustain him or 


the natural ones from which he de¬ 
rives an essential part of his inspira¬ 
tion and contentment. 

All five of the above approaches 
need to be brought to bear on the 
problem. Any group involved with 
large-scale experimentation with 
weather modification should be ex¬ 
pected to provide for adequate bio¬ 
logical monitoring. The team effort 
that would result from this kind of 
interaction of meteorologists, hydrolo¬ 
gists, engineers, ecologists, agrono¬ 
mists, foresters, entomologists, etc. is 
long overdue. 

THE SOCIAL EFFECTS 

Weather and climate conditions are 
among the major determinants of eco¬ 
nomic activities and social structure. 
No other aspect of the environment 
has as many pervasive relations to 
the pattern of human activity on the 
globe. Any substantial change in pre¬ 
cipitation, temperature, or wind, 
whether deliberate or inadvertent, is 
likely to have a significant effect upon 
society, as the public and private ex¬ 
penditures for hurricane, drought, and 
flood disasters dramatically illustrate. 
The immense varieties of housing and 


20 




of farm cropping practices illustrate 
less obvious but fundamental adjust¬ 
ments to weather and climate. In some 
cases the influence of weather and 
climate modification on human activ¬ 
ities may result in shifts of the social 
institutions that are too subtle to be 
recognized by many of those involved. 

If scientific research in changing 
weather and climate is regarded as 
an investment decision, society should 
seek answers to several questions as 
it decides how much to spend for 
what kinds of research. Who benefits 
from the investment if made? If both 
benefits and losses occur, how are 
they distributed? Will the normal 
market forces provide enough incen¬ 
tive to achieve the socially optimum 
results to mankind? 

It does not seem plausible that pri¬ 
vate enterprise will finance research 
at a level adequate to achieve the 
optimum social objective. Further, 
because the benefits or losses do not 
necessarily accrue to people in the 
same geographic area or in the same 
businesses, weather and climate modi¬ 
fication research needs to be sup¬ 
ported primarily from federal sources 
for the foreseeable future. This posi¬ 
tion is to be expected when the esti¬ 
mate of the long-range social effects 


and the apparent immediate value of 
the products for the market are so 
divergent. 

A number of techniques are avail¬ 
able for study of the economic and 
social impacts of weather modifica¬ 
tion. These include benefit-cost analy¬ 
sis, activity analysis, input-output 
analysis, and analysis of decision 
making, as well as numerical simula¬ 
tion studies. Despite differences of 
opinion as to research strategy, the 
various techniques tend to be comple¬ 
mentary. Much has been learned about 
methods from the social appraisal of 
engineering projects to modify the 
water cycle in river channels. 

One general approach is to define 
an actual or assumed modification of 
the weather and then attempt to an¬ 
alyze the full consequences of this to 
society. It is practical, for example, to 
estimate an increase in precipitation 
over a drainage area serving a hydro¬ 
electric plant and then follow the pos¬ 
sible impacts through the operation of 
the plant, the operation of downstream 
water projects, the production of 
other plants connected in the same 
system, and the productivity of the 
entire network. Along with the cost 
of cloud seeding, an attempt can be 
made to measure the full social bene- 


21 



fits and costs from the increased rain¬ 
fall, but these are hard to identify. 

Another approach is to analyze a 
sector of society so as to determine 
the particular points in the life of 
man where he is sensitive to changes 
in weather, and the degree to which 
a modification might lead to readjust¬ 
ment in amount or location of his 
activity. For example, it is obvious 
that the whole pattern of recreation 
in an area can shift very quickly 
because it happens to rain or snow at 
a given time and place, and that if 
the probability of precipitation were 
to be changed, the character of the 
regional recreation industry would 
alter. 

A basic difficulty in social research 
associated with weather modification 
is the difficulty of assessing the way 
in which man responds to a known 
weather circumstance. Just because 
there is a drought it does not auto¬ 
matically follow that a farmer in that 
area will move to another locality or 
adopt a different cropping schedule, 
even though analysis indicates it 
would be most profitable to do so. He 
may decide to stay, or to hold to his 
old farming methods. Understanding 
how people manage natural resources 
is essential to sound prediction of 


how they will react if the atmosphere 
is modified. 

Any adequate evaluation of social 
effects examines and compares the 
whole range of alternatives to weather 
and climate modification. An accurate 
weather forecast, for example, may 
be more valuable than an increase in 
rainfall, in some situations. If long- 
range forecasts were made reliable a 
farmer could change his cropping pat¬ 
tern for that year rather than support 
weather modification. As a further il¬ 
lustration, unless practical triggering 
mechanisms can be found, increasing 
the ability to forecast tornadoes and 
hurricanes is more rewarding than at¬ 
tempting to modify them. Adequate 
warning in many cases can allow man 
to adapt his activities at lower cost. 

There are other alternatives in ad¬ 
dition to forecasting: agronomic and 
genetic research can render farming 
less susceptible to the vagaries of 
weather. Engineering can protect 
transport from weather interruptions. 
A change in farm or industrial organi¬ 
zation can reduce its vulnerability to 
weather extremes. 

The need is great to assess more 
fully the social implications of weather 
and climate modification resulting 
from man’s discharging material into 


22 



the atmosphere. As more is known 
about the weather man could decide 
to build cities on spoil areas rather 
than on good farm land and in topo¬ 
graphic areas which help avoid pollu¬ 
tion of the environment. One alterna¬ 
tive here, of course, is to modify the 
weather over urban areas deliberately 
to offset the results of man’s inad¬ 
vertent weather changes. 

To the uncertainty as to what 
weather and climate modification man 
can accomplish must be added his 
lack of knowledge of the full conse¬ 
quences. New research programs 
should be based on the recognition 
that expanding the scientific knowl¬ 
edge of these consequences would be 
important to man even if no further 
gains were to be made in the technol¬ 
ogy of weather modification. The same 
understanding which would permit as¬ 
sessing the effects of weather and 
climate alteration would assist in 
working out other kinds of adjust¬ 
ments to weather phenomena. 

As indicated by the lack of social 
research about weather modification 
since the 1957 report of the Advisory 
Committee on Weather Control, when 
uncertainty concerning the feasibility 
of extensive weather modification is 
large the social implications tend to 


remain unexplored until a major prob¬ 
lem erupts. The Commission feels 
strongly this should not be the course 
of events in the future. All agencies 
engaged in weather modification at¬ 
tempts should give systematic atten¬ 
tion to the social implications. It is 
essential that funds be allocated for 
corollary research in the social sci¬ 
ences as related to weather and cli¬ 
mate modification, both deliberate and 
inadvertent. This research should em¬ 
brace the measurement of impacts, 
the identification of basic geographic 
relationships between human activity 
and weather and climate, and the con¬ 
ditions under which decisions about 
weather are made. 

THE LAW 

The ramifications to society—and 
hence to our legal system—of the 
technological capability to order 
weather would be enormous. Even a 
limited capacity to modify weather 
poses legal problems of great com¬ 
plexity. Urgent as these problems may 
soon become, uncertainty as to the 
scientific capability makes the recom¬ 
mendation of long-range legal solu¬ 
tions impossible at the present time. 


23 



Nevertheless, the law is already in¬ 
volved with weather modification and 
it is necessary to come to grips now 
with some aspects of the problems. 

The involvement of the law with 
weather modification is of two kinds: 

(1) the rules governing the responsi¬ 
bilities and liabilities of weather mod¬ 
ifiers to other members of the public; 

(2) regulation by government. As to 
the former, it is premature to make 
any recommendations concerning the 
rules of law which should be adopted 
to govern “property rights in weather,’* 
or the liabilities of weather modifiers 
with respect to those claiming injury 
to their persons or property. It is to 
be hoped that problems of weather 
modification will be decided on their 
own merits rather than on the basis 
of too facile analogies to the law re¬ 
specting land, water, wild animals, 
airspace, and the like. The few court 
decisions to date, while useful in il¬ 
lustrating the kinds of conflicts which 
can be expected to arise, do not give 
much basis for predicting how the 
law will develop. As the law stands, 
however, government contractors and 
grantees are subject to a risk that 
liability will be imposed on them for 
damage caused by their activities and 
that risk may have an inhibiting effect 


on participation in government pro¬ 
grams. 

As to regulation, some twenty-two 
states have enacted laws regulating 
weather modification. Most of these 
statutes require licenses. One state 
prohibits weather modification activ¬ 
ities entirely. While these statutes 
have had little effect on weather mod¬ 
ification activities, there is a distinct 
possibility that they may interfere 
with desirable Federal programs in 
the future. 

Until recently the only Federal 
“regulation” was the requirement by 
the National Science Foundation for 
reports on activities already under¬ 
taken by operators of whose activities 
the Foundation was aware. Effective 
January 1, 1966, the Foundation sub¬ 
stantially increased its record-keeping 
requirements and imposed on all op¬ 
erators a requirement of advance no¬ 
tice to it of any activity. 

The present authority of the Foun¬ 
dation under Public Law 85-510 pro¬ 
vides for obtaining—by regulation or 
otherwise—information, including ad¬ 
vance notice of any proposed weather 
modification activities, deemed neces¬ 
sary to its program of study, research, 
and evaluation. This information is an 
aid to the Federal research and devel- 


24 



opment effort and to the protection of 
its integrity. But, the lack of Federal 
authority to stop activities which may 
interfere with or contaminate Fed¬ 
erally-supported programs renders the 
Federal government powerless to pro¬ 
tect its programs from the actions of 
privately supported parties or state 
and local instrumentalities except by 
voluntary arrangements. 

Thus, the Commission recommends 
that the Federal government, by ap¬ 
propriate legislation, be empowered 
to: 

a) delay or halt all activities—pub¬ 
lic or private—in actual or potential 
conflict with weather and climate 
modification programs of the Federal 
Government, whether these programs 
are conducted for the Federal govern¬ 
ment, by its own agencies or by its 
grantees or contractors; 

b) immunize Federal agents, gran¬ 
tees, and contractors engaged in 
weather and climate modification ac¬ 
tivities from state and local govern¬ 
ment interference; and 

c) provide to Federal grantees and 
contractors indemnification or other 


protection against liability to the pub¬ 
lic for damages caused by Federal pro¬ 
grams of weather and climate modifi¬ 
cation. 

These recommendations are delib¬ 
erately restricted in scope, in the be¬ 
lief that in the developmental stage of 
weather and climate modification the 
minimum regulation consistent with 
immediate goals is desirable. How¬ 
ever, it should be recognized that as 
knowledge develops and as weather 
and climate modification activities in¬ 
crease, more comprehensive regula¬ 
tion in the public interest may be 
required. Such regulation might in¬ 
clude setting standards of profes¬ 
sional qualifications and financial 
responsibility for operators, establish¬ 
ment of appropriate authority for de¬ 
termining which experiments or oper¬ 
ations may be undertaken in the public 
interest, and a requirement of evalua¬ 
tion of activities by the operator. 

Finally, since weather no more re¬ 
spects national boundaries than it does 
State lines, it is hoped that early ef¬ 
forts will be made to delineate and 
study the international legal problems 
of weather and climate modification. 


25 



NEEDS AND OPPORTUNITIES 
FDR INTERNATIONAL COOPERATION 

The program of research required 
to develop the capability to modify 
weather and climate suggest a strong 
emphasis upon international coopera¬ 
tion. The extensive and significant 
work that is being done in other coun¬ 
tries underscores the need for pro¬ 
moting the international exchange of 
data and research findings for the pur¬ 
pose of maximizing their usefulness. 
The need for international collabora¬ 
tion in the actual planning and con¬ 
duct of research activities may be 
expected to increase as research moves 
out of the laboratory and into the 
realm of field experiments associated 
with the study of the dynamics of 
climate, the establishment of a global 
weather observation network and the 
investigation of other aspects of the 
general atmospheric circulation. The 
technological and human resources re¬ 
quired for the conduct of this type 
of research are far beyond the capabil¬ 
ity of most countries to provide indi¬ 
vidually. 

Looking into the future to the time 
when field experiments with weather 


or climate modification are expanded 
in scope and number and involve ac¬ 
tual attempts to introduce changes in 
the atmosphere, some form of interna¬ 
tional collaboration will be essential 
in the planning and execution of proj¬ 
ects that may have an effect not only 
upon the immediate localities but on 
areas in other countries and even 
upon other continents distant from 
the scene of work. It is possible that 
situations of this sort may arise in 
the near future if an expanded pro¬ 
gram of field experiments in cloud 
seeding is undertaken in areas near 
the northern or southern borders of 
the United States. An expansion in ex¬ 
perimentation with tropical hurri¬ 
canes may also present international 
complications. 

In the present stage of world affairs 
any scientific advance contributing 
significantly to man’s ability to affect 
the natural environment inevitably 
has a bearing upon the political rela¬ 
tions among nations and the quest for 
peace and security. The importance to 
military operations of a capability for 
modifying weather conditions is obvi¬ 
ous. It must be recognized that there 
is a remote possibility that sometime 
in the future a nation might develop 
the capability to use weather modifi- 


26 



cation to inflict damage on the econ¬ 
omy and civil population of another 
country. 

It is essential to develop the politi¬ 
cal and social controls over the use 
of this power which will maximize the 
opportunities for its constructive and 
peaceful use and minimize the factors 
which tend to involve it in the ten¬ 
sions and conflicts inherent in human 
society. The challenge and the oppor¬ 
tunity which are presented to the 
world community by the prospect of 
man’s achieving a power to modify 
his atmospheric environment is one of 
the most exciting long-range aspects 
of the subject. 

Thought must be given to the types 
of international organizations that will 
be needed, and the functions they 
should perform, if and when major 
operations in weather and climate 
modification affecting large continen¬ 
tal areas become feasible. Whether 
the assignment of operational respon¬ 
sibility to an international agency 
should be considered for the future 
deserves thought even at this early 
date. Consideration might be given to 
new concepts of international organi¬ 
zation and to the new problems of a 
technical or political nature that 
might be precipitated. 


The very fact that the development 
of a capability for influencing the at¬ 
mospheric environment is still in its 
infancy should widen the opportunity 
presented by this scientific endeavor 
to develop attitudes and patterns of 
collaboration which can contribute 
not only to the achievement of the 
practical, technological goals, but also 
to the relaxation of international ten¬ 
sions. 

Rarely has a more ample and in¬ 
viting opportunity been offered for 
advance thinking and planning re¬ 
garding the impact of a technological 
development upon international rela¬ 
tions. Progress in the diminution of 
international tensions and the achieve¬ 
ment of peace will come not so much 
from the dramatic resolution of basic 
international controversies as from 
the far less spectacular widening of 
areas of mutual interest among rival 
nations and from the growth in ways 
of cooperation. The field of weather 
and climate modification can serve 
well in this regard, in addition to 
realizing benefits of a more limited 
practical nature. 

The Commission believes that: 

1. It would be highly desirable for 
the Government of the United States, 


27 



in connection with the expansion of 
its program of weather and climate 
modification, to issue a basic state¬ 
ment of its views on the relationship 
of this national effort to the interests, 
hopes, and possible apprehensions of 
the rest of the world. Early enuncia¬ 
tion of national policy embodying two 
main points are recommended: 

a. that it is the purpose of the 
United States, with normal and due 
regard to its own basic interests, to 
pursue its efforts in weather and cli¬ 
mate modification for peaceful ends 
and for the constructive improvement 
of conditions of human life through¬ 
out the world; and 

b. that the United States, recog¬ 
nizing the interests and concerns of 
other countries, welcomes and solicits 
their cooperation, directly and through 
international arrangements, for the 
mutual achievement of human well¬ 
being. 

This cooperation should cover both 
research and, ultimately, operational 
programs of interest to other coun¬ 
tries. It should be concerned not only 
with deliberate, but also inadvertent 
human interventions in the atmos¬ 
phere that affect weather and climate. 
Such a policy declaration could be 
issued by the President or appropri¬ 


ately incorporated in any basic legis¬ 
lation on the subject of weather modi¬ 
fication which the Congress may enact. 

2. Steps should be taken by the 
United States, in concert with other 
nations, to explore the international 
institutional mechanisms that may be 
appropriate to foster international co¬ 
operation and cope with the problems 
which may be anticipated in the field 
of weather and climate modification. 
The United Nations and its special¬ 
ized agencies (e.g., the World Meteor¬ 
ological Organization) is suggested as 
a possible intergovernmental frame¬ 
work. The International Council of 
Scientific Unions and its associated 
unions (e.g., the International Union 
of Geodesy and Geophysics) could be 
a suitable non-governmental frame¬ 
work for these mechanisms. 

3. A major limitation affecting both 
advanced and developing countries is 
the shortage of trained personnel in 
atmospheric sciences at all levels. At¬ 
tention should be given to the ques¬ 
tion of how greater emphasis can be 
given to atmospheric sciences in ex¬ 
isting bilateral and multilateral pro¬ 
grams of education and technical 
cooperation; and to what additional 
measures may be needed to fill this 
deficiency. 


28 



4. Encouragement should be given 
to research on the impact of weather 
modification measures in foreign 
countries. The need has been previ¬ 
ously discussed for greater attention 
to the biological, economic and social 
aspects of weather modification in the 
United States. A different set of prob¬ 
lems may well be encountered in many 
of the developing countries where the 
natural environment and patterns of 
economic and social life present con¬ 
trasts to those prevailing in this coun¬ 
try. A greater understanding of the 
significance of these differences must 
precede any attempt to evaluate the 
suitability of various weather and cli¬ 
mate modification practices for spe¬ 
cific foreign areas and to design ap¬ 
propriate programs of cooperation. 

FISCAL AID ORGANIZATIONAL 
CONSIDERATIONS 

scops sod Nature ol me 
Naoonal Program 

The four principal elements of a 
national program for weather and cli¬ 
mate modification that appear to be 


warranted by the evidence presently 
at hand are as follows: 

1. There should be a strengthened 
program of fundamental research in 
the atmospheric sciences and the ini¬ 
tiation of complementary research in 
the biological and social sciences. Re¬ 
search in the atmospheric and the 
biological sciences should range from 
studies of a large and extensive nature 
involving many individuals and sub¬ 
stantial logistical support to the work 
of individual investigators. Desirable 
research on socio-economic aspects 
and the legal and international impli¬ 
cations will generally consist of stud¬ 
ies of relatively modest cost. 

2. There should be a concerted ef¬ 
fort directed specifically at the devel¬ 
opment of what may be called the 
technology of weather and climate 
modification. This is a sector in which 
a conspicuous gap is becoming evi¬ 
dent. The objectives should be early 
development and testing of techniques 
by which deliberate intervention in 
atmospheric processes can be accom¬ 
plished and consideration of the 
likely consequences of human activity 
in inadvertent intervention. Large- 
scale undertakings with substantial 
logistical support will be required and 
close liaison will be desirable with 


29 


the social, biological and other related 
studies. 

3. There should be provision for 
operational application by both the 
public and the private sectors as the 
feasibility and efficacy of modifica¬ 
tion techniques are validated. 

4. There should be such regulation 
as may be required to protect the 
public interest and advance the state 
of the art. Admittedly, it is difficult to 
arrive at a judgment on such matters 
as the timing and necessary scope of 
regulation and the form of administra¬ 
tion. In the opinion of the Commis¬ 
sion, however, it is not too soon to 
deal with this matter providing flexi¬ 
bility for adaptation to changing needs. 

Funding 

In the light of the above program, 
the following considerations with re¬ 
spect to funding appear to be revelant. 

1. Federal financial support for re¬ 
search and development activities in 
weather and climate modification 
needs to be increased substantially 
above present levels. 

2. Large field observational pro¬ 
grams and experiments of both a basic 
and an applied nature will be costly. 


They will require logistical support of 
substantial proportions in the form, 
for example, of suitable instrumenta¬ 
tion, aircraft, synchronous satellites 
and ecological laboratories. Some idea 
of the costs for which provision 
should be made is given by the esti¬ 
mate that a field experiment on hail 
by use of doppler radar and aircraft 
would cost at least $2 million a year. 

3. The weather and climate modifi¬ 
cation program needs a strong cen¬ 
tralized group as could be provided by 
a national laboratory. Such a group 
or center could serve as a focal point 
for research and development to con¬ 
duct and assist in large scale experi¬ 
ments and to provide logistic capabil¬ 
ities. The availability of a center with 
its facilities would serve as a nucleus 
for program planning and interchange 
of scientists on an international basis. 
It should be interdisciplinary in char¬ 
acter and provide for the conduct and 
support of research in those physical, 
biological and social sciences which 
are involved in weather and climate 
modification. 

4. Federal outlays for weather and 
climate modification research and de¬ 
velopment in Fiscal Year 1966 ap¬ 
proximate $7.2 million, exclusive of 
logistical support provided by the 


30 



Department of Defense. This sum con¬ 
stitutes about two percent of the ex¬ 
penditures of all Federal agencies for 
the atmospheric sciences and meteor¬ 
ological services. The potential im¬ 
portance of weather and climate 
modification, its propects for the 
future even in the face of remaining 
uncertainties in the present state of 
the art, and the magnitude of the ef¬ 
fort that may be required to resolve 
these uncertainties, require substan¬ 
tial funding. The Commission believes 
that by 1970 annual funding should be 
increased to the neighborhood of $20 
to $30 million, including logistics sup¬ 
port, or about five percent of the total 
for atmospheric sciences and meteor¬ 
ological services. In addition, increases 
of the same order will be needed for 
underlying basic research, including 
funds for items such as large com¬ 
puting facilities. Thus a total increase 
of $40 to $50 million per year may 
be envisaged by 1970. The level of 
funding must, of course, be constantly 
reviewed as progress is made. 



Weather and climate modification 
pervades many facets of human ac¬ 


tivity; it is natural that several Federal 
agencies have been involved as they 
fulfill agency missions. In the last full 
fiscal year, 1965, the Departments of 
Agriculture, Commerce, Defense and 
Interior and the National Science 
Foundation all expended funds for 
weather modification. No single 
agency in the Federal government now 
has responsibility for developing the 
technology of weather and climate 
modification. The need for such desig¬ 
nation is now, however, becoming 
evident. 

The future requirements of the 
agencies, and the needs of the weather 
and climate modification field, suggest 
that the organization of a national 
program should be unified around one 
agency, yet open for the participation 
of those agencies whose missions re¬ 
quire the conduct or support of 
weather and climate modification ac¬ 
tivities. The national program needs 
to provide for agencies such as the 
Federal Aviation Agency, which might 
operate over an area as small as an 
airport, to the State Department with 
its concern over the relationship of 
weather and climate modification to 
foreign policy. Thus, a national pro¬ 
gram should provide for the diversity 
of intellectual interests associated 


31 



with the subject, field and laboratory 
projects both large and small, and a 
growth in financial support consistent 
with prospective results. 

The Commission takes the 
position that: 

1. The mission of developing and 
testing techniques for modifying 
weather and climate should be as¬ 
signed to an agency in the Executive 
Branch of the Federal Government— 
for example, to the Environmental 
Science Services Administration of 
the Department of Commerce or to a 
completely new agency organized for 
the purpose. The mission should in¬ 
clude support and conduct of research 
and development and such operational 
activities as are needed for the fur¬ 
therance of the technology of weather 
and climate modification. This agency 
should have major but not exclusive 
responsibility, in collaboration with 
the State Department, for formulat¬ 
ing and implementing programs of 
weather and climate modification in¬ 
volving international cooperation. 

2. The National Science Foundation 
should continue and expand its sup¬ 
port of research in the atmospheric 
sciences, including its program di¬ 


rected at providing a satisfactory sci¬ 
entific basis for weather and climate 
modification. This should be carried 
on primarily at universities and col¬ 
leges and should include maintenance 
of the National Center for Atmos¬ 
pheric Research as a facility for the 
conduct of basic research on a scale 
beyond that feasible for individual 
university investigators. The degree 
of continuing and special attention 
given by the Foundation to the sup¬ 
port of the physical sciences, engi¬ 
neering, the biological sciences and 
the social sciences aspects of weather 
and climate modification should be 
reviewed from time to time in the 
light of the progress of the over-all 
national program. 

3. Federal agencies should under¬ 
take such operational activities as 
may be required for the effective dis¬ 
charge of their missions (e.g., sup¬ 
pression of lightning by the Forest 
Service, fog dispersion by the Federal 
Aviation Agency and rainfall augmen¬ 
tation for the reservoir system of the 
Department of the Interior). Also, 
pursuant to Executive Order 10521, 
Federal agencies should be free to 
conduct and support such research 
and development as may be required 
in the discharge of their missions. 


32 



(4) Insofar as the nature of a regu¬ 
latory agency is concerned, care must 
be taken to ensure access of all agen¬ 
cies to the information generated, 
while at the same time keeping regu¬ 
lation organizationally separated from 
research and development. For ex¬ 
ample, were the assignment of regula¬ 
tory responsibility to be made to the 
Secretary of Commerce, provision 
should be made that it be exercised 
outside those parts of the Department 
engaged in the conduct of research and 
development relating to weather and 
climate modification. Whether the reg¬ 
ulatory function needs to be divorced 
completely from the operating agen¬ 
cies, or can be assigned to a separate 
branch of such an agency, will depend 
largely on the extent of activity and 
the degree of regulation required. 

As to the jurisdiction of a regula¬ 
tory agency over other Federal agen¬ 
cies, insofar as regulation involves 
requirements of notice, reports, licens¬ 
ing of activities, etc., there seem to be 
good reasons why all agencies should 
be subject thereto. In addition, the 
regulatory agency should be given 
power to resolve minor conflicts be¬ 
tween agencies, such as the timing of 
particular experiments. 


It must be recognized that because 
the social effects will be complex and 
because Federal agencies are associ¬ 
ated with diverse interest groups there 
are likely to be major conflicts in pro¬ 
grams. Such conflicts go beyond the 
scope of regulation and involve admin¬ 
istrative coordination at the highest 
level. Their resolution should not be 
left to a regulatory agency. The Com¬ 
mission recommends that the Office 
of Science and Technology should 
consider establishment of a special 
mechanism for the coordination of 
weather modification policies and pro¬ 
grams. Such an entity could not only 
serve to resolve conflicts but could 
serve to promote unity in policy and 
deployment of funds and manpower 
with optimum effectiveness. 

5. Both the Executive Branch and 
the Congress may wish to have avail¬ 
able scientific and public policy advice 
from a group of knowledgeable people 
from outside the Government. This 
need might well be met by the appoint¬ 
ment of a standing committee in the 
National Academy of Sciences in co¬ 
operation with the National Academy 
of Engineering. The group should in¬ 
clude persons with experience in the 
physical, biological and social sciences 
and engineering. 


33 



mum 

For a review of the present status 
and potential of weather and climate 
modification, the Commission has de¬ 
pended mainly on the report of the 
Panel on Weather and Climate Modi¬ 
fication of the National Academy of 
Sciences*, the annual reports of the 
National Science Foundation, and the 
report of Gilman, et al.** Since the 
scientific basis has been discussed 
thoroughly in these reports, there is 
no need to repeat it here. Instead of a 
detailed discussion, an attempt is made 
here to delineate the problem in its 
broadest conceptual framework in 
order to describe the probable charac¬ 
ter of a well balanced plan for future 
action. 

Consideration of the physical prob¬ 
lems involved properly begins with a 
brief review of the atmosphere as a 
physical system, the dimensions of the 
quantities of energy that would be 
required to alter atmospheric processes 
by the exercise of brute force, and the 
nature of the instabilities that might 
be exploited to exert meaningful influ¬ 
ence within the limits of our ability 
to manipulate energy. These problems 
are discussed in Section II of this 


chapter. A brief summary of some of 
the most important conclusions of the 
NAS Panel is included in Section III. 
Also included in this chapter are brief 
discussions in Section IV of some of 
the projects on weather modification 
research carried out under the Na¬ 
tional Science Foundation program. 
In Section V there is a review of 
activities in foreign countries. Finally 
in Section VI a discussion is given in 
broad terms of prospects for future 
research. 

THE NATURE OF THE 
SCIENTIFIC PROBLEM 

The atmospheric envelope rotates 
with the earth, but does not rest 
quietly upon it. Air motion relative to 
the earth is induced by a non-uniform 
distribution of energy sources and 
sinks which are strongly influenced by 
those motions which they produce. 

* Weather and Climate Modification- 
Problems and Prospects, Vols. I and II, Na¬ 
tional Academy of Sciences-National Re¬ 
search Council, 1966 (NAS-NRC 1350). 

** Weather and Climate Modification, A 
Report to the Chief, United States Weather 
Bureau, July, 1965. (Both these reports in¬ 
clude extensive bibliographies.) 


n 06 KSS 

in 

nnsrecis 

IMUIIEI 
MD CLIMATE 
HMHUH0N 


34 


The motions themselves range in size 
over a spectrum that extends from the 
scale of planetary wave systems down 
to molecular movement. The sources 
and sinks of energy are variable in 
number and strength and exist mainly 
in response to the disposition of short¬ 
wave solar radiation, the flux of out¬ 
going long-wave radiation, the latent 
heat involved in the phase change of 
water and on the flow of sensible heat 
between the lower atmosphere and the 
underlying ocean or land. The kinetic 
energy of air motion is continuously 
exchanged with other forms of energy 
in the atmosphere and the kinetic 
energy of the several scales of atmos¬ 
pheric is continuously being trans¬ 
ferred from one scale to another. 

For the purpose at hand, the atmos¬ 
phere may be viewed as a complex 
physical system in which ascertain¬ 
able changes in air motion take place 
in response to identifiable forces. In 
principle, by altering these forces, con¬ 
sequent changes in the air motion can 
be influenced. Thus, in principle, con¬ 
trolling the weather or modifying 
the climate is scientifically possible. 
Whether or not it is practically realiz¬ 
able depends on a demonstration of 
the capability to alter these forces in 
a manner which will produce predict¬ 


able consequences. To be intellectu¬ 
ally satisfying, the cause and effect 
relationship would have to be under¬ 
stood in precise and exact detail. To 
be meaningful in a practical sense, it is 
only necessary to establish beyond a 
reasonable doubt that the cause and 
effect are related. 

It is useful to consider the order 
of magnitude of the kinetic energy 
involved in several scales of atmos¬ 
pheric subsystems. Some idea may be 
obtained from the following table: 


Atmospheric 

Approximate* 

Subsystems 

Energy in ergs 

Tornado funnel 

10 21 

Small thunderstorm 

10 22 

Large thunderstorm 

10 28 

Hurricane 

10 26 

Extratropical cyclone 

10 26 

General Circulation in the 

Northern Hemisphere 5xl0 27 


* Data for the tornado funnel and thunder¬ 
storms refer to a total lifetime of kinetic 
energy. Data for the other phenomena refer 
to kinetic energy at any given moment during 
maturity—which may be considerably less 
than the lifetime expenditure. 


An appreciation of the energy require¬ 
ments necessary were the kinetic 
energy of these atmospheric subsys¬ 
tems to be changed by 10 percent can 
be obtained from the next table. The 
column on the right lists the time 


35 



demand on the total electrical energy 
generating system of the United States 
if that source were to be drawn upon 
to change the kinetic energy of the 
atmospheric subsystem by ten percent. 

Atmospheric Approximate* 

Subsystem Time 

Tornado 30 seconds 

Small thunderstorm 5 minutes 
Large thunderstorm several hours 
Hurricane several days 

Extratropical cyclone 5-6 weeks 
General circulation in the 

Northern Hemisphere 6 years 

* Data for the tornado funnel and thunder¬ 
storms refer to a total lifetime of kinetic 
energy. Data for the other phenomena refer 
to kinetic energy at any given moment during 
maturity—which may be considerably less 
than the lifetime expenditure. 

One concludes that it is not immedi¬ 
ately practicable to think of altering 
these atmospheric subsystems to this 
extent by a direct application of 
energy. Nor is it reasonable to think 
of using energy directly to alter rain¬ 
fall. For example, the additional latent 
heat released by an increase of 10 per¬ 
cent in a rainfall totaling one inch 
over an area one hundred miles on a 
side would be the equivalent of about 
six days of the daily output of the 
electrical generating capacity of the 
United States. On the other hand, as 


will be seen presently, there exists 
some evidence that increases in rain¬ 
fall of this order may be obtained by 
seeding. A triggering mechanism based 
on an atmospheric instability is in¬ 
volved. It is appropriate, then, to con¬ 
sider the question of possible insta¬ 
bilities in the atmosphere. 

From simple observations of the life 
cycle of cumulus clouds, thunder¬ 
storms, tornadoes, hurricanes, and 
extratropical cyclones, it is evident 
that—within certain limits—the atmos¬ 
phere is unstable, that is, the ampli¬ 
tude of disturbance increases with 
time over a period of time which 
varies with the size of the disturbance. 
Moreover, significant energy transfor¬ 
mations are involved in the amplitude 
growth associated with these releases 
of energy initially in unstable form. 
At least four kinds of instability have 
been identified as potentially suscepti¬ 
ble to man’s efforts to trigger natural 
reactions. They are: 

1. The phase instability of water 
in the vapor phase in a condi¬ 
tion of supersaturation and in 
the liquid phase in the condi¬ 
tion of supercooling which, 
when released, provides a local 
source of sensible heat. 


36 



2. The colloidal instability of 
cloud particles which when 
released by precipitation, com¬ 
pletes the cycle by which latent 
heat is exchanged between the 
underlying surface and the 
atmosphere. 

3. The convective instability of 
the atmosphere which, when 
released, redistributes sensible 
energy in the vertical and often 
produces high local concentra¬ 
tions of kinetic and electrical 
energy. 

4. The baroclinic instability of 
the large scale circulation 
which, when released, redis¬ 
tribute sensible and kinetic 
energy in the horizontal plane, 
i.e., from pole to equator. 

The results of preliminary experi¬ 
mentation with the first three instabili¬ 
ties identified above lend support to 
the point of view that they may be the 
“Achilles’ Heel” in the atmospheric 
system by which large effects might be 
produced by relatively modest, but 
highly selective, interventions. The 
difficulties of treating quantitatively 
the non-linear processes inherent in 
instabilities are sobering. Some offset 


is provided, however, by the indica¬ 
tions that energy can progress upward 
through the several scales of exchange. 
It is pointed out in Volume II of the 
NAS Panel report that: 

The release of phase insta¬ 
bility in an aggregation of super¬ 
cooled cloud drops can simul¬ 
taneously colloidally destabilize 
the cloud into precipitation 
(through the Bergeron-Findei- 
sen mechanism) and, through 
the introduction of latent heat 
of fusion, convectively desta¬ 
bilize the volume of air within 
which the phase change is oc¬ 
curring. All of this has been 
observed, on a very small scale, 
in the seeding of stratocumulus 
clouds. It is not hard to imagine 
that induced convection or 
induced snowfall on a much 
larger scale could sufficiently 
alter the horizontal temperature 
distribution to trigger or subdue 
baroclinic instability, changing 
the natural development of 
large cyclonic storms. This, in 
turn, might alter the global radi¬ 
ation balance and thus influ¬ 
ence a fifth scale of instability 


37 



about which we can only con¬ 
jecture: the possible instability 
of global climate. 

The great variability of an¬ 
cient climates is accepted as 
fact, yet the cause of climatic 
change is far from being a set¬ 
tled issue. It is obvious that the 
earth-atmosphere system can 
support radically different cli¬ 
matic regimes, some of which 
could be disastrous to civiliza¬ 
tion. We do not yet know what 
can cause a shift from one 
climatic regime to another, 
whether change can occur in an 
“instant” of geologic time or 
only as a secular, cyclic proc¬ 
ess; our few theories still hang 
on the most tenuous of evi¬ 
dence. 

This, in barest outline, is the nature 
of the problem and some of its impli¬ 
cations. It is appropriate now to turn 
to some advances in recent years that 
suggest the present moment to be a 
propitious one to accelerate and 
strengthen the systematic exploration 
of the question. 


PRESENT STATUS OF 
WEATHER MODIFICATION 

The reports cited in the Introduction 
to this chapter give excellent discus¬ 
sions of the present status and prom¬ 
ise of weather and climate modifica¬ 
tion. 

A brief summary of some of the 
more important findings is given here. 
Some aspects of weather and climate 
modification are ready for practical 
applications, others are sufficiently 
promising to warrant programs of 
mission-oriented or applied research, 
still others are more remote possibili¬ 
ties for which no more than basic re¬ 
search can be justified at the present 
time. Furthest advanced is the prob¬ 
lem of dissipation of supercooled fog 
and stratus clouds by seeding, which 
has reached the stage of engineering 
applications for clearing of fog at air¬ 
ports. Experiments done here and 
abroad on cloud seeding for local in¬ 
crease of precipitation and for sup¬ 
pression of hail and of lightning, while 
far from conclusive, have shown some 
promise of success. Vigorous pro¬ 
grams of applied research should be 
pursued in these areas to delineate the 



potential and to optimize the proce¬ 
dures used. 

Without many more years of basic 
research on large-scale circulations of 
the atmosphere and the causes of cli¬ 
matic change, no program of modifica¬ 
tion of climate extending over large 
areas of the earth’s surface could or 
should be undertaken. Such a research 
program, although difficult and expen¬ 
sive, can be justified for aid in long- 
range forecasting and for making pos¬ 
sible predictions of consequences of 
inadvertent changes in the atmos¬ 
phere caused by activities of man. The 
possibility that such a program will in 
the future suggest methods for bene¬ 
ficial modification of climate is added 
incentive for undertaking it. 

Given below is a brief summary of 
some of the main conclusions of the 
reports on the present status of 
weather modification. A review is then 
given of some of the research pro¬ 
grams on weather modification under¬ 
taken during the past few years both 
here and abroad. The summary is nec¬ 
essarily quite brief; the reader is re¬ 
ferred to the reports cited for detailed 
information and background. 


Clearing ol supercooled 
stratus and Fag 

Effects of seeding by dry ice and by 
silver iodide were first demonstrated 
upon supercooled stratiform clouds. 
Recently attempts have been made to 
develop operational methods for clear¬ 
ing of supercooled fog at airports. 
Such methods have been used here 
and abroad for the past several years, 
particularly in the USSR, where the 
problem is more severe. Clearing of 
warm fog is much more difficult and 
no really satisfactory methods have 
been proposed. 

increase ni Local rreciiiiadon 
iv ending 

It has long been controversial as to 
whether local precipitation can be 
enhanced by seeding. The NAS Panel 
has made a statistical study of com¬ 
mercial seeding operations mostly 
using ground-based silver iodide gen¬ 
erators. Included were operations in 
the Eastern U.S. and in orographic 
situations in the Western U.S. In addi¬ 
tion, preliminary results of several 


39 



randomized experiments on seeding 
both in this country and abroad have 
become available during the past year 
and are included in the study. In Vol¬ 
ume I of the NAS Panel report it is 
stated: “There is increasing but still 
somewhat ambiguous statistical evi¬ 
dence that precipitation from some 
types of cloud and storm systems can 
be modestly increased or redistrib¬ 
uted by seeding techniques. The im¬ 
plications are manifold and of imme¬ 
diate national concern.” The statement 
cannot be made more conclusive be¬ 
cause of the possibility of some un¬ 
known source of bias or systematic 
error in the commercial seeding oper¬ 
ations and because chance fluctuations 
cannot be completely ruled out as an 
explanation of the more limited ran¬ 
domized tests. It should be empha¬ 
sized that the problem is an extremely 
complex one; there is great variability 
in cloud types and in ways in which 
precipitation can occur. The theoreti¬ 
cal knowledge of how seeding nuclei 
are introduced into clouds from 
ground-based generators and how pre¬ 
cipitation may be affected thereby is 
still quite rudimentary. 

Present indications, if taken at face 
value, are that local precipitation can 
be increased in many situations in the 


order of 10% by seeding. These posi¬ 
tive results are obtained in cases 
where rain would have fallen anyway 
without seeding; there is no evidence 
that seeding can induce rain to fall 
when normally there would be none. 
Thus, seeding is of limited value in 
relieving drought situations. 

There is very tenuous evidence that 
there may be under certain circum¬ 
stances a “rain shadow” effect, an 
area of decreased precipitation down¬ 
wind from the area of enhancement. 
There is no reason to suspect that this 
might be caused by “rain out” of avail¬ 
able moisture, since normally only a 
fraction is released as rain in any case. 
Theoretically, one could have consid¬ 
erable enhancement of local rainfall 
without appreciable influence on pre¬ 
cipitation further downwind. 

increase of rrecipitaaim 
by Forced conocnoo 

Suggestions have been made that pre¬ 
cipitation in some local areas could 
be increased by changes in the earth's 
surface to promote great absorption 
of heat and also greater transfer of 
heat and water vapor to the atmos- 


40 



phere. This would stimulate convec¬ 
tion; hopefully in sufficient amount to 
increase cloudiness and precipitation 
downwind. While some plans have 
been formulated, no field tests have 
been made to test this proposal. An¬ 
other method, which has given some 
indications of success in limited trials, 
makes use of seeding. It has been sug¬ 
gested that latent heat released by in¬ 
creased condensation of moisture into 
water droplets causes uplift and cloud 
formation. It may be that some of the 
observed increases in precipitation by 
cloud seeding result from enhanced 
convection rather than directly by 
nucleation of droplets. 

Lightning Suppression 

Studies carried out under Project Sky- 
fire of the U. S. Forest Service for the 
past several years have given indica¬ 
tions that seeding can alter cloud to 
ground lightning from thunderclouds. 
Background has been developed for a 
more thorough statistical study to see 
under what conditions seeding may 
be effective in reducing lightning and 
lightning-caused forest fires. Another 
suggestion, not yet tested on a large 
scale, is to introduce chaff (metallized 


strips) into clouds to decrease electric 
field gradients. 

Hail suppression 

Studies of suppression of hail by seed¬ 
ing or other techniques have mostly 
been carried out abroad and with in¬ 
conclusive results. There are reports 
that Soviet scientists by introducing 
seeding nuclei at the optimum posi¬ 
tion and time by use of antiaircraft 
shells have had success, but this work 
has not been duplicated in this coun¬ 
try. Volume I of the NAS Panel report 
states that “the U. S. hail research 
program is piecemeal and clearly of 
sub-critical size.” Plans are underway 
by the National Science Foundation 
to initiate a program in this area. 

Moderating Sonora Storms, 
Tornadoes, and Hurricanes 

Under Project Stormfury, several at¬ 
tempts have been made to modify 
hurricanes by seeding. The intent is 
to produce warming in the outer zone 
of the eye wall by releasing latent 
heat of fusion and so alter the pres- 


41 



sure and wind distributions. Results 
are so far inconclusive. Progress in 
these areas, where tremendous ener¬ 
gies are involved, will require much 
further basic research involving ex¬ 
tensive field investigations and devel¬ 
opment of theoretical models. 

Moulting me Microclimate 

MM 

The problems are largely concerned 
with means for preventing frost, for 
suppressing evaporation and for re¬ 
ducing effects of wind. Practical meth¬ 
ods have been in use for long periods 
of time; there has been limited appli¬ 
cation of modern knowledge of micro- 
meteorology to optimize procedures. 
Further research on boundary-layer 
energy and moisture exchange is highly 
desirable. 

Large-Scale Modification 
M Climate 

The possibilities of making use of in¬ 
stabilities in the atmosphere to alter 
the climate of large regions of the 


earth’s surface will be discussed in 
more detail later in this chapter. 

Modiflcaiioiis ol Climate 

For the future welfare of mankind it 
is important to be able to understand 
the factors involved in climatic change 
and thus to be able to predict inad¬ 
vertent changes in weather and cli¬ 
mate produced by present and future 
activities of man. Some beginnings in 
this direction are included in the NAS 
Panel report. One is an attempt to 
assess consequences of the increasing 
carbon dioxide content of the atmos¬ 
phere caused by the burning of fossil 
fuels. It is estimated that the CO 2 con¬ 
centration in the atmosphere has in¬ 
creased 10 to 15% in this century, 
making significant changes in the heat 
balance. The report states that “the 
implications of this upon tropospheric 
stability cannot be ignored” and that 
there is need for continuous monitor¬ 
ing of CO 2 content and of simulation 
of CO 2 effects “using the most sophis¬ 
ticated atmospheric models and nu¬ 
merical computers available” to assess 
the consequences. Another important 
problem is to determine effects of 
urbanization both on local climate and 


42 



possible indirect effects which may 
extend over much larger areas. Thus 
far there has been but little research 
on this problem. Effects produced by 
altering the rural landscape (agricul¬ 
ture, deforestation, etc.) appear to be 
less serious. Other problems consid¬ 
ered in the NAS Panel report are pos¬ 
sible effects of increase in water vapor 
content of the stratosphere by super¬ 
sonic transport aircraft and of con¬ 
tamination of the higher atmosphere 
by rocket exhaust. The report con¬ 
cludes that at present these are not 
serious problems. With increasing 
technology and population growth, 
problems associated with inadvertent 
changes in environment will become 
even more important in the future. 

JUXOMPUSHMEHTS OF THE 
NATIONAL SCIENCE FOUNDATION 
PROGRAM 

In order to put the problems of 
weather modification in perspective 
and to see what has been accom¬ 
plished in the intervening years, it is 
of interest to compare our present 
knowledge with that which existed in 
1957 at the time of the final report of 
the Advisory Committee on Weather 


Control. It should be recognized, how¬ 
ever, that the 1957 report is concerned 
primarily with effects of cloud seed¬ 
ing while we are now considering 
weather and climate modification from 
a much broader point of view, includ¬ 
ing inadvertent effects of man-made 
activities as well as deliberate at¬ 
tempts to modify the weather. 

Relying mainly on analysis of re¬ 
sults of commercial seeding opera¬ 
tions, the Advisory Committee on 
Weather Control reached the follow¬ 
ing conclusions: 

( 1) The statistical procedures em¬ 
ployed indicated that the seeding of 
winter-type storm clouds in moun¬ 
tainous areas in western United 
States produced an average increase 
in precipitation of 10 to 15 per cent 
from seeded storms with heavy 
odds that this increase was not the 
result of natural variations in the 
amount of rainfall. 

(2) In nonmountainous areas , the 
same statistical procedures did not 
detect any increase in precipitation 
that could be attributed to cloud 
seeding. This does not mean that 
effects may not have been produced. 
The greater variability of rainfall 
patterns in nonmountainous areas 
made the techniques less sensitive 


43 



for picking up small changes which 
might have occurred there than 
when applied to the mountainous 
regions. 

(3) No evidence was found in the 
evaluation of any project which was 
intended to increase precipitation 
that cloud seeding had produced a 
detectable negative effect on pre¬ 
cipitation. 

(4) Available hail frequency data 
were completely inadequate for 
evaluation purposes and no conclu¬ 
sions as to the effectiveness of hail 
suppression projects could be 
reached. 

Conclusion (1) was later severely 
criticized as being based on inade¬ 
quate statistical evidence and lack of 
adequate controls, but present indica¬ 
tions are that it is probably correct. 
Evidence presented in the NAS Panel 
report suggests that seeding in some 
cases may enhance local precipitation 
even in nonmountainous areas by 
similar amounts. There is some rather 
tenuous evidence of a shadow zone of 
decreased precipitation beyond the 
area of local enhancement. Thus con¬ 
clusions (2) and (3) no longer appear 
to be valid. A current statement con¬ 
cerning the status of hail suppression 


could not be made much more definite 
then conclusion (4). 

The Advisory Committee on 
Weather Control report recommended 
an increase in research in meteorology 
and related fields; that the National 
Science Foundation be the agency 
designated to promote and support 
such research and to be “a central 
point for the assembly, evaluation, and 
dissemination of information and that 
the development in large numbers of 
highly qualified research scientists in 
the field is essential. The report also 
emphasized basic research leading to 
a scientific understanding of weather, 
with the aim in part of putting cloud 
seeding on a firmer scientific basis. In 
1957 there were few professional peo¬ 
ple working on scientific aspects of 
weather modification. As a result of 
subsequent activities and support of 
the Foundation and other agencies, 
there are now involved a number of 
outstanding groups in universities, 
government, and industry. Among the 
universities that have groups engaged 
in research related to cloud physics 
and weather modification are Arizona, 
Chicago, Colorado State, New Mexico 
Institute of Mining, Nevada, New 
York University, Pennsylvania State, 
State University of New York, and the 


44 



University of Washington. The Pro¬ 
gram of the Illinois State Water Sur¬ 
vey is partially supported by the 
State. An outline of the programs of 
various government agencies is given 
in this report in the chapter on Fund¬ 
ing and Administration Requirements. 
Several industrial organizations such 
as A. D. Little, Inc. have research pro¬ 
grams on various aspects of weather 
modification. There are of the order of 
40 to 50 concerns engaged in com¬ 
mercial seeding operations. 

While a great deal has been learned 
about the physics of clouds and the 
precipitation process, because of the 
extreme complexity of the problem 
there is still far from a scientific un¬ 
derstanding of effects of cloud seed¬ 
ing and the dynamics of clouds. A 
brief review of a few of the major 
projects sponsored in whole or in part 
by the Foundation may be in order: 

(1] One of the most important is 
the University of Chicago “Project 
Whitetop” which has demonstrated 
the importance of the warm rain 
coalescence process in many super¬ 
cooled convective cloud systems 
which formerly were thought to de¬ 
pend entirely on the Bergeron-Fin- 
deisen ice process. A preliminary anal¬ 
ysis of a cloud seeding program ex¬ 


tending over a five year period at 
West Plains, Missouri, indicates a re¬ 
gion of increased radar precipitation 
echo extending 30-50 miles downwind 
of the seeding line followed by a 
broad region further downwind with 
decreased precipitation. This precipi¬ 
tation pattern was detected by radar 
echoes and supported in part by rain 
gauge data. These data suggest that 
seeding may produce a growth of 
clouds along the seeding line which 
sets up a stationary wave-like pertur¬ 
bation extending downstream. In the 
region 40-80 miles downstream the 
air is sinking rather than rising and so 
is unfavorable for cloud growth. Thus, 
the shadow zone of decreased precipi¬ 
tation may result indirectly from a 
dynamical effect rather than from 
prior rainout of available moisture. 

(2) For the past ten years, the Kings 
River Conservation District has sup¬ 
ported a cloud seeding program by 
Atmospherics, Inc. in the Kings River 
Drainage area on the Western slopes 
of the Sierra Nevada Range in Cali¬ 
fornia. A grant from the Foundation 
provided for additional measurements 
for study of cloud physics and precip¬ 
itation. Recent analysis of the data 
indicates an average 6.1% increase in 
runoff in the drainage area due to 


45 



seeding for the period. This supports 
preliminary results of a research 
study by Colorado State University in 
the area of Climax, Colorado, and of 
other commercial seeding operations, 
extending over shorter periods of 
time, that seeding can give a moderate 
increase in precipitation in orographic 
situations. An analysis of these and 
other seeding experiments is included 
in the NAS Panel report. 

(3) Project Stormfury, a joint 
Weather Bureau-Navy project, with 
support from the Foundation, is an 
attempt to modify tropical clouds and 
perhaps hurricanes by massive seed¬ 
ing. The idea here is to enhance cloud 
buoyancy and thus later cloud dynam¬ 
ics by release of latent heat of fusion. 
Conclusive results have not yet been 
obtained, although there is consider¬ 
able evidence that clouds can be mod¬ 
ified in this way. Howell, in 1960, pre¬ 
sented data on effects of seeding of 
tropical cumuli which indicated en¬ 
hanced buoyancy and a consequent 
increase of precipitation. A group at 
Pennsylvania State University has 
been investigating the possibility of 
providing positive buoyancy to clouds 
in the lee wave of mountain systems 
by seeding. 


(4) A great deal has been learned 
from laboratory studies about the nu- 
cleation process with Agl as well as 
with other materials; however, much 
remains to be done in correlating 
such laboratory work with effects 
produced by various practical seeding 
methods. 

(5) Considerable progress has been 
made in studies of clearing of super¬ 
cooled stratus and fog by seeding. The 
problem of dissipation of supercooled 
fog over airports is now largely one of 
design of suitable seeding devices. It 
has been suggested that because of 
their stability and consequent repro¬ 
ducibility of results, supercooled stra¬ 
tus clouds could be used for testing of 
seeding agents. 

(6) Studies are being made of elec¬ 
tric fields in clouds, their possible in¬ 
fluence on the precipitation mechan¬ 
ism and of methods for changing the 
electric field patterns as a possible 
technique for modification of clouds. 

Much of the activity since 1957, and 
particularly that under Foundation 
sponsorship has been aimed at basic 
scientific understanding. In complex 
problems this is a sound if often slow, 
way of arriving at practical goals. 
With a sufficiently thorough under- 


46 



standing one should be able to esti¬ 
mate both the possibilities and limita¬ 
tions of various techniques. At the 
other extreme are the purely empirical 
methods of trying various procedures 
and observing the overall results with¬ 
out worrying too much about the de¬ 
tailed mechanisms of how and why 
they occur. In cases where there is a 
great deal of natural variability, one 
must rely on sound statistical meth¬ 
ods with adequate controls. Unfortu¬ 
nately many of the empirical studies 
of the past for one reason or another 
did not yield conclusive results. The 
empirical and basic approaches are 
both valuable and complement one 
another. Empirical discoveries may 
stimulate basic research and lead to 
new understanding. Scientific under¬ 
standing, even though far from com¬ 
plete, may suggest new or modified 
empirical approaches. 

The problems involved in statistical 
design of experiments are discussed 
in this report in the chapter on Sta¬ 
tistical Aspects of Weather Modifica¬ 
tion. 

ACTIVITIES III FOREIGN COUNTRIES 

The achievement in artificial nucle- 
ation by Schaefer, Langmuir and Von- 


negut in 1946-47 had repercussions 
throughout the world. Within a few 
years weather modification activities 
had been initiated in a number of 
countries. In its Third Annual Report 
on Weather Modification for FY 1961 
the National Science Foundation gave 
data on work underway in sixteen 
countries. 1 More than 100 research 
stations outside of the United States 
were reported as being engaged in 
weather modification work. As in the 
United States, a major emphasis in 
most foreign countries has been placed 
upon cloud seeding or other efforts at 
rainmaking. Considerable attention in 
some countries has been given to fog 
dissipation and hail suppression, 
while significant basic scientific re¬ 
search programs have been undertaken 
in several lands. 

Australia, faced with growing de¬ 
mands for water, both for agriculture 
and hydroelectric power, has under¬ 
taken significant programs of basic re¬ 
search in cloud physics as well as 
large scale field experiments in cloud 
seeding. A variety of cloud-seeding 
experiments has been carried out in 
Canada by both government and pri¬ 
vate agencies since 1948. France has 
established a broad program of scien¬ 
tific research coupled with practical 


47 



experiments. Ten different organiza¬ 
tions are engaged in French weather 
modification programs; in addition to 
fundamental research, special interest 
has been displayed in hail prevention 
and fog dispersal. Laboratory research 
has been featured in Germany, where 
weather modification activities were 
late in getting underway. Interest in 
Great Britain has also been directed 
almost exclusively at basic research 
in cloud physics, cloud dynamics and 
atmospheric electricity. 

A special concern with the practi¬ 
cal problem of hail suppression has 
characterized the weather modifica¬ 
tion work in Switzerland. The Federal 
Commission for Studying Hail Forma¬ 
tion and Hail Prevention, established 
in 1950, operates three laboratories 
which have contributed significant 
knowledge to the understanding of 
hail formation and have carried out a 
variety of experiments in cloud seed¬ 
ing as a means of prevention. Similar 
concern with urgent national prob¬ 
lems has been noted in the develop¬ 
ment of weather modification work in 
Israel, where water supplies are of 
paramount importance to the econ¬ 
omy; a broad program of research and 
field experimentation has been di¬ 
rected at the investigation of the nat¬ 


ural processes of rain formation and 
their possible manipulation by artifi¬ 
cial means. An active program of both 
basic research and empirical studies 
of cloud seeding has been pursued in 
Japan. Some success has been re¬ 
ported in seeding programs. In 1964 
an International Conference on Cloud 
Physics was held in Japan. 

Of particular importance in the 
work going on in foreign countries is 
that being carried forward in the So¬ 
viet Union. Faced with a number of 
serious problems created by a hostile 
natural environment affecting the eco¬ 
nomic welfare of the country, the So¬ 
viet Union has shown an active and 
intensive interest in the subjects of 
weather and climate modification. The 
delegation of the U. S. Weather Bu¬ 
reau which visited the Soviet Union 
in May, 1964, returning a similar visit 
to the United States by Soviet scien¬ 
tists earlier that year, was particularly 
impressed by the broad scope of the 
Soviet program and the large re¬ 
sources of manpower and funds that 
were being concentrated on weather 
modification and related activities. Al¬ 
though actual work is undertaken in 
a number of institutes located in vari¬ 
ous parts of the Soviet Union, and 
includes activities in both the Arctic 


48 



and Antarctic, the Soviet activities ap¬ 
pear to be well integrated into a na¬ 
tional program and guided towards the 
achievement of objectives directly re¬ 
lated to the economic and social needs 
of the country. 

Among the Soviet Union’s theoreti¬ 
cal studies, emphasis has been placed 
upon research in cloud physics at 
numerous centers, as well as upon 
theoretical evaluations of the possi¬ 
bilities of climate modification. Indic¬ 
ative of the broad dimensions and 
imaginative character of Soviet think¬ 
ing have been speculative suggestions 
of climate modification by erection of 
major hydraulic structures which 
would alter ocean currents, artificially 
inducing changes in snow cover, pro¬ 
ducing changes in cloud cover by 
seeding, and altering the surface to 
induce lifting or subsidence of air. 
One of the most spectacular is the 
suggestion of damming the Bearing 
Straits. 

Field experiments have concen¬ 
trated upon three areas of common 
concern to many other countries: dis¬ 
sipation of fog and low stratus clouds, 
particularly over airports; suppres¬ 
sion of hail; and rainmaking. While 
statistical tests have generally not 
been undertaken, many Soviet scien¬ 


tists are convinced the empirical evi¬ 
dence is sufficient to support their 
claims of success. Such claims include 
statements that the dissipation of su¬ 
percooled fog and low stratus over 
airports has now become operational; 
that cloud seeding can increase pre¬ 
cipitation from frontal clouds by 
around ten per cent; and that the pos¬ 
sibility has been demonstrated of 
greatly decreasing the formation of 
large, damaging hail. Considerable 
benefit has apparently been derived 
by Soviet scientists from work done 
in the United States and other coun¬ 
tries as a result of the thorough and 
extensive program of review and 
translation of scientific literature—an 
aspect of research some American sci¬ 
entists believe could well be expanded 
in this country. 

The resume given above of some of 
the major weather modification activ¬ 
ities in foreign countries is by no 
means a complete inventory. Other 
work is being initiated and carried 
forward in several other countries. 
The wide distribution of activity in 
this field throughout the world is in 
one sense a reflection of the essen¬ 
tially international character of sci¬ 
ence. It is also an indication of the 
growing realization by scientists, and 


49 


by governments, that the possibility 
of weather and climate modification 
may have profound repercussions 
upon the future economic and social 
welfare of their countries. 

PERSPECTIVES FOR RESEARCH 

It is recognized that several inter¬ 
related branches of earth science must 
be developed as a foundation for the 
technology of environmental control. 
These include study of the mechan¬ 
isms and energy balances involved in 
the hydrologic cycle, development of 
further understanding of the dynamics 
of climate through atmospheric mod¬ 
eling and computational experiments 
including weather prediction, broad¬ 
ening both field and laboratory re¬ 
search in cloud physics and dynamics, 
and a thorough examination of the 
non-atmospheric mechanisms, such as 
modification of the surface character¬ 
istics of the land and sea, which might 
conceivably alter weather or climate. 
Each of these will be discussed in 
turn. 


Hydrologic cycle 

The words Weather Modification 
have come, through usage, to mean 
the conscious intervention by man in 
the precipitation process; either its 
augmentation or reduction and ulti¬ 
mately its control. In this view atten¬ 
tion is centered on the atmosphere. 
But weather is only a link in the 
hydrologic cycle in which water, 
through various energy exchanges, is 
distilled from the oceans or transpired 
from the ground water table into the 
atmosphere, is stored in the atmos¬ 
phere for a time, and eventually re¬ 
turned to earth in another place. 

In principle, effective practice of 
weather and climate modification may 
consist of activities which produce 
alterations at any point in the hydro- 
logic cycle that could conceivably lead 
to control of persistent or momentary 
extremes. Since the global water cycle 
is a closed but multiply-connected 
loop (much like the cardiovascular 
system) the consequences or effective¬ 
ness of intervention may either be 
“healed” by self-regulatory processes 
which give the hydrological system 
its stability, or lead to systematic 
change. 


50 



The problem of weather and climate 
modification, then, requires sufficiently 
detailed understanding of the energy 
transformations of the hydrologic 
cycle to know where, how t when , and 
with what intensity man’s interven¬ 
tion in the natural system may pro¬ 
duce significant alterations. Effective 
pursuit of this understanding will re¬ 
quire the concerted knowledge and 
skills of geologists, hydrologists, 
oceanographers, meteorologists, engi¬ 
neers, and the close support of those 
versed in applied physics, mathe¬ 
matics, ecology, and chemistry. As 
yet this breadth of enterprise has 
neither been reached nor contem¬ 
plated. 

In the present state of knowledge 
atmospheric intervention seems to 
offer a promising point at which to 
exert an influence upon the hydro- 
logic cycle in the interests of man¬ 
kind. However, as knowledge is ad¬ 
vanced in other areas of the earth 
sciences, particularly in oceanogra¬ 
phy, it is possible that other and per¬ 
haps even more promising alternatives 
may come to light. 


Dimamics oi mm 

In the various aspects of the weather 
modification problem thought has been 
centered around the issues of water 
resources particularly in those areas 
where there is a shortage of supply. 
This is a natural concern because it 
is one ultimate goal of the weather 
and climate modification concept to 
regulate, if not increase, the availabil¬ 
ity of potable water for the uses of 
mankind. In consideration of this goal, 
it is necessary to think not of times 
and localities where the need for 
water is most sorely felt, but of the 
dynamics of climate over the whole 
earth in which the dry areas have 
context. 

Since precipitation in the free air is 
associated with the rise and adiabatic 
cooling of moist air, the processes to 
be encouraged must be those which 
will induce rising motion, especially 
of maritime air over regions presently 
deficient in rainfall. Rising air occurs 
in three principal situations: in cumu¬ 
lus convection (micro to macro scale), 
in orographic lifting (meso to macro 
scale) and in frontal lifting (macro 
scale). Once initiated, lifting may be 
encouraged by energy releases asso- 


51 



dated with phase changes in the water 
burden of the atmosphere. Lifting may 
also be encouraged by physical or 
thermal topographic influences on the 
earth’s surface. 

In regions where an excess of pre¬ 
cipitation exists it might also be de¬ 
sirable to suppress rising motions of 
air. The mechanisms governing sink¬ 
ing motions are not yet clear and must 
be understood before regional weather 
modification can be contemplated. 

Rising and sinking motions in the 
general circulation of the atmosphere 
tend to be arranged in zonal patterns, 
hence climates of the earth also tend 
to be developed in zones. The non- 
zonal irregularities in the arrangement 
of climatic belts on the earth are found 
in the transition regions between land 
and sea, because heating air flow is 
predominantly zonal while the distri¬ 
bution of land is more nearly merid¬ 
ional. 

In the atmosphere, as it is now con¬ 
stituted, there are belts of rising and 
sinking air the emerge with statistical 
significance. In the intertropical con¬ 
vergence near the geographic equator 
rising motions occur and cumulus con¬ 
vection is the principal mechanism 
for the release of precipitation. In the 
subtropical zones near 30° latitude, 


the desert belt in each hemisphere, 
sinking predominates and there is a 
consequent excess of evaporation over 
precipitation owing to the adiabatic 
heating of the descending air. In high 
middle latitudes frontal lifting is the 
predominant mechanism promoting 
the development of stratiform clouds 
from which precipitation may occur. 
Local anomalies in this general pat¬ 
tern are developed by orographic in¬ 
fluences and surface effects. Effective 
weather regulation would rearrange 
the geographic limits within which 
these statistically predominant zonal 
configurations of rainfall and evapora¬ 
tion now occur. 

A problem of this magnitude re¬ 
quires study of the susceptibility of 
the atmosphere to change by system¬ 
atic influences. It is already well known 
that the atmosphere responds as a 
whole to disturbances within any part 
of it. It is also known that the atmos¬ 
phere exhibits a kind of statistical 
stability. If it did not, the subject of 
climatology could not be pursued. One 
has, therefore, to learn through an in¬ 
tensive series of computer simulation 
experiments and quantitative labora¬ 
tory investigations with rotating mod¬ 
els where, how forcefully and how 
often the atmosphere must be dis- 


52 



turbed to change the statistics of cli¬ 
matology. The question at this point 
should be addressed to a study of 
changes of all kinds. Once the effects 
and energy requirements for interven¬ 
tion are known from laboratory and 
numerical studies, it would then be 
possible to select certain changes as 
a basis for field experimentation. It 
would also be known how massive 
such undertakings in the field might 
have to be to produce effects that 
emerge clearly above the normal levels 
of atmospheric variability. 

One would hope that model ex¬ 
periments will divulge the type of 
instabilities that can be seized upon 
to swing a climate regime in a 
particular direction. If it becomes 
evident that the atmosphere only 
marginally sustains a particular phe¬ 
nomenon; for example , if it appears 
that hurricanes are not an essential 
element of the general circulation , 
then perhaps one can accomplish 
the corresponding heat flux entirely 
by a related phenomenon which is 
more prevalent , i.e. weakly organ¬ 
ized convection . Speculating on a 
much larger time scale: is the oc¬ 
currence of an ice age or the forma¬ 
tion of a large desert an inexorable 
necessity or are they the conse¬ 


quence of weak but systematic 
interactions which may easily be 
disrupted once we learn what the 
critically participating processes 
are?* 

A program of this kind is bound to 
involve a considerable expansion of 
effort and facilities. For example, the 
computational effort required is 
roughly two orders of magnitude 
greater than that possible with the 
largest machine now in existence. The 
suitable equipment for laboratory re¬ 
search in rotating models might also 
cause an expansion of effort by a fac¬ 
tor of two or three over the present 
level. Still, the hope would be that 
this kind of undertaking could be 
accomplished with only moderately 
increased resources of manpower, 
through student training and the at¬ 
traction of foreign scientists into this 
sphere of activity. Since the atmos¬ 
pheric, oceanographic and geologic 
properties of the whole earth are to 
be considered, there would be a nat¬ 
ural basis for international coopera¬ 
tion. 


* Smagorinsky, J. 1964 statement at the 
National Science Foundation Interagency 
Conference on Weather Modification, Wash¬ 
ington, D. C., 5-6 November 1965. 


53 



Prediction 

Useful as control might be in 
weather management, prediction can 
serve an almost equally valuable social 
and economic function. Accurate pre¬ 
diction is possible only when there is 
virtually complete physical under¬ 
standing of the processes interacting 
to produce change. Prediction also 
requires a very complete description 
of initial conditions; which is to say 
it will soon be necessary to establish 
a global network of observatories 
across the land and sea areas of the 
whole earth to fill out the significance 
of satellite reports. Steps toward this 
end are already being taken in con¬ 
nection with the World Weather 
Watch, but consideration of the cor¬ 
responding networks needed to deter¬ 
mine the fluxes of heat, mass and 
momentum within the oceans and be¬ 
tween the oceans and atmosphere is 
not yet so far advanced. The related 
technological problems of sensing, 
telemetry and maintenance of field 
equipment in a global network have 
not even been defined. However, were 
surface and upper air observations to 
be available on a global basis the 
means for their analysis are even now 


becoming well established. And with 
their continued development, comput¬ 
ers may be expected to have reached 
the necessary levels of storage capac¬ 
ity and speed within a decade. Having 
this much so close at hand it would 
seem appropriate that the scientific 
and engineering aspects of a global ob¬ 
servation network be given immediate 
attention. 

Cloud Physics and Dynamos 

The problem of weather and climate 
modification is basically centered on 
finding procedures by which man may 
intervene with relatively low expendi¬ 
tures of power to achieve detectable 
alterations of the atmospheric regi¬ 
men, and of coupling that power to 
the atmosphere in efficient ways. In 
present cloud seeding practices a point 
or line source of material is diffused 
into a significantly large volume of air 
by atmospheric turbulence. The dis¬ 
turbance produced in the air feeds on 
the energy of phase changes in the 
water substance in the atmosphere, 
and with consequent conversions of 
latent to sensible heat, presumably 
alters the buoyancy of air parcels to 
excite or amplify vertical motion and 


54 



the further exchange of sensible and 
latent heat until the point of detect¬ 
able returns has been passed. 

Some recent experiments suggest 
that beyond the site where precipita¬ 
tion is excited by silver iodide nuclea- 
tion there is a “rain shadow” which 
in itself suggests that wave-like effects 
are involved. This finding may have 
revealed a useful principle. 

It is a relatively common observa¬ 
tion that there are many kinds of quasi- 
periodic wave motions in the atmos¬ 
phere. Cloud streets are often seen, 
lenticular clouds stand in trains in the 
lee of mountains, long cumulus trains 
develop downwind of ocean islands, 
cyclonic storms develop in families 
along fronts, and fronts themselves 
have conspicuously wave-like charac¬ 
teristics. 

As a beginning it would seem de¬ 
sirable that cloud seeding experiments 
be extended to include study of the 
plume of dynamical consequences 
downwind, with an eye to the possi¬ 
bility that resonances might be ex¬ 
cited if the phase of successive inter¬ 
ventions were correctly placed in 
space and time, and conversely that 
damping could be managed if the 
points of excitation were deliberately 
placed out of phase. In this way the 


effects of intervention might be ampli¬ 
fied enough to be detectable beyond 
the present screen of statistics, and at 
the same time, means developed to 
control the area of influence. 

In parallel with this thought, there 
is, as yet, very little understanding of 
the natural processes by which water 
vapor condenses to form cloud drop¬ 
lets, of how such droplets coalesce to 
form precipitable entities, or how the 
additions of seeding nuclei alter the 
natural process. We suggest that along 
with that necessary study it may be 
well to acknowledge that the earth 
supports a pronounced electric poten¬ 
tial gradient which is changed in cer¬ 
tain storm conditions. Since it is well 
known that the coalescence of spray¬ 
ing jets is markedly influenced by the 
presence of an electric field far weaker 
than many of these, it seems only rea¬ 
sonable to encourage deeper study of 
electrical relationships in the atmos¬ 
phere. Causality is not the question, 
but rather the interdependence or co¬ 
existence of electric fields and coales¬ 
cence phenomena that needs exami¬ 
nation, with the prospect that through 
deliberate atmospheric electrification 
some control of the coalescence proc¬ 
ess may be exercised. 


55 



The field of cloud physics and dy¬ 
namics must be developed far beyond 
its present state if weather and climate 
modification is to become a matter of 
practical concern. The questions of 
droplet formation and growth of pre- 
cipitable elements in the dynamics of 
clouds need examination on a broader 
base than the present level of effort 
or varieties of research can supply. 
Achievement of this state of under¬ 
standing will require the best efforts 
of those versed in surface physics and 
chemistry in addition to physical and 
dynamical meterology and possibly 
also in acoustics, electrostatics and 
dynamics, and high energy optics. As 
funding is increased for weather and 
climate modification early priorities of 
expenditure should be accorded the 
development of cloud physics and 
dynamics as a necessary basis for 
sound technology. 



The atmosphere is underlain by solid 
earth and broad expanses of sea water 
and responds to their influences. The 
effects on the atmosphere of season¬ 
ally differential heating and cooling 
of the solid earth and oceans produce 


monsoonal winds and rains on all sub¬ 
tropical continents, govern the curva¬ 
tures of the polar fronts and the 
courses of both tropical and extra- 
tropical cyclones. The oceans provide 
the atmosphere with most of its mois¬ 
ture, and because of their large thermal 
inertia tend to hold fast the maritime 
centers of high and low surface pres¬ 
sure, and thus fix the patterns of 
world climate. 

The natural scale of oceanic fea¬ 
tures is large indeed, but through 
liquid-filled rotating models many of 
their physical aspects can be studied 
in the laboratory and the effects of 
deliberate modifications assessed. For 
example, the consequences to the 
ocean circulation to be expected if the 
planetary wind field were to be al¬ 
tered or the effects of barriers placed 
across narrow gaps (such as the Ber¬ 
ing, Florida, or Gibraltar Straits) can 
be examined in rotating models. Simi¬ 
lar studies can be made for the land, 
such as the utter removal of all moun¬ 
tains from the earth or adding the 
topography of past continental gla¬ 
ciers, but perhaps better in these cases 
with numerical models. Both of these 
investigative techniques have been 
brought to useful levels of refinement 
in the past two decades. 


56 



Granting a present capability to 
make reasonable estimates of the 
physical consequences of large scale 
alterations of the land and sea, the 
difficult part of the question of non- 
atmospheric intervention in climate 
and weather is shifted to that of field 
methods, power requirements and con¬ 
trols; and of the sites for possibly de¬ 
sirable surface alterations. In this 
connection the ocean offers some 
especially interesting possibilities. 

It is now well established that the 
ocean is characteristically in a state 
of stable density stratification. While 
density increases with depth; in the 
tropics and subtropics the surface 
water tends to be warm and salt while 
the subsurface layers grow colder and 
somewhat fresher with depth. The 
transition zone between these two 
principal water types is the main 
thermocline which is found at a depth 
of about one-hundred meters in the 
tropics and some several hundred 
meters in middle latitudes. Thus to 
cool the surface of the ocean it is 
necessary only to bring the cold water 
below the main thermocline upward 
through the relatively short distance 
to the surface. 

This might be done with some effi¬ 
ciency by infusing the cold layers 


with a curtain of small bubbles. If the 
entrained water is lifted isothermally 
it will tend to sink again; but if the 
process is quasi-diabatic a mixture of 
cool, somewhat fresher water can be 
made to remain on the surface and 
to move off with the surface current. 

The effect on the atmosphere of 
such alterations of the surface tem¬ 
perature of even great torrents like 
the Gulf Stream or Kuroshio might be 
small at first because, though swift, 
these currents are very narrow. Still, 
in time, the wind-driven Ekman trans¬ 
port would carry the modified surface 
layer seaward and generalize the in¬ 
fluence of surface cooling. 

In Arctic waters bubble sheets have 
been proposed to keep navigable wa¬ 
ters clear of ice. But in low and mid¬ 
dle latitudes surface warming is more 
difficult to contrive. For the North 
Atlantic there is a possible procedure 
in the fenestration of the Panamanian 
Isthmus. 

These influences depend on the 
thermal stability of the oceans. But the 
salt burden of the ocean is unstably 
stratified. The warmth of the surface 
water permits the uppermost layers 
to be saltier than those at depth. In 
consequence a parcel of warm, salt 
surface water carried downward and 


57 



allowed to lose heat to its surround¬ 
ings, will continue to lose buoyancy 
and sink. Conversely, a parcel of cold, 
relatively fresh deep water once 
started upward, will continue to gain 
buoyancy and rise. Such parcels can¬ 
not be large, because of the heat 
transfer requirements, but there is 
nothing, in theory, to prevent them 
from being so numerous that their 
net affect on vertical mixing might be 
of geophysical significance. 

Finally it may be worth recalling 
that the surface of the ocean receives 
more than two-thirds of the world’s 
supply of precipitation and dew, and 
is the ultimate reservoir of not only 
river discharges but glacial melt water. 
All of this water is fresh but presently 
irrecoverable. Still more fresh water 
substance lies bound as ice. Ice is re¬ 
coverable. Should the need grow so 
desperate or economical means of 
transportation be devised, ice and its 
melt water provide an as yet unex¬ 
ploited resource. 

CONCLUSIONS UNO 
RECOMMENDATIONS 

The Commission concludes that 
sound progress toward the technology 


of weather and climate modification 
must be based on four fundamental 
pursuits: 

(a) assessment and development 
of an understanding of 
natural climatic change. 

(b) assesment of the extent and 
development of the under¬ 
standing of inadvertent modi¬ 
fications of weather and cli¬ 
mate. 

(c) improvement of the process 
of weather prediction as a 
social benefit and as proof of 
scientific understanding of at¬ 
mospheric behavior, and 

(d) development of means for 
deliberate intervention in at¬ 
mospheric processes for 
weather and climate control 
and evaluation of their con¬ 
sequences. 

As steps toward these attainments the 
Commission recommends that the fol¬ 
lowing enterprises be fostered: 

(1) Examination of the routes, rates 
and reservoirs of water sub¬ 
stance and energy exchanges in 
all aspects of the hydrologic 
cycle. 

(2] Investigation by numerical lab¬ 
oratory and field experiments of 


58 



the dynamics of climate as a 
basic study for weather modifi¬ 
cation technology. 

(3) Advancement of weather pre¬ 
diction as a proof of under¬ 
standing, including support of 
this effort by the establishment 
of a global weather observation 
network. 

(4) Broadening of the knowledge of 
cloud physics and dynamics in 
the laboratory and field, with at¬ 
tention to wave phenomena and 
an evaluation of electrical influ¬ 
ences. 


(5) Study of the effects of large 
scale surface modification by 
numerical and laboratory models 
of the oceanic and atmospheric 
general circulation, and of prac¬ 
tical means for surface modifica¬ 
tion of the land and sea. 

(6) Study of the radiative effects of 
changes in the atmospheric com¬ 
position and alteration of its 
transparency that urban growth 
and new forms of industry, 
transportation or land use may 
evoke. 


59 



INTRODUCTION 

Man is an organism directly de¬ 
pendent on other organisms for many 
of his materials. He also struggles 
with other organisms, most of them 
quite small, that prey upon him, eat 
his food, or otherwise challenge his 
existence. Anything that has a gen¬ 
eral and significant effect upon plants 
and animals, making some more abun¬ 
dant, others less so, is of primary con¬ 
cern to mankind, for it strikes at the 
very basis of human existence. 
Changes in weather and climate may 
be expected to have such effects. It 
follows that any program of weather 
modification must give serious atten¬ 
tion to adverse as well as beneficial 
biological aspects. 

As Lynton Caldwell observed in the 
Yale Review, “Biopolitics: Science, 
Ethics and Public Policy,” Vol. LIV: 
1-16, 1964, biologists are with increas¬ 
ing frequency finding themselves at 
variance with other segments of so¬ 
ciety on matters of public policy. Ex¬ 
amples range from questions concern¬ 
ing how much radioactive or pesti- 
cidal materials should be permitted 
loose in the environment to the rela¬ 
tive merits of trying to preserve from 


extinction a natural species popula¬ 
tion. Contrary to }. P. Miller’s whim- 
sey biologists cannot limit themselves 
to “proving that what must be done 
for political reasons is biologically 
safe for the human race.” 

MEANS OF PREDICTING 
CONSEOUENCES OF 
WEATHER MODIFICATION 

It must be recognized that the pres¬ 
ent state of knowledge places uncom¬ 
fortable limits on the prediction of the 
biological consequences of modifying 
the weather. Several lines of investi¬ 
gation can be used, however, to pro¬ 
vide information. 

The Study Committee of the Ecological 
Society of America was asked by the Na¬ 
tional Science Foundation to undertake a 
study of the present status of knowledge of 
effects of weather and climate on plants and 
animals and to recommend the type of bio¬ 
logical program that should be associated 
with research in weather modification. The 
study was made by an Ad Hoc Weather 
Working Group, chaired by Daniel A. Liv¬ 
ingstone, Duke University, and is reported 
in a paper entitled “Biological Aspects of 
Weather Modification,” to be published in 
the March, 1966 issue of the Bulletin of the 
Ecological Society of America. See the Ap¬ 
pendix. 


mouNicu. 
mis of 

MO 

1*11100 


60 



These will be discussed, indicating 
the special advantages and deficien¬ 
cies of each avenue of study. 

Lahoraiory Studies 

A single organism or a small number 
of the same species can be subjected 
to controlled experimental conditions 
in the laboratory, and the response 
to various elements of climate, such 
as temperature, moisture and light, 
systematically investigated. This 
basically straightforward approach is 
not without complications. If, for ex¬ 
ample, one seeks to investigate the 
effect of temperature upon the growth 
of a plant species, it is not sufficient 
to measure the plant’s growth at a 
variety of constant temperatures. 
Some plants are more influenced by 
the daytime temperature, some by the 
night temperature, while others thrive 
best under conditions that are speci¬ 
fied by the difference between day 
and night temperature. The responses 
to light are similarly complicated. For 
reasons such as these, the experimen¬ 
tal approach has been applied to a 
very small fraction of the known spe¬ 
cies of plants and animals, and there 
are only a handful, such as man, the 


speckled trout, the loblolly pine, and 
a number of crop plants, that have 
been investigated at all exhaustively. 

This laboratory approach has sev¬ 
eral deficiencies as a means for pre¬ 
dicting the field results of weather 
modification. The response to weather 
may be very different for organisms of 
the same species collected in different 
parts of its range. Because of genetic 
changes, an organism taken directly 
from the field and grown under con¬ 
trolled environmental conditions in 
the laboratory may react differently 
from one which is the result of sev¬ 
eral generations of genetic selection 
pressure in a large population growing 
under similar conditions. The most 
serious deficiency of this approach is 
that it treats species in isolation. In 
nature, very few organisms are lim¬ 
ited in range by direct climatic condi¬ 
tions that exceed their physiological 
limits, but rather by competition with 
other species that are better able to 
cope with the prevailing conditions. 
Such considerations limit the applic¬ 
ability of results obtained in the lab¬ 
oratory for predicting results of 
weather modification in the field. 



61 



Records Ol Annual variation 

The results of year-to-year varia¬ 
tions in the natural weather on biolog¬ 
ical phenomena can be used as a 
basis for predicting the results of sim¬ 
ilar perturbations produced by man. 
This method is suitable for predicting 
the effects of short-term weather mod¬ 
ifications that are similar in nature 
and extend to natural climatic fluctu¬ 
ations. With these limitations, it can 
be used to predict the offsets of 
weather modification upon a few 
well-studied crop plants of great eco¬ 
nomic importance, and a few well- 
studied insect or microscopic pests. 

Biogeographicai and 
raiBnecnlogltal Records 

Biogeography furnishes another use¬ 
ful source of information about the 
relation of organisms to climatic fac¬ 
tors. Correlations between the distri¬ 
bution of organisms and climatic 
conditions suggest that climate has a 
primary role in determining these dis¬ 
tributions. The predictions that can 
be made from biogeographicai data 


are safest when they are most general. 
A change from grassland to savanna 
under increased rainfall can be pre¬ 
dicted much more securely than the 
species composition of the savanna or 
the exact amount of rainfall increase 
that would be required to effect the 
change. 

Study of the fossil record has also 
provided a wealth of information 
about the biological effects of a par¬ 
ticular set of climatic changes, those 
ticular set of climatic changes, those 
associated with glacial and intergla¬ 
cial conditions, and a substantial body 
changes in the more remote proglacial 
periods. Use of these data is hampered 
by lack of independent information 
about the actual physical changes in 
climate that were involved, so that 
much investigation of these changes 
consists of an attempt to infer cli¬ 
matic changes from the biological evi¬ 
dence, rather than determining the 
way in which organisms have been in¬ 
fluenced by climate. Nevertheless, the 
fossil record gives the only available 
information about the biological re¬ 
sults of a major climatic change on a 
global scale, and for this reason it is 
particularly valuable. 


62 



Monitoring of selected 
communities 

Experimental plans for weather 
modification should insure a maxi¬ 
mum yield of biological data on the 
nature of effects. This requires both 
the establishment of comparable con¬ 
trol areas outside the areas of modifi¬ 
cation and pre-modification monitor¬ 
ing of sample areas in both the 
control and modified areas. Natural 
communities would be selected for 
study in an area in which weather is 
to be modified and permanent experi¬ 
mental plots established in them. Well 
before weather modification, the biota 
on these plots should be inventoried 
in detail and mapped or photographed. 
Such studies should precede modifica¬ 
tion by a long enough period to col¬ 
lect data on the normal fluctuations of 
the communities and populations. The 
plots would be re-studied during and 
after periods of weather modification 
to determine what species expanded 
their populations and what species 
lost ground; what species disappeared 
from the community and what new 
species entered. Since proper evalua¬ 
tions will require confidence limits for 


any statements concerning effects, the 
sample areas must be well replicated. 
Monitoring experiments will be diffi¬ 
cult to set up. It is patently impossible 
to study every species in a rigorous 
way, and it is quite possible that ran¬ 
domly selected species will turn out 
not to be those most useful for the 
study. Some guiding principles might 
include a mixture of the following 
attacks: 1. A well-replicated series of 
reasonably detailed examinations of 
selected natural biological arrays at 
transition areas joining biological 
communities which are apt to show 
changes with the predicted shifts. 2. 
Examination of a range of agricultural 
and other artificial ecosystems for 
changes in disease, pests, yields, har¬ 
vest dates, etc. 3. Studies of relative 
changes in population sizes, reproduc¬ 
tive success, etc., of a selection of 
more easily studied organisms within 
blocks of homogeneous natural com¬ 
munities away from transition areas. 
Reasonable controls are essential; 
hence, in order to be effective, moni¬ 
toring must be done outside these 
areas in comparable sites. 


63 



Computer simulation Studies 

Computer simulation studies pro¬ 
vide a method for predicting biolog¬ 
ical effects of weather modification. 
Two quite different approaches to 
computer studies are available. A 
model that approximates reality very 
closely cannot be made at present for 
any given area because of the lack of 
data. Hence, computer experimenta¬ 
tion may need to be postponed for 5 
to 10 years until the requisite data on 
the location in question are available. 
An alternative is to proceed immedi¬ 
ately to construction of a simulation 
model, using data on the same, or re¬ 
lated organisms from places other 
than the proposed site for the weather 
modification experiment. In so doing 
the following question must be asked: 
“How would an ecosystem similar to 
that which presently exists at the site 
for the weather modification experi¬ 
ment be altered if one modified typ¬ 
ical sequences of weather data within 
ranges of values known to be realis¬ 
tic?” In general, the type of thing to 
determine with simulation studies is 
whether certain combinations of strat¬ 
egies or strategies used singly, show 
certain broad features that are rela¬ 


tively invariant even when indepen¬ 
dent variables are run through a wide 
range of values on the computer. Also, 
it is desirable to see if certain strate¬ 
gies are grossly uneconomical if ap¬ 
plied under certain circumstances. 

The logic of the simulation ap¬ 
proach is bolstered by studies on such 
insect pests as the spruce bud worm. 
Through the longterm concerted ef¬ 
fort of large teams of investigators, it 
has been possible to construct models 
sufficiently close to reality to have 
practical use in predicting outbreaks 
and in choosing control strategies. 
Outbreaks of plant diseases are prob¬ 
ably also capable of being studied 
with the same methods. 

The principal motivation for com¬ 
puter simulation is cost. It is enor¬ 
mously cheaper to run experiments 
on the computer than to try out a 
great variety of weather modification 
experiments in nature and observe the 
results. Both the cost of the experi¬ 
ment and the losses due to the experi¬ 
ment by using simulation as a supple¬ 
ment to an actual experimental pro¬ 
gram are saved. The basic structure of 
the computer simulation program will 
be a set of functional relationships 
which mimic the dynamic properties 
of all relationships between and within 


64 



soils, plants, animals, site factors and 
weather, with respect to changes both 
in variables through time and in dis¬ 
persal of entities through space with 
the passage of time. 

PREDICTED DIOLODICJIL RESPONSES 
OF WEATHER MODIFICATION 

An ecological system consisting of 
agricultural fields is well enough un¬ 
derstood that effects of specified 
weather and climate modifications 
can be predicted with some assurance. 
In a more complex system consisting 
of many more species of interacting 
plants and animals, the complexity is 
so great that it is not possible to make 
detailed quantitative predictions. 
However, certain general effects can 
be outlined. In illustrating this, con¬ 
sider temperature changes up to sev¬ 
eral degrees Fahrenheit and rainfall 
changes, principally increases, of 
some tens of percent of the present 
annual average on reasonably well- 
watered lands. 


Denerai Effects 

Paleoecological studies in many of 
the climatic regions of the earth indi¬ 
cate that temperature modification 
corresponding to an annual average 
difference of 3° to 4°F. brings notice¬ 
able alterations in population levels of 
many resident plants and animals and 
the appearance and disappearance of 
some other species. In many cases, 
however, the broad kind of vegeta¬ 
tion, such as hardwood forest or 
grassland, still remains. A change in 
temperature of twice this magnitude 
brings replacement of many species 
by others, wide changes in population 
levels of species present at both ex¬ 
tremes, and in many cases replace¬ 
ment of one major kind of community 
by another. 

From long-term studies of the 
American prairie, it may be predicted 
that the direct effect of moderate 
changes in rainfall on the biological 
communities as a whole may be ex¬ 
pected to be relatively slight, mostly 
involving shifts in sites occupied by 
species. The changes will probably be 
slow unless large areas become defoli¬ 
ated or killed through the anticipated 
increase in certain pests or the com- 


65 



munity is otherwise seriously dis¬ 
turbed. However, changes in rainfall 
or temperature which are of sufficient 
magnitude to have general usefulness 
seem likely to be of sufficent magni¬ 
tude to produce substantial disturb¬ 
ances in natural communities. 

Most studies showing correlations 
between weather conditions and 
changes in the abundance of one or 
more species of organisms have also 
brought out the fact that it is the 
weather during a few critical months 
that is important, rather than the aver¬ 
age conditions over the years. Thus, 
for many species, a minor increase in 
the average annual precipitation could 
mean either enormous increases or 
great mortality, provided that the 
extra rain fell during a period that was 
critical for survival or reproductive 
success. 

increase in crop ProMM 

It seems quite clear that an increase 
in rainfall would result in an increase 
in production of cultivated crops over 
a large part of the earth. Even a reduc¬ 
tion in variance in rainfall, or the 
ability to control its seasonal distri¬ 
bution, would lead to an increase in 


productivity if all other conditions 
remained the same, because the in¬ 
creased reliability of the return would 
permit more efficient farming opera¬ 
tions. 

species Extinction end Disruption 
o( Natural coiamunffles 

With the growth of human popula¬ 
tion and its spread over the land in 
the United States, native species are 
increasingly confined to small sanctu¬ 
aries—parks, wildlife refuges, and 
mountain ranges. These are islands 
surrounded by oceans of land inten¬ 
sively occupied by man, and it is not 
generally possible for wild species to 
migrate across the rural and suburban 
oceans from one island to another, to 
survive climatic change. If climate is 
so changed that a species is no longer 
able to survive in a given natural area, 
that species cannot migrate but must 
become extinct there. Extinction of 
species implies reduction in species- 
diversity, the richness of natural com¬ 
munities in numbers of species. Re¬ 
duced species-diversity and shifts in 
population distributions resulting 
from weather and climate modifica- 


66 



tion would combine to reduce the sta¬ 
bility of natural communities. 

There are differences of opinion 
among biologists about the extent to 
which a particular modification would 
affect the stability of natural commu¬ 
nities. Most would expect an appre¬ 
ciable disturbance to result from a 
modification great enough to be useful 
economically. Some species would be¬ 
come more vulnerable to outbreaks 
of pests and some natural preserves 
would become less aesthetically at¬ 
tractive and less valuable for research 
purposes. The economic consequences 
would be felt in communities that are 
used for grazing or lumbering. 

It is likely that the changes pro¬ 
duced by weather and climate modi¬ 
fication in insular remnants of natural 
communities will be consistently un¬ 
favorable ones. Immigration of the 
normal respondent species is subject 
to interference. In more continuous 
areas the shifts would result in more 
temporary but not necessarily incon¬ 
sequential instability. 

Prohahie increase in crop Pests 

For insect pests, there exist numer¬ 
ous studies indicating relationships 


between abundance and weather con¬ 
ditions. The number of cases is suffi¬ 
ciently impressive to permit the con¬ 
clusion that changes in weather from 
year to year do lead to changes in the 
abundance of certain species, and in 
some instances lead to changes in 
their distributions. It seems probable 
that many, if not all, of these species 
will be highly destructive to agricul¬ 
tural enterprises or to the natural 
vegetation, or to both. Unfortunately, 
too little is known of the mechanisms 
of population control of most species 
for us to be able to predict which 
species will become serious pests 
under altered weather conditions. It is 
also true that some likely changes in 
weather would result in abnormally 
low populations of other species. Well 
known examples of species for which 
high rainfall is deleterious are the 
chinch bug, Blissus leucoptorus, and 
the pale western cutworm, Porosogro - 
tis orthogonia. It is likely, however, 
that weather modification will lead to 
large agricultural losses due to the 
increases induced in populations of 
some terrestrial pest species, and that 
these losses will not be compensated 
by perhaps equally frequent reduc¬ 
tions in the populations of other 
species. 


67 



Probable increase 
in Disease vectors 

One class of organisms, the ones 
that are borne by arthropod vectors 
and cause serious diseases in man and 
his domestic animals, are deserving of 
special attention. Although there is 
some reason to believe that other dis¬ 
eases may be influenced by weather 
conditions as well, it is clearly estab¬ 
lished that many of those with arthro¬ 
pod intermediate hosts are dependent 
upon weather conditions. One can pre¬ 
dict that weather modification would 
produce a shift in the pattern of vec¬ 
tor-borne diseases. In any plan to 
modify the weather, disease must be 
given very serious consideration, for 
it may be of greater economic impor¬ 
tance than the circumstances which 
stimulated interest in weather modi¬ 
fication. 

The outbreak of many insect pests 
seems to be triggered by a rather un¬ 
usual meteorological situation in one 
restricted part of the range. The popu¬ 
lation builds up first in that local cen¬ 
ter and spreads out in all directions in 
the form of a wave. This pattern is 
similar to that of many human dis¬ 


eases, some of them carried by arthro¬ 
pod vectors, such as bubonic plague. 
It is not believed that an epidemic of 
plague would necessarily result from 
weather modifications, but the possi¬ 
bility exists that there might be some 
sort of weather modification which 
would cause it to occur. There is a 
substantial reservoir of sylvatic plague 
in the United States. 

Many bacterial and fungal diseases 
of crops are also known to be highly 
responsive to weather. Increased rain¬ 
fall, more summer humidity, warmer 
or cooler temperatures would all have 
effects on plant pathogens. Not enough 
is known to predict the significance 
of the almost certain changes. 

Etleef ol Possible Rain-Shadows 

While an increase in precipitation 
has predictable results among which 
both favorable and unfavorable effects 
can be expected, and which might off¬ 
set each other to some extent, a con¬ 
comitant decrease in precipitation in 
another area has no beneficial effects 
to offset the obvious damage. 


68 


CONCLUSIONS UNO 
RECOMMENDATIONS OF THE 
ECOLOOICIIL SOCIETY 
W0RKIN6 OOOUP 

1. Living things are adapted to the 
weather that actually prevails, and 
any change in that weather will be 
generally deleterious to them. 

2. The largest credit item for 
weather modification is likely to be an 
increase in primary production of the 
drier parts of the land surface through 
improvements in rainfall. Even the 
ability to control seasonal distribution 
of rainfall would lead to more efficient 
farming operations. Realization of the 
potential increase in production would 
depend upon being able to modify the 
rainfall without major pest outbreaks 
and extinction and disruption of nat¬ 
ural communities. It is not certain that 
this would be possible. 

3. The largest weather modification 
debit item is likely to spring from the 
decreased stability of communities, 
which would manifest itself in an in¬ 
crease in pests, weeds, and pathogens. 
The identity of the species involved 


in these disruptions cannot be pre¬ 
dicted, nor can their cost. 

4. For the present, weather and 
climate modification should be re¬ 
stricted to local small-scale operations. 

5. Larger scale operations, such as 
an attempt to increase the rainfall of 
any substantial part of this country, 
should not be undertaken, from a bio¬ 
logical point of view, in the present 
state of knowledge. 

6. All weather modification experi¬ 
ments of a scale large enough to have 
important biological consequences, 
such as those currently envisioned for 
the Upper Colorado Basin, should be 
preceded and accompanied by careful 
ecological monitoring and computer 
simulation studies. Manipulating the 
weather to obtain a net benefit will 
demand much better understanding of 
the interactions of weather, climate 
and organisms than now available. 

7. Adequate understanding of the 
interrelationship of weather, climate 
and ecology will demand a very ex¬ 
pensive long-term research program. 
Present resources of ecologically- 
trained investigators are inadequate 
to cope with these problems. 

The Working Group of the Ecologi¬ 
cal Society of America, which pro- 


69 



vided background material for the 
Commission, was concerned primarily 
with modifications of weather sys¬ 
tems ranging from a single cloud to 
an extratropical cyclonic storm. The 
Working Group stated that short-term 
modifications of weather of a magni¬ 
tude similar to the fluctuations in 
nature are least likely to have danger¬ 
ous unforeseen consequences. If un¬ 
desirable results appear, the modifica¬ 
tions can be discontinued. Repeated 


operations on the scale mentioned are 
likely, however, to have far reaching 
biological consequences as pointed 
out in the previous sections, and some 
of the biological changes would not 
be reversible. This advisory group 
recommended that repeated and long 
term modifications of weather not be 
attempted without prior careful and 
well planned monitoring or computer 
simulation studies of the biological 
consequences of particular kinds of 
weather modification. 


70 



MUM. 

JUTECIS 

OF 

NEITIKI 

MUIHCUMN 


i* nisHT sitnim 

Problems of statistical methodology 
arise when there is a controversy as 
to interpretation of data already ac¬ 
cumulated or as to ways of going 
about acquiring additional informa¬ 
tion. That such controversy should 
arise in connection with weather 
modification experiments is hardly 
surprising. 

Almost twenty years after the orig¬ 
inal experiments in cloud seeding, 
conclusive evidence acceptable to the 
scientific community as to ground 
precipitation effects of cloud seeding 
is still lacking. The basic issue of the 
effectiveness of seeding non-oro- 
graphic cumulus clouds has been sub¬ 
ject to sharp changes of opinion and 
to conflicting evaluation in recent 
months. In the absence of conclusive 
guidance from scientific experimental 
data, the National Academy of Sci¬ 
ences Panel on Weather and Climate 
Modification embarked on an inten¬ 
sive statistical study of data from 
commercial projects. This analysis 
concluded with the impressively posi¬ 
tive findings on the efficacy of cloud 
seeding—a position supported in gen¬ 
eral by the available scientific data. 


This analysis, however, has not com¬ 
pletely dispelled the skepticism con¬ 
cerning evidence obtained as a by¬ 
product of operational activities. The 
question is not whether to use statis¬ 
tical but how to use it in the early 
design and subsequent analysis of 
experiments. 

THE CONFERENCES OH 
STATISTICAL METHODOLOGY 

The National Science Foundation 
sponsored three conferences for the 

This chapter draws upon materials as¬ 
sembled by Prof. Byron W. Brown, Jr. of 
the University of Minnesota as a result of 
three conferences held under the auspices 
of a National Science Foundation grant. 
These conferences brought together scien¬ 
tists actively engaged in weather modifica¬ 
tion research and statisticians experienced 
in the planning of scientific experiments. 
Also, acknowledgement is made to unpub¬ 
lished memoranda and letters by Dr. Julien 
Bigelow (Institute for Advanced Study), Pro¬ 
fessor William Kruskal (The University of 
Chicago), Dr. Theodore Harris (Rand Corpo¬ 
ration), Professor Jerzy Ney man and Dr. 
Elizabeth Scott (University of California, 
Berkeley), Mr. Glenn Brier and Dr. Joanne 
Simpson (USWB) and many other statisti¬ 
cians and scientists who participated in 
these conferences. The list of participants in 
these conferences appears as Footnote 1 to 
this chapter. 


71 



purpose of bringing together statisti¬ 
cians and scientists interested in the 
statistical aspects of weather modi¬ 
fication experiments. The first confer¬ 
ence, in January, 1965, brought to¬ 
gether scientists participating in many 
field experiments throughout the 
country. These scientists briefly re¬ 
viewed these programs and plans, 
with special reference to the statisti¬ 
cal problems that have been encoun¬ 
tered. The statisticians present had an 
opportunity to comment on these brief 
reviews and on their own experiences 
in this area. 

The second conference, in April, 
1965, focused on Project Stormfury. 
The project director and the statistical 
consultants for this project presented 
the results of past work, the criticism 
of this work, and the plans for the 
summer of 1965. The statisticians and 
weather modification scientists used 
this project as the point of departure 
for discussion of general questions of 
design and evaluation of experiments. 

At the third conference, in June, 
1965, scientists in the Bureau of Rec¬ 
lamation, and in projects sponsored 
by the Bureau, reported on a number 
of Bureau projects and related work. 
Again there was an opportunity for 
other scientists and statisticians at¬ 


tending the meeting to ask questions, 
comment on the presentations, and be 
questioned in turn. 

CONFERENCE FINDINGS 

A number of results have come 
from these conferences. 

1. Field experiments are a neces¬ 
sary part of a research program on 
w'eather modification by cloud seed¬ 
ing. Laboratory experiments of the 
scope and refinement necessary to 
predict field results are not economi¬ 
cally feasible and, further, the theory 
necessary for laboratory simulation of 
the mechanisms of free air precipita¬ 
tion has not been developed. Practical 
effects must be estimated in the field. 

2. The number of variables in¬ 
volved and the lack of knowledge 
about the details of atmospheric pro¬ 
cesses make weather modification 
field experiments difficult to plan and 
evaluate. Careful use of the best tech¬ 
niques in scientific methodology is re¬ 
quired. This entails the cooperation of 
scientists who can frame the hypoth¬ 
eses and specify some of the impor¬ 
tant variables, statisticians who can 
suggest ways of using this information 
to gain precision, mathematicians, in- 


72 



strumentation specialists, engineers, 
hydrologists and others. 

3. Many of the investigators in this 
field do not have formal training in 
statistical methodology. A few do not 
realize this methodology is essential 
to their work. Others realize the use¬ 
fulness of statistical methodology for 
planning and evaluation, but do not 
have adequate statistical support for 
their programs. 

4. Planing and evaluation of weath¬ 
er modification experiments present 
some special problems in statistical 
methodology. These problems must 
be resolved or circumvented if re¬ 
search in weather modification is to 
benefit from the use of statistical 
principles. Statistical research is 
needed in questions such as the fol¬ 
lowing: optimal spacing of rain gages, 
optimal use of rain gage data, effects 
of crystals contaminating unseeded 
areas, best ways of taking advantage 
of auto-correlations and cross-corre¬ 
lations in rain gage data. 

CONFERENCE RECOMMENDATIONS 

1. Statistical training should be 
given greater emphasis in the aca¬ 
demic program of scientists and engi¬ 


neers interested in the atmospheric 
sciences. This statistical training 
should include the principles of field 
experimentation—nature of statistical 
models, random allocation of treat¬ 
ments, local control, replication and 
blind evaluation—as well as the clas¬ 
sical techniques of design and data 
analysis. 

2. Steps should be taken to assure 
that government-supported research 
utilizes statistical principles in plan¬ 
ning and analysis. It is desirable that 
statisticians participate with meteor¬ 
ologists, and other scientists, in the 
evaluation of proposals for govern¬ 
ment-supported research. 

3. Statistical advice for scientists 
in this field should be made available 
through (i) sponsorship of conferences 
(e.g., the Foundation series) where 
plans for new projects can be pre¬ 
sented for criticism; (ii) use of statis¬ 
ticians as members of the committees 
evaluating government-sponsored re¬ 
search; (iii) establishment of task 
forces and advisory panels for large 
projects; and (iv) inclusion of one or 
more statisticians in each field experi¬ 
ment team. 

4. Research in statistical method¬ 
ology applicable to weather modifi¬ 
cation programs should be promoted 


73 



and supported. Such research should 
include: the development and valida¬ 
tion of statistical models; devel¬ 
opment of useful formulations of 
meteorological hypotheses; and inves¬ 
tigations of the statistical characteris¬ 
tics of the measuring instruments used 
in this field. 

5. It is strongly recommended that 
any regulatory agency include as one 
of its technical members or advisors a 
person knowledgeable in statistical 
principles and techniques. 

6. Steps should be taken to work 
out a voluntary system that assures 
that commercial seeding operations 
do not contaminate or vitiate scien¬ 
tific field work carried on in specified 
areas of the country. Furthermore, 
efforts of commercial seeders to 
gather valid evidence on the magni¬ 
tude of seeding effects should be en¬ 
couraged but should not be required 
of commercial cloud seeding opera¬ 
tions. 

PHECinTimOII-ORIEIlIED 

EXPERIMENTS 

A basic source of controversy and 
uncertainty in the field of weather 


modification by cloud seeding has 
been the relative scarcity of “precipi¬ 
tation-oriented” experiments. An ex¬ 
periment is “precipitation-oriented” 
if it provides adequate information 
about ground precipitation in the area 
presumably affected by cloud seeding 
as well as in control areas. The doubts 
concerning conclusions from commer¬ 
cial cloud seeding operations were 
expressed forcefully after the publi¬ 
cation of the report of the Advisory 
Committee on Weather Control. These 
doubts arise from the possibility that 
various forms of selection bias exist, 
as well as biases due to non-linear 
transformations performed on the pre¬ 
cipitation data. Still, no specific source 
of bias has been discovered that 
would account for all of the positive 
findings contained in the recent NAS 
Panel analyses. 

In a field such as weather and cli¬ 
mate modification, the statistical 
methodology of bias elimination be¬ 
comes particularly prominent. Ran¬ 
domization is then naturally in the 
foreground. 

Modern statistical design and eval¬ 
uation are based on a probabilistic 
model intended to present the impor¬ 
tant aspects of the phenomenon being 
studied. The tools of modern proba- 


74 



bility theory are extremely flexible so 
that the underlying probabilistic 
model may be far removed from the 
oversimplified concepts of “random¬ 
ness” in the sense of serial independ¬ 
ence, constancy of probability distri¬ 
bution over time, or rectangularity of 
the probability density function. 

But since experimental resources 
typically limit the obtainable sample 
size or the period of observation, it 
is important not to neglect the power 
of test procedures and other dimen¬ 
sions of statistical efficiency. A multi¬ 
dimensional or profile approach, 
based at least in part on the physical 
theory of the observed phenomena, 
will be particularly effective. 

Among the ultimate aims of a 
planned “precipitation-oriented” ex¬ 
periment must be a contribution to 
the understanding of the mechanism 
by which cloud seeding succeeds or 
fails in influencing ground precipita¬ 
tion. Therefore, the fact that precipi¬ 
tation on the ground is to be carefully 
measured does not exclude the collec¬ 
tion of observations of other physical 
variables. 


THE EMPIRICAL APPROACH 

It has been claimed that answers to 
the weather modification problem can 
only come from basic research. This 
argument suffers from two defects: 

1. There are numerous precedents 
where the effectiveness of human 
action has been empirically estab¬ 
lished beyond reasonable doubt many 
years before any degree of under¬ 
standing of the underlying mechanism 
was attained. Thus, there is no basis 
for claiming that the understanding of 
the underlying atmospheric mecha¬ 
nisms is a necessary condition for a 
determination of effectiveness of 
cloud seeding in generating ground 
precipitation. 

2. Even a complete understanding 
of the causal relations in cloud seed¬ 
ing might fail to answer the question 
of the effectiveness of cloud seeding. 
To answer the latter question on the 
basis of the theory of the underlying 
mechanism, one would still need com¬ 
prehensive information concerning 
the distribution of the initial values 
of the various atmospheric parameters. 
This information is not at present 


75 



available and might be extremely diffi¬ 
cult to come by. 

The basic recommendation is that 
a program of planned field experi¬ 
ments be undertaken, possessing con¬ 
tinuity over a period of 5 to 10 years 
and on a scale sufficient to permit 
geographic comparisons and differen¬ 
tiation, as well as stratification ac¬ 
cording to the type of seeding agent, 
mode of injection, cloud type, etc. 
Provision should be made for the in¬ 
clusion of relevant precipitation data, 
in addition to other relevant physical 
variables. This program should be 
undertaken, designed, and evaluated 
in close association with statisticians 
with extensive experience in experi¬ 
mental design. 

In view of the emphasis on the 
physical aspects of weather modifica¬ 
tion experiments, it is important to 
remember that such experiments pro¬ 
vide a unique opportunity for moni¬ 
toring variables in the realm of 
biology, ecology, and social phenom¬ 
ena related to weather modification. 
Indeed, the design of weather and cli¬ 
mate modification experiments should 
incorporate the needs of these fields. 
Ecologists will provide suggestions as 
to design, making it possible to ob¬ 
serve the effects on various species; 


the social psychologists will provide 
for observations on human perception 
of weather modification activities, and 
the economist will concern himself 
with productivity effects, etc. The 
details of this aspect of experimenta¬ 
tion must be worked out by experts 
in the respective substantive fields, 
but their conclusions will have to be 
carefully considered by the statisti¬ 
cians in guiding the experimental de¬ 
sign. 

MUMERIUl MODELING 
MID SIMULATION 

The techniques of numerical mod¬ 
eling and simulation complement and 
expand the potential of statistical 
analysis. In fact, they are high-pow¬ 
ered substitutes for paper and pencil 
calculation of the behavior of complex 
systems under assumed conditions, 
parameter values, etc. Plausible values 
to be assumed must still be generated 
by empirical research in which statis¬ 
tics is likely to play an important role. 
Modeling and simulation require the 
existence of a mathematical theory of 
the phenomenon, making it possible 
to establish a link between such vari- 


76 



ables as cloud seeding and precipita¬ 
tion. 

When the mathematical model has 
not yet been developed or when 
realistic information on the relevant 
parameter values is not available, 
numerical modeling may not be feas¬ 
ible or fruitful. In such circumstances 
it may still be possible to arrive at the 
empirical relationship between seed¬ 
ing and precipitation by intensive 
systematic randomized and stratified 
field experimentation or by non- 
experimental statistical analysis. 

On the other hand there are situa¬ 
tions, as with large scale circulation 
problems, where field experiments are 
impossible, while a mathematical 
model is available from dynamic 
meteorology and there is information 
on parameter values. Here numerical 
modeling can and should be used. 

In some cases mathematical model 
and parameter information exist, but 
in an incomplete form, while field ex¬ 
periments are possible though diffi¬ 
cult. Here a combination of direct 
statistical analysis together with nu¬ 
merical modeling and simulation may 
be employed to advantage. 


COMMISSION RECOMMENDATIONS 

The Commission recommends: 

1. Statistical training for meteorol¬ 
ogists should be promoted in academic 
programs. Intellectual interchange be¬ 
tween scientists and statisticians 
should be continued through periodic 
seminars. 

2. Statistical consultants should be 
made available to scientists in this 
field through the support of confer¬ 
ences where new projects can be pre¬ 
sented, through use of statisticians as 
evaluators of proposed work, and 
through the support of task forces and 
advisory panels, with statistician 
members, for large projects. Statisti¬ 
cians should aid in the evaluation of 
proposals for government-supported 
research. 

3. Steps should be taken to assure 
that plans for government-supported 
research utilize statistical principles 
in determination of design and size. 

4. Research in methodology should 
be promoted. This includes the de¬ 
velopment and validation of statisti¬ 
cal models, uniformity trials and other 
investigations of the statistical char- 


77 



acteristics of the instrumentation in 
this work. 

5. It is urged that any regulatory 
agency that might come into being 
should have a staff statistician to 
guide efforts to gather valid evidence 
on the magnitude and effects of cloud 
seeding. 

6. A program of carefully planned 
precipitation-oriented field experi¬ 


ments should be carried out under 
complete control of the scientists, 
embodying the required technical 
knowledge, possessing continuity over 
a period needed for conclusiveness, 
and on sufficient scale to permit geo¬ 
graphic conclusions, as well as statis¬ 
tical stratification according to the 
type of seeding agent, mode of injec¬ 
tion, cloud type, etc. 


78 



FOOTNOTE 

1 List of Participants in Conferences 

Baughman, Robert G., Forest Fire Labora¬ 
tory, U. S. Forest Service, Missoula, Mon¬ 
tana 

Bearman, Jacob E., School of Public Health, 
Biostatistics Division, University of Min¬ 
nesota, Minneapolis 

Bigelow, Julien, Institute for Advanced 
Study, Princeton 

Bollay, Eugene, P. O. Box 1022, Boulder, 
Colorado 

Braham, Roscoe, Department of Geophysi¬ 
cal Sciences, University of Chicago 

Brier, Glenn W., U. S. Weather Bureau, 
Washington, D. C. 

Brown, Jr., Byron Wm., School of Public 
Health, Biostatistics Division, University 
of Minnesota, Minneapolis 

Court, Arnold, Department of Geography, 
San Fernando Valley State College, North- 
ridge, California 

Dennis, Arnett, Institute of Atmospheric 
Sciences, South Dakota School of Mines 
and Technology, Rapid City, South Da¬ 
kota 

Grant, Lewis O., Atmospheric Science De¬ 
partment, Colorado State University, Fort 
Collins, Colorado 

Hindman, Ed, Department of Atmospheric 
Science, Colorado State University, Fort 
Collins, Colorado 

Hosier, C. L., Department of Meteorology, 
Pennsylvania State University, University 
Park, Pennsylvania 

Hoyle, Michael, Cloud Physics Laboratory, 
University of Chicago, Chicago, Illinois 

Hurwicz, Leonid, Department of Economics, 
University of Minnesota, Minneapolis 

James, R. C., Bureau of Reclamation, Denver 
Federal Center, Building 53, Denver, Colo¬ 
rado 

Kahan, Archie M., Office of Atmospheric 


Water Resources, Office of Chief Engi¬ 
neer, Bureau of Reclamation, Denver Fed¬ 
eral Center, Building 53, Denver, Colorado 
Kruskal, William, Department of Statistics, 
University of Chicago 

Malone, Thomas F., Research Department, 
The Travelers Insurance Company, 1 
Tower Square, Hartford, Connecticut 
Markovic, Kadmilo D., Civil Engineering 
Department, Colorado State University, 
Fort Collins, Colorado 
Mielke, Paul, Mathematics and Statistics De¬ 
partment, Colorado State University, Fort 
Collins, Colorado 

Peahl, Laurence E., Department of Mathema¬ 
tics, Taft Junior College, Taft, California 
Reinhardt, Howard, Montana State Univer¬ 
sity, Missoula, Montana 
Schleusener, Richard A., Institute of Atmos¬ 
pheric Sciences, South Dakota School of 
Mines and Technology, Rapid City, South 
Dakota 

Simpson, J. M., U. S. Weather Bureau, Wash¬ 
ington, D. C. 

Snyder, Marshall, Department of Statistics, 
University of Chicago 

Tick, Leo J., Data Processing and Computing 
Laboratory, Research Division School of 
Engineering, New York University, Uni¬ 
versity Heights, New York, New York 
Van Ness, John, Department of Statistics, 
Stanford University, Palo Alto, California 
Willis, Paul, E. Bollay Associates, P. O. Box 
N, Steamboat Springs, Colorado 
Wyckoff, P. H., Atmospheric Sciences Sec¬ 
tion, National Science Foundation, Wash¬ 
ington, D. C. 

Yevdjevich, Vunica M., Foothills Research 
Campus, Colorado State University, Fort 
Collins, Colorado 

Youden, W. J., Applied Math Division, Na¬ 
tional Bureau of Standards, Washington, 

D. C. 

Zopf, D., Eugene Bollay Associates, P. O. 
Box N, Steamboat Springs, Colorado 


79 



Like other recent technological ad¬ 
vances, weather and climate modifi¬ 
cation techniques, if fully effective, 
present humanity with unprecedented 
opportunities and grave dangers. So 
pervasive are the elements of weather 
in the mind and works of man that an 
alteration in one of them, even over 
a small area, may provoke intricate 
social changes. Some of these changes 
are obvious but many are difficult to 
trace and puzzling to measure. 

A modification in a small area of 
atmospheric circulation may cause 
shifts in the system of human produc¬ 
tion and communication, as when fog 
dispersal makes possible an airplane 
flight that otherwise would be 
grounded. It also may lead to un¬ 
wanted conditions; thus, the measures 
to dissipate fog may increase the icing 
of highways in the immediate airport 
area. Modification at one place may 
provoke changes in the atmospheric 
circulation elsewhere, as when there 
possibly forms a “rain shadow” of 
decreased rainfall to the detriment of 
a wheat farmer in the lee of an in¬ 
duced increase which brings profit to 
another farmer, or when the weather 
that pleases the wheat rancher causes 
distress to the nearby cherry orchard- 
ist. 


The effects of the modification on 
man’s activities sometimes are direct, 
as in the case of fog dissipation, but 
more often they operate indirectly 
through alterations in the hydrologic 
system or in biological ecosystems. 
Their extent is especially troublesome 
to discover because a sustained pro¬ 
gram of modification would change 
the climatic characteristics, and the 
whole fabric of society, being subtly 
adjusted to climatic means and ex¬ 
tremes, is likely to change with them. 

The gains and losses that follow in 
the train of atmospheric alterations 
accrue to other processes of society 
as well as to economic production and 
consumption. The organization of 
livelihood may be affected, and the 


* The Commission had the benefit of 
thinking contributed by participants in a 
Symposium on Economic and Social As¬ 
pects of Weather Modification held at 
Boulder, Colorado on July 1-3, 1965 by the 
Department of Geography of the University 
of Chicago in collaboration with the Na¬ 
tional Center for Atmospheric Research 
under a grant from the National Science 
Foundation. Papers from that symposium 
shortly will be published in the University 
of Chicago Geography Research Papers 
under the title of Human Dimensions of 
Weather Modification , edited by W. R. Der¬ 
rick Sewell. The list of participants in the 
Symposium appears under Footnote 1 to 
this chapter. Also see the Appendix. 


THE HUMAN 
EFFECTS OF 
WEATHER 
AHD CLIMATE 
MODIFICATION 


80 


quality and enjoyment of life may be 
enhanced or degraded. 

Just how significant these chains of 
events may be on human activity still 
is largely conjectural. A few, such as 
the increase of hydroelectric genera¬ 
tion from induced precipitation in the 
drainage above a power plant may be 
gauged with some confidence. Ac¬ 
cording to some estimates, even highly 
modest precipitation increases at the 
right times in cultivated areas are 
likely to be of major value. The direct 
benefits to agriculture and forestry 
from hail prevention and lightning 
suppression are likely to be significant 
and not too difficult to estimate. Many 
effects cannot be measured readily. To 
the uncertainty of what modification 
is within man’s grasp therefore must 
be added his ignorance of the full 
consequences of whatever modifica¬ 
tion he may achieve. In the face of 
uncertainty as to modification tech¬ 
niques and of doubt as to their social 
effect, a sound public policy encour¬ 
ages research on both techniques and 
effects so as to fully exploit what may 
be an historic opportunity while 
guarding against heavy or irreversible 
damages to society. 

After outlining several basic social 
problems attaching to weather modi¬ 


fication, there are recommended meas¬ 
ures which should be taken by the 
Federal Government to deal with im¬ 
mediate questions of research and 
field operations and to improve the 
nation’s capacity to deal with larger 
questions that loom in the future. 

In canvassing these issues the Com¬ 
mission has drawn on the experience 
and outlook of scientists who have 
worked with modification of other 
aspects of natural resources. There 
has been only a little study of weather 
and climate impacts alone, but the ef¬ 
fects of managing water and land 
yield many relevant lessons. 

The final report of the Advisory 
Committee on Weather Control con¬ 
tained an appendix relating to econ¬ 
omic evaluation. However, it did not 
instigate any concerted effort to im¬ 
prove capacity to measure the human 
effects of weather and climate modifi¬ 
cation. A few thoughtful studies were 
made but the problem was neglected 
for the most part. In making it possi¬ 
ble for workers from anthropology, 
economics, geography, meteorology, 
political science and related fields to 
assess the current state of their 
knowledge, the Commission sought to 
identify points where predictions now 


81 



are practicable and questions deserv¬ 
ing more intensive study. 1 

FOUR MTERLOCKMG SYSTEMS 

It is important to recognize that al¬ 
though man may seek to modify 
weather in order to benefit the quality 
of his life the result is rarely a simple 
relation between an atmospheric con¬ 
dition and human activity in that 
place. Atmospheric circulation, the 
hydrologic cycle, biological ecosys¬ 
tems, and human production are inter¬ 
locked. There may be a direct and 
largely limited connection between at¬ 
mosphere and economic production, 
as with fog dissipation or lightning 
suppression. More often, the benefits 
and costs to the system of production 
and communication are felt indirectly 
through changes in the hydrologic cy¬ 
cle and in biological ecosystems: a 
shift in the atmosphere changes one 
or more of the other three. Thus, an 
increased amount of June rainfall in 
the High Plains of Colorado would 
affect the production of wheat by add¬ 
ing to soil moisture and the capacity 
of plants for transpiration and of soils 
for evaporation. Stream flow and 
ground water supply in the area there¬ 


fore would be altered in some degree, 
however slight. Enlarged wheat har¬ 
vest would be the major outcome but 
by no means the only one. 

As has been shown in the preceding 
chapter, the resulting shifts in eco¬ 
systems of plants, animals, soil, and 
microclimate are exceedingly difficult 
to assess. If they cannot be identified 
fully their long-term significance for 
human activity cannot be gauged. 

Much the same problem is associa¬ 
ted with sectors of the hydrologic 
cycle. Certain changes in stream flow 
which would result from increasing 
precipitation or from decreasing evap- 
otranspiration may be estimated. It 
increasingly is possible to predict the 
modification in stream flow resulting 
from changes in precipitation and tem¬ 
perature. After a soil is saturated a 
small increase in rainfall may cause 
a proportionately larger increase in 
runoff. There is less knowledge about 
the likely effects of such changes on 
the movement of silt downstream, or 
about the relation of rainfall intensity 
to rates of gully cutting in arid regions 
such as the Upper Rio Grande basin. 

Lack of full understanding of the 
consequences has never been a reason 
for man to forbear modifying a part 
of his environment. He does not re- 


82 



frain from ploughing a Carolina field 
because he is ignorant of the full ef¬ 
fects upon soil biota or upon runoff. 
He has not held up the construction 
of storage dams in Kansas because of 
doubt as to the readjustments in chan¬ 
nel cross section and gradient which 
will take place downstream when the 
flow is regularized. Moreover, in seek¬ 
ing to alter the landscape in one way 
he may unwittingly cause damages to 
others. There never is a time in the 
present state of scientific knowledge 
about air, soil, water, plants, and ani¬ 
mals when these changes can be rec¬ 
ognized in all their complexity. To 
defer action until all the consequences 
are tallied up would be to halt all new 
resource management. Yet, there have 
been times when the public decision 
to go ahead in ignorance has led to 
bitter regrets, as when highly erosive 
soils have been ploughed and new cy¬ 
cles of gully cutting have been trig¬ 
gered; or as when channel works have 
caused heavy silting and dislocation 
of downstream drainage systems. 

In considering the possibility of a 
new tool of environmental modifica¬ 
tion which may be coming into man’s 
hands, the challenge is to find a course 
of action which without inhibiting 
largely beneficial results will curb 


those measures which might bring 
serious or irreversible damages to the 
environment. Arriving at such judg¬ 
ments requires not only recognition of 
what is known and not known about 
the atmospheric, hydrologic, and bio¬ 
logical systems affected, but assess¬ 
ment of how a change in one or all of 
them will affect human life and of 
how one kind of change compares 
with another. 

Weather and climate modification is 
distinct from the more conventional 
tools of environmental change in sev¬ 
eral respects. It promises to ordinarily 
affect areas distant from those where 
modification is tried: more than any 
other readily available tool it may ex¬ 
tend its effects across the frontiers of 
countries, states, and nations. Its po¬ 
tentials for provoking local and inter¬ 
national conflict therefore are great. 
It usually has consequences for both 
hydrologic and biological systems. It 
is new. For these reasons there is 
greater likelihood that man at the out¬ 
set will see the gravity as well as the 
exciting opportunity of modification 
measures and that conscious attempts 
will be made to weigh their future 
consequences for society at the local, 
national, and international levels. 
However, the techniques so far devel- 


83 



oped are cheap, readily moved from 
place to place, low in capital invest¬ 
ment, and often free from the hazard 
of irreversible shifts in the atmos¬ 
phere. These reasons tend to stimulate 
small-size operations widely dispersed 
in time and place, and to offset the 
caution that otherwise might apply. 

UNCERTAINTY 

Uncertainty characterizes most 
thinking about the changes in natural 
systems that are subject to modifica¬ 
tion. Not only is there uncertainty 
about how much the atmospheric cir¬ 
culation can be altered and what this 
would mean for the movement and 
quality of water, plants, and animals, 
but the consquences for human pro¬ 
duction and communication are sub¬ 
ject to similar doubt. 

This is one of the factors account¬ 
ing for the casual attention which has 
been given to the social consequences 
of weather and climate modification 
since publication of the report of the 
Advisory Committee on Weather Con¬ 
trol in 1957. An appended paper 
pointed out the need for more syste¬ 
matic examination of the human ef¬ 
fects of modification. Little was done 


thereafter. Doubt as to the possibility 
of changing the weather led scientists 
to ignore the challenge, and they were 
supported in this by the silence of 
the Advisory Committee on Weather 
Control as to the need, by the scepti¬ 
cism of many atmospheric scientists, 
by the debate in the academic com¬ 
munity over the statistical methods 
used in judging cloud-seeding experi¬ 
ments, and by the caution of Federal 
agencies in encouraging new research. 
There was no agency specifically 
charged to look into the human ef¬ 
fects, and within the National Science 
Foundation the responsibility for 
weather modification research was 
lodged in the Section on Atmospheric 
Sciences. 

The principal lesson to be drawn 
from this experience is that where un¬ 
certainty is large, as it continues to be 
with weather and climate modifica¬ 
tion, the basic social implications will 
tend to remain unexplored unless ex¬ 
plicit and sustained effort is made to 
stir up and support the essential re¬ 
search. Otherwise, the human prob¬ 
lems are ignored until they burst into 
prominence on the heels of an im¬ 
provement in technique. 

Where uncertainty is high there is 
much in favor of a public strategy 


84 



which promotes diversification of ef¬ 
forts rather than dependence upon 
one line of action or research. Not 
only would this call for pursuit of 
studies on a variety of physical pro¬ 
cesses, but it would suggest that the 
needs for and damages from theoreti¬ 
cally possible modification would be 
examined in advance of perfection of 
techniques. In promoting a strategy 
of diversification it is important, how¬ 
ever, to avoid spreading the research 
so thinly that no one project is re¬ 
warding. Allocation of funds among 
different aspects of modification pre¬ 
sumes a rough judgment of what kinds 
of changes would be desirable in im¬ 
proving the quality of human life. 

TWO APPROACHES TO THE 
HOMAN DIMENSIONS 

Investigation of the human dimen¬ 
sions of weather modification can 
move along either one of two lines. 
A possible modification, such as pre¬ 
cipitation induction or lightning sup¬ 
pression, can be assumed and then an 
effort made to estimate what the con¬ 
sequences would be in the society. 
Where a modification is tried, as in 


seeding above a hydroelectric plant, 
the effects upon power production 
downstream and in the generating 
network may be traced. A variant is 
to assess the effect of rare meteorolo¬ 
gical events. A second approach is to 
ask at what points the social system 
would be sensitive to a change in 
weather conditions, and from this to 
estimate what would be the more de¬ 
sirable and undesirable changes which 
might be foreseen without regard to 
whether or not they currently are 
practicable. 

Under the first approach, the atten¬ 
tion is directed toward discerning the 
likely impacts of modification which 
promise early achievement. Under the 
second, the emphasis is on types of 
modification which should be sought 
or avoided. The two approaches are 
not mutually exclusive, and they can 
helpfully supplement each other. Both 
are recommended for early action. 

NROADEN CONSIDERATIONS 

Whether emphasis is upon fore¬ 
casting effects of practicable modifi¬ 
cation measures or upon points in so¬ 
ciety which would be more sensitive 
to weather changes, there is doubt 


as to how far man properly should go 
in tampering with atmospheric sys¬ 
tems unless he is relatively clear as to 
the major consequences. Concern 
with growing world population needs 
heightens the interest in gains from 
the weather. Doubt as to human im¬ 
plications as illustrated by the diffi¬ 
culty of assessing results of nuclear 
experiments, has raised new cautions 
concerning any novel or large-scale 
interference with our environment. 
Great prudence is therefore warranted 
in practicing weather modification, 
and increased support is desirable to 
explore its side effects, as well as its 
ability to achieve the desired results. 

Deep in human experience is a sense 
of excitement and beauty in coping 
with the extremes of wind and rain 
and heat. To be sure, their enjoyment 
does not always offset the discomfort 
and suffering that lead men to com¬ 
monly adjust their clothing, dwellings, 
transport and other practices to curb 
the effects of weather. Yet in the driv¬ 
ing power of a winter blizzard or the 
sudden flash of summer lightning 
there are dramatic reminders of the 
elemental forces with which the hu¬ 
man race constantly is striving to find 
its place. No presently conceivable 
program of weather or climate modi¬ 


fication could eliminate these ex¬ 
tremes. A beginning at changing storm 
or lightning nevertheless raises the 
question of how far the human spirit 
is enriched by the uncertainty and 
wonder and exhilaration that come 
with the restless, violent movements 
of the atmosphere. Any effort to as¬ 
sess the social consequences of 
weather and climate modification must 
give weight to the esthetic and spirit¬ 
ual as well as purely material rewards. 

EVALUATING SOCIAL EFFECTS 

The keen interest in precipitation 
induction and fog dispersal shows 
that their direct results are believed 
to be highly beneficial. Certain elec¬ 
tric power utilities, airlines, and fruit 
growers have invested funds in re¬ 
search and operations directed at 
practical modifications. A public util¬ 
ity on the Pacific Coast concluded that 
in the drainage area of one of its res¬ 
ervoirs an increase of less than two 
percent in annual precipitation would 
clearly justify cloud seeding and that 
an increase of ten percent for a large 
watershed might be worth $200,000. 
An airline has estimated that the im¬ 
mediate benefits in reduction of oper- 


86 



ating expenses from fog dispersal in 
an intermountain area were at least 
five times the seeding costs. Ob¬ 
viously, if a farmer thinks he may in¬ 
crease his per acre wheat yield from 
seven to eight bushels by rainfall in¬ 
duction or hail suppression at a cost 
of a few cents an acre he will be 
strongly inclined to take the risk of 
the expenditure even though the re¬ 
sults are in doubt. It has been calcu¬ 
lated that the estimated mean annual 
losses of $250,000,000 from hurricanes 
might be reduced by as much as one 
third if only modest reductions in 
storm intensity or slight changes in 
storm paths could be achieved. Op¬ 
portunities for direct, beneficial ef¬ 
fects in the economy are immense in¬ 
sofar as genuine modification can be 
managed with confidence. The meth¬ 
ods for computing such direct benefits 
are relatively well developed. 

In the sphere of human activities, 
the potential effects of modification 
on the quantity, timing, and geo¬ 
graphic distribution of production and 
transportation are particularly strik¬ 
ing. But in evaluating the social effects 
of weather modification it is not 
enough to trace them through the tech¬ 
nological aspects of production activi¬ 
ties. Behavorial responses and their 


relation to the impact on social organ¬ 
ization and process must also be iden¬ 
tified. Because weather modification 
involves costs and may preclude al¬ 
ternatives, its possible results must 
be compared with achievements ob¬ 
tainable through alternative ways of 
dealing with the vagaries and averages 
of weather phenomena. Man adjusts 
his activities to weather in countless 
ways and constantly is devising new 
ones. The evaluation of fog dissipa¬ 
tion requires not only the measure¬ 
ment of benefits and costs at the air¬ 
port and in airline operations, but the 
assessment of the benefits and costs 
from installing equipment which could 
land aircraft notwithstanding fog or 
from re-routing traffic on the ground 
and in the air. 

Improved weather forecasts are one 
major alternative to weather modifi¬ 
cation. Sometimes they may comple¬ 
ment each other, but in many instances 
an accurate forecast with sufficient 
advance warning, if accompanied 
by other measures, would reduce or 
even eliminate the gains from altering 
a weather extreme. Thus, as much as 
15-20 percent of flood losses may be 
eliminated in certain areas, if there is 
sufficient notice, without changing the 
character of the flood or of the pre- 


87 



cipitation producing it. Severe crop 
losses from drought may be reduced 
by alternate cropping if the drought 
can be predicted sufficiently far in 
advance. Traffic can be re-routed 
around airports which will be closed 
by fog. Perhaps no industry is more 
carefully prepared to take advantage 
of a forecast of icy or freezing weather 
than is the public utility industry 
which can move promptly to cope 
with weather emergencies. Inaccurate 
forecasts also may cost heavily in 
damages. 

Even in the absence of significant 
forecasting improvements, there are 
many other means of cutting down 
dislocations caused by weather. In 
areas where drought occasionally 
brings acute crop losses, the social 
impacts may be curbed by readjust¬ 
ment in cropping patterns, by breed¬ 
ing or selecting drought resistant vari¬ 
eties of plants, by supplementing the 
water supply, by insurance schemes, 
and by a variety of other actions, some 
of which depend upon further scien¬ 
tific research for their perfection. A 
similar range of solutions applies to 
dislocations caused by hail, excessive 
rain, fog, and lightning. 

To be realistic, measurement of the 
benefits and cost of modification, fore¬ 


casting, or any of the other alternatives 
must take into account the likelihood 
that if certain of them are pursued 
consistently, the structure of the econ¬ 
omy will change so that it becomes 
less vulnerable to dislocation by 
weather. In drought areas a reor¬ 
ganization of farming practices might 
lead to agriculture which would be 
less vulnerable to the recurring dry 
periods. Or, a continuing program of 
cloud seeding, if practicable, might 
raise the mean rainfall sufficiently to 
encourage a major revision in type of 
farming. This, in turn, could shift the 
service functions of nearby urban cen¬ 
ters. 

Without any conscious modification 
of weather, the sensitivity of human 
activity to weather may be reduced, 
as when air conditioning or insulation 
of utility lines renders an area less 
susceptible to extremes of tempera¬ 
ture. During 1929-1962, the yield of 
corn in the Corn Belt increased in sev¬ 
eral steps related to the technology 
of seed, cultivation, and fertilization, 
but during the same period the vari¬ 
ation in yields due to weather ap¬ 
peared to decrease. 2 That is, the crop 
production became less susceptible to 
weather dislocations. In these and 
other ways estimates of direct im- 


pacts of weather modification must be 
corrected for longer-term structural 
adjustments. 

Research relating to the social im¬ 
pact of weather on human affairs 
would prove fruitful even if no form 
of weather or climate modification 
were ever to be achieved. Deepened 
understanding of geographic relation¬ 
ships among weather characteristics 
and the economic system would be 
bound to aid in intelligent decisions 
by both resource users and public 
agencies in agriculture, transport, 
manufacturing, and other sectors of 
the economy. The kind of refined 
knowledge about crops and rainfall, 
or air transport and fog, or forest 
growth and lightning which would be 
essential to careful estimates of social 
impacts of weather modification would 
be required for estimates of the sen¬ 
sitivity of the economy to weather, 
or for improvement in efficiency of 
those activities by other means. 

One fundamental question deserv¬ 
ing scientific attention is the degree 
to which climate already has been 
altered or may be altered in the future 
inadvertently by the hand of man. To 
the extent that either rural or urban 
climates have been so modified, the 
type and distribution of human ac¬ 


tivity may be expected to reflect some 
readjustments that now are taken for 
granted. Urban climates have under¬ 
gone measureable change in tempera¬ 
ture and air quality. The precise 
amount still is in doubt. While few 
modern societies are so delicately ad¬ 
justed to rain or its invocation as are 
certain of the organizations and social 
controls of Pueblo culture in the 
Southwestern United States, all of 
them involve many adaptations. 

Whether the relations of weather 
to human activity are isolated over a 
few days or many years, they ob¬ 
viously are different from one sector 
of society to another. The downpour 
which fills a New York city reservoir 
washes gullies in a farmer’s field; the 
hurricane which disrupts a Florida 
shopping center carries water to a 
nearby Everglades wildlife refuge. If 
it is assumed that there is any effect 
upon processes elsewhere, the differ¬ 
ential results become even more 
marked. Were cloud seeding to have a 
“rain shadow” of lowered precipita¬ 
tion or were hail suppression to re¬ 
duce rainfall to the leeward, the com¬ 
plications would multiply. If it were 
to be shown that cirrus cloud forma¬ 
tion encourages smog conditions, then 
the health and heat budget of a metro- 


politan area might be affected by air¬ 
line operations upwind. A map show¬ 
ing the area where weather elements 
are altered presents only a part of the 
picture; it must delimit the extent of 
effects felt in nearby towns or in dis¬ 
tant markets. 

These impacts are made especially 
difficult to measure because people 
may differ in their perception of 
weather conditions and of man’s ef¬ 
fect upon weather. Just as many city 
dwellers in the path of a hurricane 
are unable to act rationally on the 
warning of high winds, so people in 
an area of weather modification may 
for a variety of reasons fail to take 
advantage of a changed condition. On 
the other hand, a farmer may act as 
though the weather is being modified 
even when scientific verification is 
lacking. In either case, the estimate 
of the individually and socially ra¬ 
tional solution does not turn out to 
describe what people in fact do. A 
workable public policy is based on 
prediction of what they will decide in 
practical situations. The uneasy sus¬ 
picion of a nation that it is suffering 
from cloud seeding to the windward 
is a political reality that must be faced 
seriously, whether or not harmful ef¬ 
fects are known to occur. 


Judgment as to adoption of econom¬ 
ically optimum solutions inevitably 
is tempered by appraisal of what is 
likely to unfold in daily activities 
once the alteration is under way. It 
may well be that individuals will be 
unable to take advantage of the poten¬ 
tial benefits of weather and climate 
modification unless legal and institu¬ 
tional changes are put into effect. 

CONFLICTS OF INTEREST 

Even though there is no confident 
prediction of the extent to which 
weather and climate may be modified 
in the future or of the full chain of 
impacts from such modification, it al¬ 
ready is evident that at least four 
types of conflicts may be expected to 
arise as soon as a modification tech¬ 
nique is shown to be practicable. In¬ 
deed, they will arise whenever there 
is any slight ground to think it may be 
practicable. Substantial groups in the 
nation already believe cloud seeding 
produces rain and perhaps even rain- 
shadow; their responses to private 
seeding operations or government re¬ 
search programs are based on these 
beliefs and range from enthusiasm to 
hostility. 


90 



These perceived conflicts are real in 
the minds of the people involved, and 
they cannot be ignored because they 
lack scientific validation. This is par¬ 
ticularly true of the conflicts believed 
to extend across political boundaries. 
Below are examples of possible areas 
of conflict. 

1. Research on the techniques of 
weather modification is likely to en¬ 
counter conflict with other research 
programs unless there is clear agree¬ 
ment as to the time and place of each 
field experiment. Otherwise, opera¬ 
tions in the area may cause contam¬ 
ination and thus run the risk of in¬ 
validating the observations elsewhere. 

2. A proliferation of weather modi¬ 
fication operations could make it im¬ 
possible to carry out carefully con¬ 
trolled experiments. Were farmers in 
the Great Plains to become generally 
convinced that cloud seeding could 
increase rainfall at critical periods or 
could suppress hail, their activities 
soon would cover the area so 
thoroughly that without regulation it 
would be difficult to run experiments 
to find out whether or not the opera¬ 
tions were in fact effective. 

3. A conflict arises where one group 
stands to benefit from weather modi¬ 


fication and another to lose. As al¬ 
ready noted, this may apply both 
within a single area and between two 
areas. 

4. There is the possibility of con¬ 
flicts between groups seeking to mod¬ 
ify weather for different purposes or 
for the benefit of different areas. 
Rather than there being unintended 
effects upon other groups from one 
seeding operation, there can be direct 
conflict over the use of a site or 
atmospheric condition. 

Public policy should recognize the 
probability that all four types of con¬ 
flict may arise, and should seek to 
reconcile each of them equitably. In 
that effort its responsibility goes far 
beyond arbitrating conflict. It should 
seek to prevent victimization, either 
of people who mistakenly think they 
are gaining benefits that do not exist 
or of people who are unaware of dam¬ 
ages being inflicted upon them by 
others. Without public intervention to 
assure that proper records are kept 
and the findings are available to the 
interested parties, it will be impossible 
to determine the true gains and losses. 

It may be necessary that the govern¬ 
ment judge the consequences, pro- 


91 



vided it is certain that suitable 
information is collected. 

In a situation where so much of the 
knowledge is speculative, it is im¬ 
portant that channels be kept open for 
research and for the sharing of re¬ 
search findings. This is especially im¬ 
portant where the social effects may 
possibly reach across county, State, or 
international borders. A policy of pas¬ 
sively waiting for the conflicts to arise 
will in the long run exacerbate them 
by permitting research to be impeded 
and by allowing the alledged injuries 
to show in tedious inconclusive judi¬ 
cial action or in peremptory legisla¬ 
tive fiat. The time to guard against 
groundless contention is before it 
arises. 

A university scientist who is anx¬ 
ious to experiment with cloud seeding 
now feels more cautious than might 
be socially or scientifically desirable 
about launching field work. If he 
shows positive effects he or his insti¬ 
tution may be subject to damage suits 
from those who think they have been 
injured by too much rainfall or by too 
little or by rainfall at the wrong time. 
Even if his results are negative or in¬ 
conclusive, he still may be open to 
legal attack by those who genuinely 
feel themselves disadvantaged. 


Insofar as practical modifications 
are carried out they are likely to result 
not only in specific gains and losses, 
but in widespread institutional changes 
in society. Thus far, the conflicts have 
applied to small areas but in the future 
they may extend over large areas. The 
readjustments which result therefrom 
will call for major changes in policy 
and organization as well as for arbi¬ 
tration of competing claims and dam¬ 
ages. 

DESIRABLE COURSES Of ACTION 
Analysis ol social impacts 

Because of the need for determin¬ 
ing more precisely the character of 
social consequences of weather mod¬ 
ification, it is important that any 
further government operations and 
government supported research deal¬ 
ing with modification be accompanied 
by analysis of those consequences. If 
the operations are entirely private, it 
would be desirable for the public to 
underwrite such analysis so that the 
social results could be recognized. 

In cases where the operations are 
in relatively small areas and do not 
induce structural changes in the econ- 


92 


omy, the methods of measuring im¬ 
pacts may be adapted, with suitable 
changes, from Federal experience with 
evaluating water development proj¬ 
ects. Much useful work has been done 
on gauging benefits and costs from a 
change in water occurrence. These 
methods will not be readily applicable 
to such special questions as the as¬ 
sessment of recreation benefits and 
the distribution of benefits and costs 
outside the target area. Nor will they 
be particularly helpful in recognizing 
institutional adjustments that would 
be prominently involved in sustained 
modification operations. The findings 
would be rough, but they would give 
an idea of the order of magnitude of 
results and would suggest problems of 
evaluation deserving early attention. 
Much can be learned promptly from 
studying the economic aspects of legal 
conflicts which already have arisen. 

If Federal and private agencies are 
not ready to undertake this type of 
analysis, the National Science Foun¬ 
dation should be prepared to support 
it. After a few years, the analysis 
might be attempted more selectively. 
At present, it should be tried wher¬ 
ever practicable. 



There should be critical review of 
the methods followed and of the find¬ 
ings so that the methods might be 
improved and in time made uniform. 
It would be a mistake at this stage to 
attempt to set standards for social 
evaluation of weather modification. 
At present there is no guarantee that 
the analyses of different aspects 
could be compared with one another. 
Working from the experience with 
interagency cooperation in water re¬ 
source studies, the Foundation should 
convene a panel of representatives 
from interested public agencies and 
from research institutions to examine 
analytical methods and to suggest 
ways of refining them. The panel 
would be expected to appraise meth¬ 
ods used for the ^identification and 
measurement of impacts and the use 
of such evidence in evaluating weather 
modification and alternative measures. 
It could draw heavily from experience 
over the past two decades in attempt¬ 
ing to gauge the effects of water proj¬ 
ects on farming, nearby towns, and 
on more distant areas. It would report 
its findings to the Foundation and the 
interested agencies, then making pub- 


93 


lie its evaluations. At an early time, it 
might well use the data from one of 
the comprehensive river basin studies, 
such as the Delaware Basin study, to 
test the suitability of the methods in 
common use. 

Research on social [fleets 

The support and encouragement 
which the National Science Founda¬ 
tion has given to research on physical 
processes of the atmosphere should be 
extended to research on those rela¬ 
tions between weather and human ac¬ 
tivity which possibly would be 
affected by weather modification. This 
should include the nature of external 
economies and diseconomies from 
modification operations, the conse¬ 
quences of shifts in ecosystems, and 
the institutional changes that may re¬ 
sult. Methods for measuring changes 
in crop production and the losses 
from fires are well developed, but im¬ 
pacts on recreation and on biological 
communities are rough at best. Many 
of the impacts will show in revision 
of organization of individual and com¬ 
munity enterprises. 

One means of stimulating further 
thinking about fruitful approaches to 


these and related problems would be 
to enable a scholar broadly acquainted 
with the social sciences to spend a 
year examining the field of weather 
modification with a view to suggesting 
especially difficult or promising lines 
of investigation. So little systematic 
work has been done to date, beyond 
the interdisciplinary exchanges al¬ 
ready instigated by this Commission, 
that it would be helpful to have a 
more thorough appraisal of oppor¬ 
tunities. The exploratory studies of 
weather information and prediction 
by the U. S. Weather Bureau and the 
Rand Corporation, and the scattered 
economic and geographic investiga¬ 
tions of the relation of climate to 
farming, commerce, and transporta¬ 
tion need to be extended widely . 3 

It should be emphasized that virtu¬ 
ally all of the research which would 
be initiated would, if sound, yield 
findings that would be useful in mak¬ 
ing more efficient adjustments to 
weather conditions even if no modifi¬ 
cation were ever to be practiced. The 
same method for estimating the bene¬ 
fits to a manufacturer from a change 
in occurrence of rainfall would be 
helpful in calculating the gains from 
an improved rainfall forecast or from 
a technical innovation that would 


94 



render him less vulnerable to damages 
from intense rainfall. 

Fraedom lor ExptManon 

In order to permit field experiments 
with methods that do not threaten 
seriously deleterious results, it is es¬ 
sential to provide for indemnification 
of investigators supported by Federal 
funds against damage suits. 

Research on Basic Relationships 

If there were relatively full under¬ 
standing of the complex relationships 
among weather characteristics and 
human activity, the task of estimating 
impacts of weather modification 
would be more nearly straightfor¬ 
ward. Lacking such understanding in 
all sectors of society, efforts should 
be encouraged to discover them. In 
the long run, it might be practicable 
to develop a model of the national 
economy which would be sufficiently 
detailed and sensitive to predict the 
effects of varying one or more of the 
daily weather inputs. The methodo¬ 
logical problems are enormous. Meas¬ 
urement of weather conditions other 


than precipitation and incoming radia¬ 
tion is difficult in any event. The 
analysis must be developed in prob¬ 
abilistic terms, and the present rela¬ 
tionship to human activity must be 
investigated with sufficient precision 
to permit judgment as to the degree 
to which prevailing geographic pat¬ 
terns of farming, transportation, in¬ 
dustry, and recreation would be 
altered in response to a change in 
weather characteristics. 

In the near future, it would be de¬ 
sirable to explore types of models 
which might be used and the data 
understanding which they would re¬ 
quire. An activity analysis type of 
model might well provide a flexible 
framework without pre-judging the 
nature of relationships to be investi¬ 
gated. An input-output model would 
merit investigation but would offer 
complications. Whatever the form of 
model selected, considerable empiri¬ 
cal study would be required in narrow 
sectors before its application to larger 
parts of the economy would be war¬ 
ranted. Thus, the possible shifts in 
cropping and manufacturing locations 
would need to be specified for differ¬ 
ent magnitudes of change in each 
weather element. Cautious but vigor- 


95 


ous steps should be taken in this di¬ 
rection. 

Research on Decision Processes 

Both the nature of weather proc¬ 
esses and the current knowledge 
about them require that most human 
decisions as to weather modification 
must be made in the face of uncer¬ 
tainty. This imposes special restraints 
on public agencies and it increases the 
difficulty of predicting how individual 
farmers, manufacturers, and others 
who are directly affected by weather 
would respond to changes in weather 
characteristics. There is little evidence 
as to how many people would take 
advantage of an alteration in weather 
even if it could be assured, or that 
they would do so in an economically 
efficient manner. A flood-plain dweller 
may fail to heed an accurate flood 
forecast because he does not under¬ 
stand what practical steps he could 
take; a farmer may not take advantage 
of increased rainfall because condi¬ 
tions of credit or farm organization 
discourage him. It appears that people 
vary from place to place in their belief 
in the effectiveness of weather modifi¬ 
cation. As in all areas of human en¬ 


deavor, there is likely to be a lag 
between technical knowledge and its 
application. Differences according to 
culture groups may be expected. Re¬ 
search on the conditions of decision 
making in these circumstances would 
illuminate discussion of suitable pub¬ 
lic policy by showing the choices that 
are open to public agencies and by 
increasing the ability to predict the 
ways in which weather users may re¬ 
spond to the unfolding technology of 
weather modification. The National 
Science Foundation should encourage 
such investigations. 

Research on inadvertent 
MndiMons 

Although public interest tends to 
concentrate on the possibility and 
effect of new techniques for conscious 
modification of weather, it is desir¬ 
able to look into the degree to which 
past and present human activities 
cause inadvertent changes in weather 
and climate. Investigations of those 
alterations require the collaboration 
of scientists working on atmospheric, 
biological, hydrological, and social 
problems. Historical and archeological 


96 



evidence may need to be compared 
with current geography and with me¬ 
teorological data. The train of events 
between human action and weather 
characteristics should be traced with 
attention not only to physical altera¬ 
tions in climate, but to resulting modi¬ 
fication in the quality of human life. 


lECOMMEMUIIOIIS 

The Commission recommends: 

1. Steps should be taken to assure 
that wherever field experimentation 
or commercial operations are under¬ 
taken in weather and climate modifi¬ 
cation arrangements be made to study 
the social consequences. 

2. A special panel should be estab¬ 
lished to exchange and give critical 
review to the results of such studies. 


3. The method of assessing impacts 
of weather modification should be the 
subject of research looking to its re¬ 
finement and extension. 

4. Freedom of field experimentation 
should be supported by providing in¬ 
demnification of Federally financed 
experimenters against damage claims. 

5. Research should be encouraged 
on the basic relationships between 
weather characteristics and human 
activity. 

6. Decision making processes in the 
face of uncertainty as to weather 
modication and its effects should be 
subjected to careful investigation as 
a means of increasing the govern¬ 
ment’s ability to predict the results of 
alternative policies and methods for 
weather modification. 

7. Interdisciplinary study of modifi¬ 
cations which man makes inadvert¬ 
ently should be encouraged. 


97 


FOOTNOTES 


1 Symposium on the Economic and Social 
Aspects of Weather Modification, July 1-3, 
1965. List of participants: 

Edward A. Ackerman, Carnegie Institution 
of Washington 

Jack Barrows, U. S. Forest Service, Depart¬ 
ment of Agriculture 

Marston Bates, Department of Zoology, Uni¬ 
versity of Michigan 

Boynton Beckwith, Assistant Director of 
Meteorology, United Airlines 
Sherman W. Betts, Interdepartmental Com¬ 
mittee for Atmospheric Sciences 
Carl von E. Bickert, Industrial Economics 
Division, Denver Research Institute 
Reid Bryson, Department of Meteorology, 
University of Wisconsin 
Horace Byers, Department of Geophysics, 
University of Chicago 

Emery N. Castle, Department of Agricultural 
Economics, Oregon State University 
A. R. Chamberlain, Vice President, Colorado 
State University 

Marion Clawson, Resources for the Future, 
Inc. 

Norman Crawford, Department of Civil En¬ 
gineering, Stanford University 
James A. Crutchfield, Department of Eco¬ 
nomics, University of Washington 
Leslie Curry, Department of Geography, 
University of Toronto 

Donald L. Eberly, Meteorologist, Pacific Gas 
and Electric Co. 

Robert D. Elliott, President, North American 
Weather Consultants 

William Garrison, Department of Geogra¬ 
phy, Northwestern University 
Donald L. Gilman, Extended Forecast Divi¬ 
sion, U. S. Weather Bureau 


Lester Goldner, Division of Air Pollution, 
U. S. Department of Health, Education 
and Welfare 

Ivars Gutmanis, Division of Air Pollution, 
U. S. Department of Health, Education 
and Welfare 

Robert L. Hendrick, Senior Research Scien¬ 
tist, Travelers Research Center 
James Hibbs, U. S. Weather Bureau, Depart¬ 
ment of Commerce 

Howard Hines, Director, Division of Social 
Sciences, National Science Foundation 
Leonid Hurwicz, Department of Economics, 
University of Minnesota 
Paul Julian, National Center for Atmos¬ 
pheric Research 

Archie Kahan, Bureau of Reclamation, U. S. 

Department of Interior 
Robert W. Kates, Graduate School of Geog¬ 
raphy, Clark University 
John W. Kirkbride, Statistical Reporting 
Service, U. S. Department of Agriculture 
R. Koopmans, Department of Economics, 
Yale University 

Robert Lucas, Lake States Forest Expt. Sta¬ 
tion, University of Minnesota 
Fremont J. Lyden, Department of Political 
Science, University of Washington 
Arthur Maass, Water Resources Center, 
Harvard University 

Marion E. Marts, Vice Provost, University of 
Washington 

Richard Meier, School of Natural Resources, 
University of Michigan 
Gilbert F. White, Department of Geography, 
University of Chicago 
Donald Michael, Institute for Policy Studies 
Edward A. Morris, Bronson, Bronson & 
McKinnon 

Jack C. Oppenheimer, Executive Secretary, 
Special Commission on Weather Modifi¬ 
cation 

Allan Pred, Department of Geography, Uni¬ 
versity of California 


98 



Reginald C. Price, Deputy Director, State of 
California, Department of Water Resources 
Walter Orr Roberts, National Center for At¬ 
mospheric Research 

Thomas Saarinen, Department of Geogra¬ 
phy, University of Chicago 
Richard Schleusener, Director, Institute of 
Atmospheric Sciences, South Dakota 
School of Mines and Technology 
Anthony Scott, Department of Economics, 
University of Chicago 

W. R. Derrick Sewell, Department of Geog¬ 
raphy, University of Chicago 
Bernard Silverman, Meteorologist, U.S.A.F. 
Meteorological Lab. 

Stephen C. Smith, Department of Agricul¬ 
tural Economics, Colorado State Univer¬ 
sity 

Evon Z. Vogt, Curator, Middle American 
Ethnology, Harvard University 
Andrew Wilson, Department of Geogra¬ 
phy, University of Arizona 
Peter H. Wyckoff, Director, Weather Modi¬ 
fication Program, National Science Foun¬ 
dation 

The problems of measuring the impacts of 
weather modification were examined against 
the background of experience with evalu¬ 
ating water management projects with a 
group of consultants consisting of Emery 
Castle of Oregon State University, Allen 
Kneese of Resources for the Future, W. R. 
Derrick Sewell of the University of Chicago, 
and Stephen C. Smith of Colorado State 
University. Useful suggestions also came 
from a discussion of social evaluation of 
weather modification experiments and op¬ 
erations held in Washington, D. C. on Sep¬ 
tember 20, 1965. Those participating in this 
discussion were as follows: 

Gilbert F. White, University of Chicago, 
Chairman 

Keith Arnold, U. S. Forest Service 


Lowell Ashby, Department of Commerce 
Jack Barrows, U. S. Forest Service 
Robert Cain, National Science Foundation 
Emery N. Castle, Oregon State University 
Frank Hersman, National Science Founda¬ 
tion 

James Hibbs, U. S. Weather Bureau 
Howard Hines, National Science Foundation 
H. R. Josephson, U. S. Forest Service 
Allen Kneese, Resources for the Future 
Karl Lee, U. S. Bureau of Reclamation 
Hoyt Lemons, Department of Defense 
Jack C. Oppenheimer, National Science 

Foundation 

Truman Price, Department of the Interior 
Louis Quam, Office of Naval Research 
Stephen C. Smith, Colorado State University 
Harry A. Steele, Department of Agriculture 
Peter H. Wyckoff, National Science Founda¬ 
tion 

The question of how the basic relations 
among weather and economic activity might 
be investigated through a comprehensive 
model was outlined by Edward A. Acker¬ 
man of the Carnegie Institution of Washing¬ 
ton and was the subject of a special review 
by John A. Edwards of Oregon State Uni¬ 
versity. 

2 Lawrence H. Shaw and Donald D. Du- 
rost, “The Effect of Water and Technology 
on Corn Yields in the Corn Belt, 1929-62,“ 
Agricultural Economic Report, No. 80, Wash¬ 
ington: U. S. Department of Agriculture, 
1965. 

3 R. R. Rapp and R. E. Huscke, Weather 
Information: Its Uses, Actual and Potential, 
Santa Monica: Rand Corporation, 1964. 
Memo RM-4083-USWB U. S. Weather Bu¬ 
reau, The National Research Effort on Im¬ 
proved Weather Description and Prediction 
for Social and Economic Purposes, Wash¬ 
ington, 1964. 


99 


The drawing of conclusions as to 
the legal and legislative aspects of 
weather modification is hampered by 
uncertainty as to the scientific capa¬ 
bilities in the field. If one possessed 
or seemed likely to possess in the near 
future the technological capability of 
ordering weather, the ramifications to 
our society and hence to our legal 
system would be enormous. Even a 
limited capacity to modify weather 
would pose problems of great com¬ 
plexity. The nature of these problems 
is illustrated by what might result if 
the present experiments in the “dis¬ 
arming” of hurricanes are successful. 
At first blush one would suppose that 
no one could object to the dissipation 
of destructive storms such as hurri¬ 
canes. However, there seems to be at 
least some opinion that a substantial 
amount of the rainfall in the North¬ 
east comes about as a result of hurri¬ 
cane activity. It might, then, turn out 
that hurricanes are a necessary part 
of the distribution of rainfall in a sub¬ 
stantial section of the United States. 
Assuming both the power to dissipate 
hurricanes and the need for rainfall 
in the Northeast, how is the decision 
between the risk of catastrophic 
storms and the ending of the drought 
to be made? 


Similarly difficult problems of choice 
will be posed by even the limited 
capability of precipitation induction 
now visualized. In a sense, ability to 
control the atmosphere may create 
more problems than it solves. For na¬ 
tions as well as individuals the avail¬ 
ability of alternatives may turn out 
to be more disruptive than the hard¬ 
ships of want. 

Given the present state of the art, 
extended speculation as to the neces¬ 
sary responses of the laws would seem 
unwarranted in a report of this kind. 
The temptation is strong to put aside 

In considering this facet of the problem 
the Commission addressed questionnaires to 
the 50 state governments and to the 64 per¬ 
sons or organizations (including 7 Federal 
agencies) who have been conducting weather 
modification research activities or commer¬ 
cial operations. The National Science Foun¬ 
dation contracted with the Southern Meth¬ 
odist University School of Law to have Prof. 
Howard J. Taubenfeld undertake in coopera¬ 
tion with the Commission’s Executive Sec¬ 
retary, Jack C. Oppenheimer, Esq., a survey, 
analysis and summary of the data contained 
in the responses. The result is the report to 
be published by the NSF in January, 1966, 
entitled “Weather Modification: Law, Con¬ 
trols, Operations” (see the Appendix). This 
chapter is in large part based upon this 
study. Acknowledgment is also made to the 
helpful suggestions of NSF General Counsel 
William J. Hoff, Deputy General Counsel 
Charles B. Ruttenberg, and attorney Joseph 
R. Schurman. 


LEGAL AND 
LEGISLATIVE 
ASPECTS 


100 



the legal question until the science 
and technology have developed a little 
more. On the other hand, with the 
apparent ability to modify weather 
intentionally, albeit to a limited ex¬ 
tent, and since it is not certain that 
efforts do not result in some unin¬ 
tended modifications, one cannot 
wholly dismiss the problems. More¬ 
over, whatever the scientific truth may 
be, weather modification activities are 
being conducted and many people 
believe those activities have effects 
both beneficial and deleterious. In¬ 
deed, some twenty-two states have 
already enacted legislation dealing 
with those activities. The result is 
that the law is already involved with 
weather modification in many ways, 
so that for better or worse considera¬ 
tion must now be given to some of the 
legal aspects of weather and climate 
modification. 

The existing involvment of weather 
modification with law is, broadly 
speaking, of two kinds: (1) the body of 
rules governing the responsibilities 
and liabilities of weather modifiers (or 
those who employ their services) to 
other members of the public; and (2) 
regulation by government (most often 
by the states) of weather modification 
activities. 


Weather modification activities can 
result in two more or less distinct 
kinds of injury to members of the 
public. The first kind is damage caused 
by destructive weather conditions 
such as flood, hail, hurricanes and the 
like. Damages attributable to such 
conditions, assuming satisfaction of 
other prerequisites to recovery, would 
be compensable under traditional 
standards. The second kind would 
result from the change in climate of a 
particular locality, e.g., lowering or 
raising the level of rainfall in a local¬ 
ity below or above that which would 
have fallen but for the modification. 
Assuming that the level which would 
have fallen naturally could be estab¬ 
lished, damage could be of widely 
diverse kinds; from the blighting of a 
resort owner’s season to the ruining 
of a particular crop.* 

Although liability for weather modi¬ 
fication activities, and “property in¬ 
terests in weather,” have been the 
subject of a good deal of speculation 
in the legal literature, there have been 
only six lawsuits in which the ques¬ 
tions have been litigated. Of these, 
three were suits by nearby land- 

* The categories are not mutually exclu¬ 
sive, Drought, for example, might belong to 
both. 


101 



owners seeking damages or injunctive 
relief on account of floods allegedly 
caused by weather modification ac¬ 
tivities. In two of the cases the trial 
court denied relief on the ground that 
no causal connection between the ac¬ 
tivities and the floods had been estab¬ 
lished. The third resulted in a jury 
verdict for the defendant weather 
modifier.* The other three suits 
sought injunctive relief against inter¬ 
ference by the weather modifier with 
the plaintiff’s property rights in 
weather. In one, a suit by resort own¬ 
ers against the City of New York, the 
New York court held that the public 
interest in ending a prevailing drought 
outweighed the resort owners’ interest 
in good weather. In another, the only 
decision against the weather modifi¬ 
ers, a Texas court granted an injunc¬ 
tion against hail suppression activities 
carried on by farmers in favor of 
neighboring ranchers who wanted pre¬ 
cipitation in any form, including hail. 
The last of the suits is still pending in 
Pennsylvania.** 

This handful of cases does not, of 
course, provide a firm basis for pre¬ 
dicting how the law will develop. The 
cases do, however, provide food for 
thought about a number of aspects of 
the problem, not the least of which is 


the preview they afford to the kinds 
of conflicts one can expect if large- 
scale weather modification becomes a 
reality: resort owners against city 
fathers; ranchers needing precipita¬ 
tion of any kind against farmers want¬ 
ing to suppress hail; public utilities 
fearing loss of hydroelectric power 
against homeowners fearing disastrous 
floods because of the creation of de¬ 
structive weather conditions. 

The chief obstacle to recovery for 
damage most likely will be the prob¬ 
lem of proving a causal connection 
between the activity and the damage. 
It should be stressed that legal causal¬ 
ity and scientific causality are two 
markedly different things. It is quite 
possible, as the Texas decision under¬ 
scores, that liability could be imposed 
in circumstances which might not jus¬ 
tify the scientist in finding that a 
causal relationship existed. 

Assuming that the requisite causal 
connection can be established, the 


* The case was based on claimed negli¬ 
gence and the jury verdict could mean 
either that no negligence was found or that 
no causal connection was found between 
the acts complained of and the damage. 

**In addition to these actions there is a 
pending criminal proceeding against weather 
modifiers for violation of a municipal ordi¬ 
nance prohibiting such activities. 


102 


next question is whether the injury is 
legally compensable. This could de¬ 
pend on the applicable rule of liabil¬ 
ity, i.e., whether the actor would be 
liable only in the case of fault, negli¬ 
gence or some more reprehensible 
conduct, or in the absence of fault 
under a rule of strict or absolute lia¬ 
bility. The applicable rule might in 
turn depend on the nature of the ac¬ 
tor; whether he is a private operator, 
government contractor, or the govern¬ 
ment itself. There is not much point 
in speculating at this time as to the 
likelihood of a particular rule of lia¬ 
bility’s being adopted. Suffice it to say 
that if a causal connection could be 
established, imposition of tort liability 
on one theory or another would seem 
likely. 

Where the injury claimed is the re¬ 
duction or raising of the precipitation 
level, a substantially different ques¬ 
tion is involved. The answer will turn 
on whether or not a person is held to 
have a property interest in a particu¬ 
lar kind of weather. It is much too 
early to tell how the law will answer 
the question of who owns the clouds. 
A number of possible theories have 
been advanced based on supposedly 
analogous situations. The right to 
clouds has been compared to the right 


to control airspace over one’s land; 
to the right to acquire wild animals by 
reduction to possession; to rights in 
water courses, or percolating, or dif¬ 
fused surface waters. The pertinence 
of some of these analogies is more ap¬ 
parent than real. Rights to airspace, 
to the extent they are recognized, are 
justified as necessary to protect en¬ 
joyment of the underlying land. The 
relationship between the underlying 
land and particular clouds passing 
overhead, however desperate the need 
for water may be, is quite different. 
The considerations bearing on the 
award of control over clouds are not 
all the same as those supporting the 
rule as to animals. A watercourse con¬ 
notes a stream flowing in a reasonably 
definite channel with distinct parcels 
of land bordering on the stream. In 
the Eastern United States, to the ex¬ 
tent that property rights exist, they 
arise by virtue of the ownership of 
the bordering land, a circumstance not 
present in the case of clouds. And the 
rule of most Western states giving 
rights to surface water to the first to 
appropriate it could lead to chaos if 
applied to water in the atmosphere. 
Problems of percolating waters, i.e., 
all subsurface waters other than those 
in underground streams, are most 


103 



nearly analogous. But, here again 
rights, to the extent they exist, are 
based on ownership of the surface 
lartd. This does not mean that there 
are not valuable lessons to be learned 
from the development of water law. 
The adjustment of competing inter¬ 
ests, and the handling—especially in 
the Western States—of the problem 
of scarcity of vital natural asset give 
valuable insights. When all is said and 
done, however, the problems of 
weather and climate modification are 
infinitely more pervasive and complex 
than those of water and should be 
decided on their own merits rather 
than on the basis of wholly or partly 
inapt analogies. 

The two cases which have posed 
the question of “property rights in 
weather” have reached different re¬ 
sults, at least on the surface. In New 
York, the court, while impliedly con¬ 
ceding some interest of the resort 
owners in “good weather,” felt that 
their interest was outweighed by the 
interest of the community in ending 
a drought. The Texas case, on the 
other hand, held that the complaining 
ranch owners had a “natural right to 
such precipitation (from clouds over 
their land) as nature chooses to be¬ 
stow.” Carried to its logical conclu¬ 


sion this decision would make possible 
the barring of any weather modifica¬ 
tion activities except over one’s own 
land. It should be emphasized that the 
relief sought in these cases was in¬ 
junctive, and that conceivably one or 
both cases might have come out dif¬ 
ferently if, instead, damages had been 
sought. That courts would be natur¬ 
ally reluctant to enjoin a municipal¬ 
ity’s efforts to end a drought because 
a resort owner’s good weather was 
threatened does not mean that in an 
appropriate case they would not re¬ 
quire the community to recompense 
the resort owner.* The “natural rights” 
theory of the Texas decision, while a 
sufficient basis for enjoying any inter¬ 
ference, does not offer much hope for 
an award of damages in the light of 
nature’s well-known unreliability. If, 
on the other hand, one measures the 
Texas decision by the New York test 
of balancing the interests of the par¬ 
ties concerned, it may represent a not 
so unreasonable vote for the status 
quo as between the competing claims 
of ranchers and farmers. 

Interesting as these isolated decis- 

* In the actual case, the court found that 
the experiments by the city would not in¬ 
terfere with the resort owners’ business to 
an appreciable extent. 


104 



ions may be, one cannot begin to dis¬ 
cuss rights in weather meaningfully 
until the capability for control be¬ 
comes clearer. If weather modifica¬ 
tions of significance become scientifi¬ 
cally feasible, the implications to 
society and law will be such as to 
require a rethinking of many legal 
concepts. Legislation far broader than 
that suggested below will be needed 
to order relationships between the 
various interests, private and govern¬ 
mental, in the light of the new capa¬ 
bility. In short, it is premature to make 
recommendations about the rules of 
law governing “property rights in 
weather” or the liabilities of weather 
modifiers for damages found to have 
been legally caused by their activities. 

It is not, however, premature to 
make recommendations about one as¬ 
pect of tort liability. This is with 
respect to indemnification of persons 
engaged in weather modification re¬ 
search activities on behalf of the gov¬ 
ernment.* A strong argument can be 
made that persons who carry on gov¬ 
ernment-sponsored research activities 
should be protected against liability 
claims; and that members of the 
public who are injured as a result of 
such activities should receive ade¬ 
quate compensation. In most respects 


the problem is not materially different 
from the case of other hazardous gov¬ 
ernment activities. The nature of that 
problem and the possible solutions 
have been much discussed in recent 
years and will be touched on only 
briefly. 

The most recent study of indemnifi¬ 
cation was conducted by the Legisla¬ 
tive Drafting Fund of Columbia 
University for the National Security 
Industrial Association, under the di¬ 
rection of Professor Albert J. Rosen¬ 
thal of the Columbia University 
School of Law. In the report, Cata¬ 
strophic Accidents in Government 
Programs, the authors, although pri¬ 
marily concerned with Defense De¬ 
partment and NASA activities, pay at 
least passing attention to weather 
modification programs. The recom¬ 
mendations of the report can be taken 
as the starting point for consideration 
of the problem. 

Traditionally, the problem has been 


* The problem of tort liability of private 
operators may be important insofar as they 
are concerned and, indeed, may be impor¬ 
tant to members of the public to the extent 
that there is uncompensated damage for 
particular activities. At the moment, how¬ 
ever, there does not seem to be any justifi¬ 
cation for a government program to handle 
liability on account of private operations. 


105 



viewed as one of indemnifying gov¬ 
ernment contractors against liability 
for damage caused the public, al¬ 
though of late it is being seen increas¬ 
ingly as one of protecting the public. 
However viewed, it is widely agreed 
that the problem requires legislative 
solution. Specific legislation has been 
enacted empowering a number of gov¬ 
ernment agencies to indemnify con¬ 
tractors against liability. Except for 
the Price-Anderson Amendment to the 
Atomic Energy Act, no satisfactory 
legislation to deal with potentially 
castastrophic liability has been en¬ 
acted. 

Quite apart from the question of 
protection of the public and fairness 
to the contractor is the question of 
government self-interest in having re¬ 
search performed. In this respect there 
are already some intimations that the 
problem of liability may have an in¬ 
hibiting effect on research.* 

Unless frustrated in administration, 
an indemnification statute could pro¬ 
vide a satisfactory answer to the prob¬ 
lems of contractors.** From the point 
of view of the public the protection 
afforded is indirect. While government 
indemnity ensures payment of a judg¬ 
ment once secured, up to the limit 
of any ceiling on liability which may 


be imposed, it does not affect the right 
of a member of the public to a judg¬ 
ment in the first instance. 

Whether the government should go 
beyond mere indemnification and 
more directly ensure public protec¬ 
tion, for example, by enacting a law of 
strict liability for contractual activ¬ 
ities, is a subject now being debated 
in the Defense Department and NASA. 
In extending the Atomic Energy In¬ 
demnification legislation the Joint 
Committee on Atomic Energy specifi¬ 
cally called attention to the need for 
inquiry into that problem. Not much 
point is seen in adding to that discus¬ 
sion. As a general rule a member of 
the public injured as a result of gov¬ 
ernment-supported weather modifica¬ 
tion research should be treated the 
same as one injured by DOD or NASA 
activities. It is to be hoped that indem¬ 
nification legislation covering those 
agencies and others will soon be en- 

* “Introduction to Weather Modification: 
Law, Controls, Operations,” H. J. Tauben- 
feld, et al, to be published by the National 
Science Foundation in January 1966. See the 
Appendix. 

** We have discussed the problem in 
terms of contractors. It is conceivable that 
similar problems would be met in the case 
of grantees, and there is no theoretical reason 
why they too should not be covered where 
appropriate. 


106 



acted. Weather modification activities 
should be covered. It is more impor¬ 
tant that some protection be afforded 
than that equality of treatment be pre¬ 
served. If no general legislation is en¬ 
acted, special indemnification legisla¬ 
tion for weather modification should 
be. Needless to say, this recommenda¬ 
tion should not be construed as imply¬ 
ing that any causal connection between 
particular weather modification activ¬ 
ities and injuries to property has been 
established. As noted above, legal 
cause may be found whatever the 
opinions of scientists, and it is the 
risk of liability rather than the scien¬ 
tific reality which is important here. 

The second area of involvement of 
weather modification with the law is 
that of regulation. Considering the 
small amount of activity in the field, 
the amount of State legislation is 
rather staggering. Twenty-two States 
now have statutes dealing with at 
least some aspects of weather modi¬ 
fication and others have legislation 
under consideration. Most of the 
statutes date from the period of the 
early and middle 1950’s, but a few 
have been enacted in the last five 
years. 

In general, State statutes can be di¬ 
vided into two broad classes: 1) those 


the primary aim of which would seem 
to be active control of weather modifi¬ 
cation activities with the collection 
and evaluation of scientific informa¬ 
tion as an important adjunct of con¬ 
trol; and 2) those which aim primarily 
at the collection and evaluation of 
information. In the first and larger 
group restrictive laws necessitate a 
license or registration for operation. 
Where a license is required, it usually 
can be obtained only after a state¬ 
ment is filed showing the qualifica¬ 
tions of the operator, his financial 
responsibility, the nature of the pro¬ 
posed work and the payment of a fee. 
Only two of the States list specific 
criteria of competence. In one case 
the operator must be a professional 
engineer. In the other the operator 
must be a member of, or qualified for 
membership in, the American Meteor¬ 
ological Society. The methods of as¬ 
suring financial responsibility differ 
widely as well. Public notice is often 
required before activities can be un¬ 
dertaken. As a general rule qualifica¬ 
tions, financial responsibility, etc. are 
evaluated by boards and commissions. 
At least eight States have special 
weather control boards, presumably 
with special expertise in the field. 
Most States require reports after the 


107 



conduct of the weather modification 
activity. 

Several States assert sovereign 
rights to the moisture in the clouds or 
atmosphere above their land mass. 
New Mexico, Louisiana and Colorado 
limit weather activities which may 
affect other States, although in the 
case of the latter two, only on a re¬ 
ciprocal basis. One State, Maryland, 
has now barred all weather modifica¬ 
tion activities for a two-year period. 
The Pennsylvania legislature recently 
adopted a bill to prohibit all weather 
modification activities except research 
by universities and the State and Fed¬ 
eral governments. The bill was vetoed 
by the Governor. 

To gauge the operation and adminis¬ 
tration of these statutes, the Commis¬ 
sion sent questionnaires to all States 
and all known commercial operators 
and researchers active in the field. The 
answers to those questionnaires, 
which are analyzed and summarized 
in the report referred to above entitled 
“Weather Modification: Law, Con¬ 
trols, Operations,’* would indicate that 
the effect of regulatory legislation on 
weather modification has been slight. 
To be sure, there were instances of 
dissatisfaction, but little evidence that 
existing laws have caused any sub¬ 


stantial dislocation to operators. It is 
interesting to note that, nevertheless, 
there was a widespread agreement 
that Federal legislation would be wel¬ 
come. 

For present purposes, the signifi¬ 
cance of State regulatory legislation 
is not so much its past effect but its 
potential impact on programs which 
may be desirable. Obviously, any leg¬ 
islation which prohibits weather mod¬ 
ification activities—if construed to 
apply to research as well as commer¬ 
cial activities—could have a serious 
effect on desirable programs. State 
licensing requirements in some circum¬ 
stances could place a serious burden 
on any experiment crossing State lines, 
and most experiments of any size 
would be likely to do so. The nature 
of the subject, including the likelihood 
that the effects of activities will not 
be restricted to a single State make it 
seem probable that Federal regulatory 
legislation will ultimately be needed. 
The question of immediate interests is 
whether anything needs to be done 
now. 

At the present time, the only Federal 
“regulation” of weather modification 
activities is the report form required 
to be filed annually by all operators 
of whose activities the National Sci- 


108 



ence Foundation has become aware. 
The report is required pursuant to 
the authority of the Foundation under 
PL 85-510, “to obtain by regulation, 
subpoena, or otherwise, such informa¬ 
tion ... as may be deemed necessary 
or appropriate ... to carry out . . . 
the program of study, research and 
evaluation in the field of weather 
modification.” This after the fact sys¬ 
tem of information collection has re¬ 
cently been changed. Effective January 
1, 1966, the Foundation adopted a new 
regulation requiring that all weather 
modifiers keep certain records, and, 
in addition, give the Foundation thirty 
days* advance notice of any proposed 
activity. The purpose of the record¬ 
keeping requirements is, in the words 
of the Regulation, “to develop infor¬ 
mation for use in carrying out the 
responsibility of the National Science 
Foundation to support a program of 
study, research, and evaluation in the 
field of weather modification . . .” 

It is too early to tell how the new 
regulation will work, and whether its 
objective will be accomplished. While 
it is conceivable that no additional 
action will be necessary, it seems 
likely that even for the immediate 
future further steps will be necessary. 
Fulfillment of the objectives of the 


program recommended in this report 
requires that research have a very 
high priority. This means that State 
and local legal rules cannot be per¬ 
mitted to interfere with research ob¬ 
jectives. Interference can be of two 
kinds. First, the local rules may im¬ 
pose liability for injuries caused by 
research projects; the threat of liabil¬ 
ity may act as a deterrent to research¬ 
ers. For the reasons set forth above, 
it is not believed that the time is ripe 
for postulating new rules of liability. 
Consequently, the best way of dealing 
with the possibility of this kind of 
interference is by indemnity or other 
protection against liability. 

There remains, however, the possi¬ 
bility of direct interference by injunc¬ 
tion, either pursuant to a statute or 
ordinance forbidding or restricting 
weather modification activities, or as 
in the Texas case under the courts’ 
general power to prevent interfer¬ 
ences with property rights. It is worth 
noting that where timing is important, 
even a temporary injunction can have 
disastrous effects on a research proj¬ 
ect. So long as the work is carried on 
directly by the Federal government it 
would seem to be immune to injunc¬ 
tion. If it were carried on by a govern¬ 
ment contractor, whether a private 


109 



company or an institution, the immun¬ 
ity would be much less clear. And, 
where research is carried on pursuant 
to grant, there would appear to be no 
governmental immunity whatsoever. 
Provision should be made to ensure 
that all properly conducted experi¬ 
ments including those conducted by 
contract or grant should be immune 
to local interference. 

A somewhat different problem is 
posed by the possibility that some 
weather modification activities may 
physically interfere with government 
activities. As pointed out elsewhere 
in the report, the nature of cloud- 
seeding experiments is such that there 
is a real possibility of contamination 
by other seeding operations in the 
same general location. Such contami¬ 
nation can be expensive and scien¬ 
tifically catastrophic in view of the 
limited opportunities available for 
some kinds of research. A part of the 
problem can probably be taken care of 
by the proposed Foundation regula¬ 
tions requiring advance notice of all 
operations. But advance notice may 
not be enough; in some cases it may 
be desirable to stop the interfering 
weather modification activity. If those 
activities are carried on by other re¬ 
searchers, whether or not Federally 


supported, persuasion will probably 
be sufficient. Where commercial oper¬ 
ators are involved persuasion may be 
less effective. In either event, power 
to halt interference should be avail¬ 
able where necessary to protect the 
integrity of government operations. 
The power does not exist today. The 
power to halt interference and the im¬ 
munity from state interference need 
not be unlimited. Room can be left for 
reasonable accommodation of the 
needs of local governments. But, pri¬ 
ority of the Federal program must be 
established. 

One other suggestion for regulation 
—that private operators be required 
to evaluate their operations—should 
be discussed. Because of the nature 
of research in weather modification, 
and the nature of the problem of eval¬ 
uating results, it would be particularly 
desirable to use all experiences in¬ 
cluding those of private operators. If 
full advantage is to be taken of their 
experiences, they should be carried on 
and evaluated in accordance with pre¬ 
scribed methods of project design, 
analysis, etc. Where government con¬ 
tractors or grantees are involved this 
should not pose any great difficulty. 
The case is different with private 
operators where, among other objec- 


110 



tions, the increased cost of operation 
might be prohibitive. For the moment 
it is felt that no such requirements 
should be imposed on private opera¬ 
tors, but the situation may change 
rapidly. In the meantime, study should 
be given to the legal obstacles, if any, 
to such a requirement, and the desira¬ 
bility or necessity of government 
financing of the evaluation. 

Thus the Commission recommends 
that the Federal Government by ap¬ 
propriate legislation be empowered to: 

1) delay or halt all activities—pub¬ 
lic or private—in actual or potential 
conflict with weather and climate 
modification programs of the Federal 
government, whether carried on by the 
government itself or by its grantees 
or contractors; 

2 ) immunize Federal agents, gran¬ 
tees, and contractors engaged in 
weather and climate modification ac¬ 
tivities from State and local govern¬ 
ment interference; and 

3) provide to Federal grantees and 
contractors indemnification or other 
protection against liability to the pub¬ 
lic for damages caused by Federal 
programs of weather and climate 
modification. 


In view of the state of the art, it 
would seem appropriate to limit regu¬ 
lation to the least amount consistent 
with achievement of the objectives of 
the program. The Commission’s recom¬ 
mendations are deliberately restricted 
in scope. It would be well to note, 
however, that as the art develops, and 
as weather and climate modification 
activities increase, comprehensive reg¬ 
ulation seems inevitable. Such regula¬ 
tion will probably require the setting 
of minimum standards of competence, 
and perhaps financial responsibility, 
for all operators and the establishing 
of some authority for deciding be¬ 
tween competing claims for priority. 
What the proper amount of regulation 
is will depend on how rapidly the field 
expands. It may be that the findings 
of the NAS Panel will stimulate very 
rapid expansion of field programs. The 
regulatory program may well have to 
keep pace. 

Whatever regulation is decided 
upon must be national in scope. While 
it may be that some activities will 
have effects limited to the boundaries 
of a particular State, it seems likely 
that such cases will be exceptional. 
Whether there will be any need for or 
utility in simultaneous regulation by 
the States will depend on the nature 


111 



of the Federal program and the devel¬ 
opment of the technology. It may be 
that regulation at the national level 
will be sufficient, or indeed, that ex¬ 
clusive Federal control is demanded. 
Such questions can be left for the 
future. For now it would not appear 
necessary to intrude on state pro¬ 
grams, provided only that they do not 
have the effect of impairing the Fed¬ 
eral effort. 


Domestic regulation, whether 
wholly national or mixed national and 
state, should not be regarded as all 
that is necessary. Global phenomena 
are involved in the weather and effec¬ 
tive regulation must ultimately be 
global in character. It is to be hoped 
that as the needs of an adequate regu¬ 
latory system become defined, efforts 
will be made to establish the system 
on an international basis. 


With respect to the weather modification prohibi¬ 
tion bill recently vetoed by the Governor of Penn¬ 
sylvania and referred to on page 108 this chapter , 
subsequently on November 9, 1965 the Governor 
signed into law Act No. 331 granting to each of 
the counties the optional authority to prohibit any 
weather modification activities deemed detrimen¬ 
tal to a county’s welfare. 


112 



WEMIEI 

MOUHtUIH 

HD 

HEMHnmi 

ibihoib 


The major impulse behind the de¬ 
velopment of a national program of 
weather modification arises in asso¬ 
ciation with problems encountered 
within the United States. Efforts to 
develop or apply weather modification 
techniques on the part of governmen¬ 
tal agencies, research institutions and 
commercial enterprises have focused 
mainly on domestic problems and 
have been carried out primarily within 
the borders of this country or over the 
open seas. It might seem, therefore, 
that weather modification had little to 
do with international relations or con¬ 
siderations of foreign policy. This 
would, however, be an erroneous view. 
The active interest in the subject dis¬ 
played in foreign countries and in in¬ 
ternational organizations, the interna¬ 
tional impact of projected research 
and operational programs and the con¬ 
tribution which a weather modification 
program could make to the foreign 
policy objectives of the United States 
are indicative of the international im¬ 
plications of this area of scientific 
effort. 

The evidence before us suggests 
that attempts to augment rainfall over 
areas of a few thousand square miles 
may have effects that may extend 
many miles downstream from the site 


at which the seeding agent is intro¬ 
duced into the atmosphere—clearly 
far enough in some instances to cross 
national boundaries. The probability 
of success in such activities is now 
sufficiently high to warrant immediate 
attention to their implications for in¬ 
ternational relations. The possibility 
of downstream diminution of rainfall 
—though small—cannot be completely 
ignored, with even greater implica¬ 
tions for international problems in 
equitably sharing a natural resource. 
If the political problems are suffi¬ 
ciently near at hand to suggest Fed¬ 
eral, rather than State, regulation 
domestically (see the chapter in this 
report on Legal and Legislative As¬ 
pects), it is not too early to give some 
attention to the international political 
problems and opportunities. 

Rudimentary attempts have already 


As a basis for the preparation of this 
chapter of the report, members of the Com¬ 
mission, in addition to reviewing the limited 
literature bearing upon the subject, con¬ 
sulted with a number of government offi¬ 
cials and persons in private life experienced 
in international affairs and particularly in¬ 
ternational scientific programs. The Com¬ 
mission also obtained a report on interna¬ 
tional relations and weather modification 
from Leonard E. Schwartz of Operations 
and Policy Research, Inc. of Washington, 
D. C. See the Appendix. 


113 



been made to influence the intensity of 
hurricanes over international waters. 
Although no success has been claimed, 
the probability of success in future 
attempts is somewhat greater than 
zero. A similarly small probability of 
success will be applicable to attempts 
to influence the direction of move¬ 
ment of a hurricane when those at¬ 
tempts are made. Not much imagina¬ 
tion is required to envision the kind 
of international political problems that 
might ensue should those small prob¬ 
abilities of success be realized. 

Even graver problems, though much 
more remote, arise in the matter of 
possible modification of the climate 
over areas of subcontinent size. The 
fundamental unity of the global atmos¬ 
phere and the close coupling and in¬ 
teraction that exist among the major 
components of planetary wave are 
well recognized characteristics of the 
atmosphere. The situation in which a 
drought of many months duration in 
one section of the United States occurs 
concomitantly with above normal rain¬ 
fall in another section can be general¬ 
ized. If one day it turns out to be 
possible to exercise meaningful modi¬ 
fication of the weather or climate over 
one region of the earth’s surface it is 
quite possible that a compensating 


alteration will take place in the atmos¬ 
phere over some other region. 

There is the very long-range matter 
of influencing the world-wide climate 
either by conscious intervention 
through exploitation of triggering 
effects or inadvertently as the multi¬ 
farious activities of an expanding 
population exert an ever more pro¬ 
found influence on man’s natural en¬ 
vironment. In the latter case, issues 
arise that transcend national consid¬ 
erations and affect all mankind. 

The salient points can be summarized: 

1. For each identifiable class of 
meaningful modification of weather 
or climate (e.g., dissipation of super¬ 
cooled fog, augmentation or redistri¬ 
bution of rainfall, suppression of hail, 
altering the intensity or causes of hur¬ 
ricanes, large-scale modification of cli¬ 
mate), there exists a probability of 
success. The probabilities range from 
very high for supercooled fog through 
something greater than 50 percent for 
rainfall, down to very low but greater 
than zero for large-scale climate 
effects. 

2. The implications for international 
relations of success in each class of 
weather and climate modification de¬ 
pend on the particular class in ques- 


114 



tion. For example, the implications are 
minor in the case of supercooled fog, 
quite significant for rainfall, large for 
hurricanes, and very large indeed for 
world climate. 

3. In contrast to the situation exist¬ 
ing a decade or so ago, now at hand 
are the scientific and technological 
tools to explore the limitations and 
practical applications of each class of 
activity. 

INTERNATIONAL MUMS 
RELATED TO WHINER 
MODIFICATION 

International cooperation in the 
study of the earth’s atmosphere has 
been carried on for many years 
through both governmental and pri¬ 
vate agencies. Official international 
activities in this field have been cen¬ 
tered in the World Meteorological 
Organization (WMO) established in 
1947 primarily in connection with the 
collection of weather data for fore¬ 
casting purposes. In the non-govern¬ 
mental area, the International Council 
of Scientific Unions (ICSU) and its 
constitutent bodies have played a cen¬ 


tral role. Such large world-wide pro¬ 
grams of scientific research as the 
International Geophysical Year (IGY) 
and the International Years of the 
Quiet Sun (IQSY) have not only wid¬ 
ened man’s knowledge of the factors 
bearing upon the atmosphere and con¬ 
sequently weather and climate, but 
have also demonstrated new and 
imaginative patterns of international 
cooperation. 

The United States Government has 
for some years participated in bilateral 
cooperation with other governments 
in the field of meteorology with em¬ 
phasis upon weather forecasting. The 
agreement with the Soviet Union an¬ 
nounced in October 1964 for the ex¬ 
change of meteorological satellite data 
between Moscow and Washington 
over a special twenty-four hour com¬ 
munications link is one of the most 
recent and interesting examples of this 
bilateral cooperation. An example of 
bilateral cooperation having world¬ 
wide ramifications is the TIROS 
weather satellite program developed 
by the U. S. Weather Bureau and the 
National Aeronautics and Space Ad¬ 
ministration. Under this program the 
United States is now making available 
valuable meteorological data collected 
by a TIROS satellite and immediately 


115 



transmitted to receiving stations in 
foreign countries over a specially de¬ 
vised communications system. 

Multilateral international activities 
more directly related to the problems 
of weather modification were stimu¬ 
lated by President Kennedy’s speech 
to the General Assembly of the United 
Nations in September 1961, in which 
he appealed for international coopera¬ 
tion in the peaceful uses of outer 
space. The Assembly responded by 
adopting Resolution 1721 (XVI) in 
December of that year, Part C of which 
contained recommendations for ad¬ 
vancing the state of the atmospheric 
sciences with a view to determining 
the possibility of large-scale weather 
modification and for developing an 
improved system of weather forecast¬ 
ing. The principal responsibility for 
carrying out the necessary studies and 
planning with respect to weather fore¬ 
casting was placed upon the WMO, 
while ICSU was subsequently invited 
to formulate additional suggestions 
for advancing research in the atmos¬ 
pheric sciences. The development of 
the improved world weather system 
(subsequently named the World 
Weather Watch) through the WMO 
and of the basic research program 


through the ICSU are closely related, 
in that the projected system of data 
collection and processing will serve 
the purposes of both. 

Weather modification is thus inti¬ 
mately related to the broader program 
of international collaboration in the 
atmospheric sciences which has 
emerged during the last three or four 
years and which consists of the fol¬ 
lowing four main elements: 

1. The program of atmospheric re¬ 
search now being planned in the World 
Meteorological Organization and the 
Inter-Union Committee on Atmos¬ 
pheric Sciences of ICSU; 

2. The World Weather Watch being 
developed through the World Meteor¬ 
ological Organization; 

3. A climatological program aimed 
at an improvement in the description 
of world-wide climate with a view to 
facilitating the better utilization of 
land and water resources and ulti¬ 
mately contributing to the objective 
of modifying climatic conditions. 

4. Strengthened educational pro¬ 
grams to provide the scientific and 
technical manpower required for the 
overall program. 

The scientific community of the 
United States has played a major role 


116 



in the formulation of this program and 
is continuing to do so. Moreover, the 
U. S. Weather Bureau has had a prom¬ 
inent part in the development of plans 
for the World Weather Watch and the 
program of atmospheric science re¬ 
search being developed by the WMO. 
The interchange of ideas and the close 
collaboration that has been effected 
between scientists in the government 
and in private institutions—and be¬ 
tween those primarily engaged in re¬ 
search and those occupied in govern¬ 
mental weather services—have proved 
important in reflecting the views of a 
broad cross-section of the scientific 
community and in assuring that the 
requirements of both research and 
operations receive proper and ade¬ 
quate attention. It is hoped this com¬ 
plementary relationship will continue 
not only on a national but also on an 
international level. 

WTEMUHOIUL REQUIREMENTS 
OF RESEARCH 

The broad program of research out¬ 
lined in earlier chapters of the Com¬ 
mission’s report demonstrates the need 
for approaching problems of weather 


and climate modification with a strong 
emphasis upon international coopera¬ 
tion. To be sure, much of the research 
to be undertaken will be carried out 
within the borders of the United 
States. Nevertheless, the extensive and 
significant work that is being done in 
other countries underscores the need 
for promoting the international ex¬ 
change of data and research findings 
for the purpose of maximizing their 
usefulness. The need for international 
collaboration in the actual planning 
and conduct of research activities may 
be expected to increase as research 
moves out of the laboratory and into 
the realm of field experiments asso¬ 
ciated with the study of the dynamics 
of climate, the establishment of a 
global weather observation network 
(which supports the numerical simu¬ 
lation program) and the investigation 
of other aspects of the general atmos¬ 
pheric circulation. Proposals for re¬ 
search already advanced, such as those 
involved in the World Weather Watch, 
involve a reliance upon widespread 
international collaboration in data col¬ 
lection. They require the selection of 
areas of study far removed from the 
United States, such as land and sea 
areas in the southern hemisphere and 
the polar regions. Both the basic 


117 



knowledge gained in such investiga¬ 
tions, and its practical application to 
weather forecasting and weather and 
climatic modification, will be of great 
interest to many countries. The tech¬ 
nological and human resources re¬ 
quired for the conduct of this type of 
research are far beyond the capability 
of most countries to provide individ¬ 
ually. Increased international collabo¬ 
ration in such endeavors would seem, 
therefore, to be inevitable. 

Looking into the future to the time 
when field experiments with weather 
or climate modification are expanded 
in scope and number and involve ac¬ 
tual attempts to introduce changes in 
the atmosphere, some form of inter¬ 
national collaboration will be essential 
in the planning and execution of proj¬ 
ects that may have an impact not only 
upon the immediate localities but on 
areas in other countries and even upon 
other continents distant from the scene 
of work. It is possible situations of 
this sort may arise in the near future 
if an expanded program of field ex¬ 
periments in cloud seeding is under¬ 
taken in areas near the northern or 
southern borders of the United States. 
An expansion in experimentation with 
tropical hurricanes may also present 


international complications heretofore 
avoided. 

WEATHER MODIFICATION AND 
WORLD POLITICS 

In the present stage of world affairs 
any scientific advance contributing 
significantly to man's ability to affect 
the natural environment has a bearing 
upon the political relations among 
states and the quest for peace and 
security. The importance to military 
operations of a capability for modify¬ 
ing local weather conditions is obvious. 
Moreover, in view of its potentially 
spectacular character and its impor¬ 
tant consequences for the welfare of 
all nations, a capability for significant 
weather modification would augment 
the prestige and political influence of 
the country which first achieved it. 

Nor can it be overlooked that an 
ability to control weather conditions 
could have an effect upon international 
conflicts apart from the range of 
strictly military operations. The effec¬ 
tive precipitation of water from mois¬ 
ture-laden clouds over the territory of 
one State to the real or imagined detri- 


118 



ment of an adjoining State normally 
dependent upon the same sources of 
atmospheric moisture, could easily 
serve to stir up international contro¬ 
versies and exacerbate existing ten¬ 
sions. Even the remote possibility that 
a nation might develop a capability of 
using weather modification measures 
to damage the economy and civil 
population of another country must 
be recognized. 

RELATION TO O.S. FOREION POLICY 

It should be clear that a long-range 
program of weather and climate modi¬ 
fication can have a direct bearing upon 
the main purposes of American foreign 
policy. It can contribute to defending 
the security of the United States and 
other nations of the free world. It can 
aid the economic and social advance¬ 
ment of the developing countries, 
many of which face problems asso¬ 
ciated with adverse climatic condi¬ 
tions and serious imbalances in soil 
and water resources. It can serve as 
a new and widening area for the de¬ 
velopment of common interests with 
both friends and present adversaries, 
and thus stimulate new patterns of 
international cooperation. 


The challenge and the opportunity 
presented to the world community by 
the prospect of man's achieving the 
ability to modify the atmospheric en¬ 
vironment form one of the most excit¬ 
ing long-range aspects of the subject. 
It involves the possible acquisition of 
a new and enormous power to influ¬ 
ence the conditions of human life. The 
potentialities for beneficial application 
are vast, as are also the potential dan¬ 
gers. It is in the long run essential to 
develop political and social controls 
over the use of this power which will 
maximize the opportunities for its con¬ 
structive, peaceful use and minimize 
the factors which tend to involve it in 
the tensions and conflicts inherent in 
human society. 

The very fact that the development 
of a capability for influencing the at¬ 
mospheric environment is still in its 
infancy should widen the opportunity 
presented by this scientific endeavor 
to develop attitudes and patterns of 
collaboration which can contribute 
not only to the achievement of the 
practical technological goals, but also 
to the relaxation of international ten¬ 
sions. Vested national interests in 
technological achievement in weather 
modification are still limited. In con¬ 
trast to the field of atomic energy and 


119 



developments in outer space, no nation 
has yet forged a weapons system in 
the field of weather or climate control 
that can threaten the security of an¬ 
other country. Moreover, while politi¬ 
cal influences have by no means been 
totally absent in even the restricted 
international programs that have so 
far been initiated in the atmospheric 
sciences, no major political issues 
have yet been raised on which rigid 
and irreconcilable positions have been 
taken. Small beginnings in collabora¬ 
tion on problems of weather and cli¬ 
mate have already been made which 
could prove useful in helping to build 
the habit of cooperation and in stimu¬ 
lating a pragmatic recognition of the 
material advantages to be derived from 
that approach. 

INTERMTIOIIIIL IMPACT OF 
O.S. PROGRAM 

The growing recognition of the effi¬ 
cacy of certain cloud-seeding practices, 
coupled with an increased public de¬ 
mand for rain-making operations stim¬ 


ulated by a series of dry years in the 
United States, will no doubt produce 
a greatly enlarged interest and activity 
in connection with weather modifica¬ 
tion. Field experiments conducted both 
by governmental and private agencies 
may be expected to expand. Commer¬ 
cial operations may well increase. 
Larger public appropriations for 
weather and climate modification pur¬ 
poses will be sought and probably 
made. Legislation dealing with various 
aspects of weather and climate modi¬ 
fication will be considered and prob¬ 
ably be enacted. 

An expanded United States activity 
in weather and climate modification 
cannot fail to have its impact upon 
governments and public opinion in 
other countries. Questions will arise 
as to the exact level of capability 
achieved by the United States in affect¬ 
ing weather; the potential benefit or 
danger which this power to influence 
the atmosphere may imply for other 
countries; and the policies and pur¬ 
poses that will guide the United States 
in the development and exercise of 
this new technology. 


120 



ORGANIZATION OF 
INTER-BOVEIINMENTAL 
COOPERATION 

The responsibility for promoting 
inter-governmental cooperation and 
contacts on the scientific and techni¬ 
cal level with respect to weather and 
climate modification be recognized in 
whatever administrative arrangements 
are decided upon for the national pro¬ 
gram in this field. The close relation¬ 
ship of weather modification to other 
programs and responsibilities of the 
government would, of course, require 
an adequate system of inter-agency 
coordination in connection with 
United States participation in interna¬ 
tional weather and climate modifica¬ 
tion activities. 

The formal adoption of a policy of 
international cooperation for the 
peaceful development of weather and 
climate modification would confirm 
and support the limited but significant 
cooperation now being extended by 
governmental and private agencies of 
the United States in this field. It should 
provide an impetus for further activ¬ 


ities of this sort by the various inter¬ 
ested agencies and organizations 
through both bilateral and multilateral 
channels of contact with foreign coun¬ 
tries. The policy decision should also 
lay the basis for the planning of future 
programs and the anticipation and 
study of problems associated with the 
international aspects of modification 
activities. 

The Commission endorses support 
by the United States of the World 
Weather Watch and the program of 
research in atmospheric science being 
planned by the WMO and ICSU. As 
a further measure of international co¬ 
operation, the Commission urges that 
if a national laboratory is established, 
it be given a mandate to promote the 
wide participation of foreign govern¬ 
mental and private institutions in the 
development of research programs of 
international interest. The successful 
execution of this function by a United 
States national institution might pave 
the way for the future establishment 
on a truly international basis of one 
or more centers devoted to the co¬ 
operative study of the atmosphere and 
its intervention in the interests of hu¬ 
man welfare. 


121 



SCIENTIFIC UNO TECHNICAL 
EXCHANGE 

In the basic field of international 
exchange of information and technical 
cooperation several problems present 
themselves. A major limitation affect¬ 
ing both advanced and developing 
countries is the shortage of trained 
personnel in atmospheric sciences at 
all levels. The growing discrepancy 
between the advanced and developing 
countries in this respect imposes a 
further obstacle to genuine interna¬ 
tional cooperation. Attention should 
be given to the question of how greater 
emphasis can be given to atmospheric 
sciences in existing bilateral and mul¬ 
tilateral programs of education and 
technical cooperation, and to what 
additional measures may be needed 
to fill any deficiency. 

Encouragement should also be given 
to the development of basic research 
on the impact of weather modification 
measures in foreign countries. Other 
chapters of this report have indicated 
the need for greater attention to the 
biological and economic and social 
aspects of weather modification in the 
United States. A different set of prob¬ 


lems may well be encountered in many 
of the less developed countries where 
the natural environment and patterns 
of economic and social life present 
contrasts to those prevailing in this 
country. A greater understanding of 
the significance of these differences 
must precede any attempt to evaluate 
the suitability of various weather 
modification practices for specific for¬ 
eign areas and to design appropriate 
programs of cooperation. The oppor¬ 
tunity for international cooperation in 
such research programs is obvious. 

WTERIUTIONAL LEGAL PROBLEMS 

Some form of international regula¬ 
tion of weather modification activities 
will no doubt become essential in the 
future as research and operational 
activities increase in number and ex¬ 
tent. One forum for the international 
consideration of legal aspects of this 
problem, insofar as they concern ac¬ 
tivities in outer space, already exists 
in the legal subcommittee of the Com¬ 
mittee on Peaceful Uses of Outer Space 
of the United Nations General Assem- 
I bly. Little attention has yet been given, 


122 



however, to such basic questions as 
the proprietary rights of states to the 
atmosphere passing over their terri¬ 
tories; the liabilities of states for 
damage inflicted upon the adjoining 
states as a result of deliberate or in¬ 
advertent tampering with the atmos¬ 
phere; or procedures for advance 
notification or consultation regarding 
projected weather modification meas¬ 
ures capable of affecting other states; 
etc. If international regulations are 
formulated, the whole question of en¬ 
forcement likewise comes to the fore. 

QUESTIONS OF INTEIUUTIOIIilL 
ORGANIZATION 

Looking even farther ahead, thought 
must be given to the types of interna¬ 
tional organization that will be needed, 
and the functions they should per¬ 
form, if and when operations in 
weather and climate modification af¬ 
fecting large continental areas become 
feasible. At present international or¬ 
ganizations in the field of atmospheric 
sciences are of the traditional, general 
membership variety with limited func¬ 
tions of information exchange and 


voluntary coordination of national 
programs. Whether the assignment of 
operational responsibility to an inter¬ 
national agency should be considered 
for the future deserves thought even 
at this early date. What new concepts 
of international organization suggest 
themselves for that purpose and what 
new problems of a technical or politi¬ 
cal nature would be precipitated by 
such a plan? Considerable light may 
be thrown on these questions by the 
experience to be gained in the global 
observation program now being 
planned in connection with the World 
Weather Watch. 

Steps should be taken by the United 
States, in concert with other nations, 
to explore the international institu¬ 
tional mechanisms that may be appro¬ 
priate to foster international coopera¬ 
tion and cope with the problems which 
may be anticipated in the field of 
weather and climate modification. The 
United Nations and its specialized 
agencies (e.g. the World Meteorologi¬ 
cal Organization) is suggested as a 
possible governmental framework. The 
International Council of Scientific 
Unions and its associated unions (e.g. 
the International Agencies of Geodesy 
and Geophysics) could be a suitable 


123 



non-governmental framework for 
these mechanisms. 

Rarely has a more inviting oppor¬ 
tunity been offered for advance think¬ 
ing and planning regarding the impact 
of a technological development upon 
international relations. It is hoped that 
government agencies, universities, re¬ 
search institutes, centers of interna¬ 
tional studies, societies of international 
law, as well as individuals will take 
advantage of this possibility of con¬ 
tributing to the maximum utilization 
of the anticipated capability of affect¬ 
ing weather and climate in the inter¬ 
ests of peaceful world development. 
Progress in the diminution of inter¬ 
national tensions and the achievement 
of peace will come not so much from 
the dramatic resolution of basic inter¬ 
national controversies as from the far 
less spectacular growth in ways of co¬ 
operation and from the widening of 
areas of mutual interest among rival 
nations. 

RECOMMENDED BASIC POLICY 
STATEMENT 

The Commission believes that it 
would be highly desirable for the 


Government of the United States, in 
connection with the expansion of its 
program of weather and climate modi¬ 
fication, to issue a basic statement as 
to how it views the relationship of this 
new national effort to the interests, 
hopes and possible apprehensions of 
the rest of the world. The Commission 
further believes that emphasis upon 
international cooperation in the devel¬ 
opment of weather and climate modi¬ 
fication programs will contribute sub¬ 
stantially to scientific and technical 
progress and will also serve the na¬ 
tional purpose of seeking to build a 
peaceful world order. 

The Commission recommends the 
early enunciation of a national policy 
embodying two main points: 1) that it 
is the purpose of the United States, 
with normal and due regard to its own 
basic interests, to pursue its efforts in 
weather and climate modification for 
peaceful ends and for the constructive 
improvement of conditions of human 
life throughout the world; and 2) that 
the United States, recognizing the 
interests and concerns of other coun¬ 
tries, welcomes and solicits their 
cooperation, directly and through 
international arrangements, for the 
achievement of that objective. This 


124 



cooperation should cover both re¬ 
search and operational programs of 
interest to other countries. It should 
be concerned not only with deliberate 
but also inadvertent human interven¬ 
tions in the atmosphere that affect 


weather and climate. Such a policy 
declaration could be issued by the 
President or incorporated in any basic 
legislation on the subject of weather 
and climate modification which the 
Congress may enact. 


125 



FEDERAL FINANCIAL SUPPORT OF 
WEATHER AND CLIMATE 
MODIFICATION 

present suppon 

The chart set forth below shows 
that with the exception of FY 1962 the 
total Federal government support of 
agency research and development pro¬ 
grams in weather and climate modi¬ 
fication remained at about the same 
level during the first 5 years after the 
initial funding of the National Science 
Foundation program in FY 1959 and 
increased at the rate of 35-40% per 
year in the last 3 fiscal years. 


Federal Funding of Weather Modification Programs 


Mi 11 ions 
of 

Dol lars 



2 


Ol I i i i J _ l _I 

59 60 61 62 63 64 65 66 

FISCAL YEAR 


Source: National Science Foundation 


FUNDING AND 
AUMINISTRA 
HON 

REQUIREMENTS 


126 



The table below displays the last 
fiscal year 1965 and the current fiscal 
year 1966 budgets of each of the seven 
agencies in terms of the six goals for 


weather modification research estab¬ 
lished by the Interdepartmental Com¬ 
mittee for Atmospheric Sciences 
(ICAS). 


FEDERAL WEATHER MODIFICATION PROGRAM 
(millions of dollars) 


Department 
or Agency 

Fog & 
Cloud 
Diss. 

Precip. 

Modif. 

Hail 

Supp. 

Light¬ 

ning 

Modif. 

Severe 

Storm 

Modif. 

Other 

Total 

Agriculture 



FY 1965 

0.14 



0.14 

NSF 

— 

1.55 

— 

0.23 

— 

0.22 

2.00 

Commerce 

_ 

_ 

_ 

_ 

0.10 

0.02 

0.12 

Army 

0.16 

— 

— 

0.09 

— 

— 

0.25 

Navy 

0.71 

— 

— 

— 

0.20 

— 

0.91 

Air Force 

0.25 

— 

— 

— 

— 

— 

0.25 

Interior 

— 

1.26 

_ 

_ 

— 

— 

1.26 

TOTALS 

1.12 

2.81 

— 

0.46 

0.30 

0.24 

4.93 

NSF 

0.03 

1.22 

FY 1966 

0.35 

0.10 

0.10 

0.20 

2.00 

Commerce 

— 

0.035 

0.035 

0.13 

0.32 

0.13 

0.65 

Army 

0.16 

— 

— 

0.09 

— 

— 

0.25 

Navy 

0.71 

— 

— 

— 

0.20 

— 

0.91 

Air Force 

0.26 

— 

— 

— 

— 

— 

0.26 

Interior 

_ 

2.98 

_ 

— 

— 

— 

2.98 

Agriculture 

— 

— 

— 

0.14 

— 

— 

0.14 

TOTALS 

1.16 

4.235 

0.385 

0.46 

0.62 

0.33 

7.19 


127 



These tables indicate that the seven 
agencies reported to ICAS budget 
totals of $4.93 million for FY 1965 and 
$7.19 million for FY 1966 in direct sup¬ 
port of weather modification. 

For purposes of understanding the 
relationship of the current support 
for weather and climate modification 
research to the support for the over¬ 
all scientific research programs and 
services of which it is a part, there 
are set forth below tables displaying 
the FY 1965 and 1966 total Federal 
budget for atmospheric sciences and 
meteorological services. 


Federal Funds for Atmospheric 
Sciences and Meteorological 
Services 

(millions of dollars) 


FY 1965* 

FY 1966 

Aeronomy 

110.7 

111.3 

Meteorology 

98.3 

116.0 

Total Atmospheric 
Sciences* 

209.0 

227.3 

Total Meteorological 
Services** 

261.2 

273.3 

Grand Total 
Atmospheric 
Sciences and 
Meteorological 
Services 

470.2 

500.6 

* Source: Interdepartmental Committee for 


Atmospheric Sciences 
** Source: Office of the Federal Coordinator 
for Meteorological Services and 
Supporting Research 


128 



Need lor increased support 
lor Research, Development, 
and operations 

The Commission recommends that 
the total current FY 1966 budget for 
climate and weather modification re¬ 
search of approximately $7.2 million 
be increased by 1970 to $20 to $30 
million or approximately 5% of the 
total current FY 1966 budget of $500.6 
million for both atmospheric sciences 
and meteorological services. Addi¬ 
tional increases of the same order are 
needed for basic research and for large 
computing facilities, making for a total 
increase of $40 to $50 million per year 
by 1970. 

At present weather and climate 
modification research represents less 
than 2% of the current budget for the 
scientific research programs and serv¬ 
ices of which it is an integral part. 
The foregoing recommendation would 
mean that the total budget for weather 
and climate modification research 


would be maintained at the same rate 
of increase of the last 3 fiscal years, 
namely 35-40 percent per year, in 
order to reach a support level of $20 
to $30 million per year by FY 1970. 1 
Additional amounts will be needed for 
underlying basic research activities 
and the provision of large computing 
facilities. 

This recommendation is in recogni¬ 
tion of the uncertainties in the state of 
knowledge and potentialities in the 
field of weather and climate modifica¬ 
tion and the diversity and magnitude 
of effort required to exploit the possi¬ 
bilities which have been discussed 
elsewhere in this report. Weather and 
climate modification research should 
now have a more important role in 
research and development in the at¬ 
mospheric sciences. Large, scientifi¬ 
cally designed and controlled field 
experiments are needed. Associated 
biological and social science research 
is desirable to measure the effects of 


1 These figures include applied research 
and immediately supporting basic research 
for increasing precipitation by seeding, sup¬ 
pression of lightning and hail, fog and cloud 
dispersal and severe storm modification. 
They do not include the longer range basic 
research studies required for assessment of 
advertent and inadvertent modification of 
climate. 


129 



experiments on the ecological and 
social systems. Required also are 
costly logistics support, aircraft, in¬ 
strumentation, larger computers, lab¬ 
oratory models of the atmosphere, and 
perhaps synchronous satellites and 
ecology laboratories. 

The Commission recommends that 
a new research and development ca¬ 
pability be established—similar per¬ 
haps to a national laboratory—for the 
purpose of providing the necessary 
resources of scientific leadership and 
logistic facilities necessary in the 
mounting of an expanded interdisci¬ 
plinary program of weather and cli¬ 
mate modification. 

A national laboratory type of capa¬ 
bility is needed which could form the 
organizational and scientific man¬ 
power nucleus for an expanded re¬ 
search and development program. The 
costs of such a capability are not in¬ 
cluded in the foregoing estimates and 
recommendations. The organizational 
structure for this capability should 
provide machinery for assuring an 
interdisciplinary approach to weather 
and climate modification—encompass¬ 
ing the physical, engineering, biologi¬ 
cal and social sciences. 


One can not comment conclusively 
on the required nature, organization 
and financing of the new research and 
development enterprise described 
here. The need is clear; the question 
is how. The President’s Special Assist¬ 
ant for Science and Technology might 
wish to initiate the appropriate feasi¬ 
bility studies as to the nature, precise 
functions, and location of the new 
enterprise. 

ADMINISTRATION 

Existing Statutory and 
Administrate Directives 

a. Coordination of Scientific Policy 

Both the Federal Council on Science 
and Technology and the National 
Science Foundation have responsibili¬ 
ties with regard to scientific policy on 
weather modification research and 
operations. The Federal Council, un¬ 
der the Chairmanship of the Science 
Advisor to the President, is given 
general coordinating responsibility for 
science policy within the executive 
branch of the Government. This au- 


130 



thority is provided both by Reorgani¬ 
zation Plan No. 2 of 1962 and Execu¬ 
tive Order 10807 of March 13, 1959. 

The Federal Council, under the pro¬ 
visions of Executive Order 10807, is 
charged with the following responsi¬ 
bilities: 

Sec. 2. Functions of Council (a) The 
Council shall consider problems and 
developments in the fields of science 
and technology and related activities 
affecting more than one Federal agency 
or concerning the overall advancement 
of the Nation's science and technol¬ 
ogy, and shall recommend policies and 
other measures (1) to provide more 
effective planning and administration 
of Federal scientific and technological 
programs, (2) to identify research 
needs including areas of research re¬ 
quiring additional emphasis, (3) to 
achieve more effective utilization of 
the scientific and technological re¬ 
sources and facilities of Federal agen¬ 
cies, including the elimination of 
unnecessary duplication, and (4) to 
further international cooperation in 
science and technology. 

The Advisory Committee on 
Weather Control recommended that 
the National Science Foundation coor¬ 
dinate weather modification research. 
Under the authority of PL 85-510 and 


the legislative history thereof, the 
Foundation was expected to take the 
lead among the various Federal de¬ 
partments and agencies in the support 
of weather modification research. The 
Foundation complied by supporting 
sponsored research which provided 
the underpinnings for the more mis¬ 
sion oriented programs of other agen¬ 
cies. The Foundation established and 
has continued an annual Interagency 
Conference on Weather Modification, 
which has become a focus for govern¬ 
ment-wide program planning and co¬ 
ordination. 

At about the same time that the 
Federal Council for Science and Tech¬ 
nology was established in 1958, the 
National Science Foundation recog¬ 
nized the need for a formal interagency 
coordinating mechanism in connection 
with its newly assigned statutory re¬ 
sponsibility in the field of weather 
modification by establishing an Inter¬ 
departmental Committee on Weather 
Modification. During the June 1959 
meeting of the Federal Council there 
was discussion concerning the estab¬ 
lishment of a Committee to cover the 
field of Atmospheric Sciences. The 
President’s Science Advisor and the 
Director of the Science Foundation 
agreed that the Foundation existing 


131 



Interdepartmental Committee on 
Weather Modification could serve the 
needs of both the Federal Council and 
the Foundation. As a result, the Inter¬ 
departmental Committee on Weather 
Modification was formally reconsti¬ 
tuted as the Interdepartmental Com¬ 
mittee for Atmospheric Sciences 
(ICAS) and held its first meeting as 
such on September 9, 1959. 

Thus, general coordination on be¬ 
half of the President’s Executive Office 
with regard to research in this and 
related fields is exercised by one of 
the committees of the Federal Council 
on Science and Technology—the Inter¬ 
departmental Committee for Atmos¬ 
pheric Sciences (ICAS). Within ICAS 
is a panel on weather modification 
research which is chaired by the Head 
of the Section on Atmospheric Sci¬ 
ences of the Foundation. 

b. Support of Research by Indi¬ 
vidual Agencies 

Since 1940 the Federal Government 
has assumed an increasingly impor¬ 
tant role in the financing and conduct 
of scientific research and development 
in this country. This has been espe¬ 
cially true in the natural sciences and 
engineering. In recent years, however, 


the Foundation and other agencies 
have become significant supporters of 
research in the social, as well as the 
natural sciences. 

Research is supported not only to 
accomplish agency missions—usually 
as a forerunner to development—but 
also to increase the broad body of 
scientific and technical knowledge 
which underlies the future advance¬ 
ment of the Nation’s welfare, economic 
growth, and security. This is particu¬ 
larly true of basic research conducted 
primarily in academic institutions but 
also in government, industrial, and 
other laboratories focusing on funda¬ 
mental problems in science. 

The President’s budget for FY 1966 
contemplated an outlay of $14.5 bil¬ 
lion for research and development of 
which $4.9 billion was estimated for 
research and of which $2 billion is for 
basic research. 

Executive Order 10521 issued in 
March, 1954 and amended in March, 
1959 provides that: 

Sec. 4. As now or hereafter author¬ 
ized or permitted by law , the Founda¬ 
tion shall be increasingly responsible 
for providing support by the Federal 
Government for general-purpose basic 
research through contracts and grants. 
The conduct and support by other 


132 


Federal agencies of basic research in 
areas which are closely related to their 
missions is recognized as important 
and desirable, especially in response 
to current national needs, and shall 
continue. 

In other words the Foundation is 
charged with the support of basic re¬ 
search across the board and individual 
agencies are authorized to conduct 
and support such basic research as is 
necessary to sustain their operational 
missions. 

c. Conduct of Weather Modifica¬ 
tion Research Programs 

1. National Science Foundation 

Public Law 85-510 directs the Foun¬ 
dation “to initiate and support a pro¬ 
gram of study, research, and evaluation 
in the field of weather modification, 
giving particular attention to areas 
that have experienced floods, drought, 
hail, lightning, fog, tornadoes, hurri¬ 
canes, or other weather phenomena, 
and to report annually to the President 
and the Congress thereon.” The Foun¬ 
dation’s responsibility is therefore not 
only to support weather modification 
research, but to present an overview 
of the state of knowledge and effort 
in weather modification. It also pro¬ 


motes the exchange of information 
about the plans and programs of the 
various Federal agencies and provides 
for cooperation and coordination at 
the working level through various 
mechanisms, including the annual 
Interagency Conference on Weather 
Modification, where much of the cur¬ 
rent Federal interest in weather modi¬ 
fication has been kindled. 

Despite the broad statutory lan¬ 
guage cited above, the Foundation has 
elected to confine its research activ¬ 
ities to basic research, generally of 
the type that the Foundation would or 
could have supported anyway under 
its general authority to support basic 
research in the sciences. The Founda¬ 
tion selected as the first necessary task 
the development of a sound scientific 
basis for the art of weather modifica¬ 
tion. The stature of the Foundation 
gave creditibility to a field which had 
been plagued with a lack of technical 
and scientific understanding. The 
Foundation approached the leading 
meteorologists and other scientists 
with financial support to undertake 
scientific investigations to open the 
doors of knowledge. 

The research-support program is 
managed as an integral part of the 
Foundation’s over-all program of in- 


133 



vestigation in the atmospheric sci¬ 
ences. The dividing line between re¬ 
search in weather modification and 
basic research in the atmospheric sci¬ 
ences is difficult to draw, especially 
when so much more fundamental 
knowledge is required to provide the 
scientific basis for a successful na¬ 
tional program for developing new 
and improved weather modification 
techniques. 

Through grants with key university 
groups and through the contract sup¬ 
port of the National Center for Atmos¬ 
pheric Research (NCAR) the Founda¬ 
tion has given special emphasis to 
studies on the development of models 
to describe the natural processes 
which produce the clouds, the weather, 
and the general circulation of the at¬ 
mosphere. Many problems confront 
the designer of such a theoretical 
model, among which are the inade¬ 
quate observations of natural phenom¬ 
ena to establish the proper theoretical 
approach. It is difficult to determine 
how natural atmospheric phenomena 
may be made accessible to humaji 
intervention, and it is also difficult to 
assess the results of such intervention. 
The burden is therefore placed on the 
theoretician to make sufficient prog¬ 
ress in raising the level of physical 


understanding to commit the proposed 
model to theoretical analysis. 

Foundation support for weather 
modification research in 1965 totaled 
$2.0 million for 28 projects. The At¬ 
mospheric Sciences Program of which 
weather modification is a part has 
grown from $2.9 million in FY 1959 
to $23.2 million in FY 1965. 

Under PL 85-510 research programs 
conducted by the Foundation were 
rather expected to include cooperative 
programs with States. By implication 
the Foundation was directed to en¬ 
gage in applied research and develop¬ 
ment as well as basic research with 
regard to weather modification. Addi¬ 
tionally, the Foundation was author¬ 
ized to obtain by regulation or other¬ 
wise information it deems necessary 
to its program of study, research and 
evaluation in the field of weather 
modification. The statute also directs 
the Foundation to give particular at¬ 
tention to geographic areas which are 
afflicted with recurring damage from 
weather—flood, drought, hail, etc. 

(2) Department of Commerce 

The Weather Bureau, a part of the 
Environmental Science Services Ad¬ 
ministration (ESSA), has initiated a 
basic and applied research program in 


134 


the field of weather modification, hold¬ 
ing that this type of activity is con¬ 
sistent with and necessary to the ac¬ 
complishment of the basic mission of 
the Weather Bureau—namely, the pro¬ 
vision of increasingly accurate fore¬ 
casts and warnings of weather and 
flood conditions. 

Experiments on tropical clouds and 
hurricanes are conducted jointly with 
the Navy under Project STORMFURY. 
The clouds are studied in relation to 
the hurricane system and as they op¬ 
erate during undisturbed weather con¬ 
ditions. The technique used to explore 
the cloud mechanism has been silver 
iodide seeding using pyrotechnic de¬ 
vices called Alectos; a broader ex¬ 
perimental program is planned for the 
future. The project is in the research 
phase, and experimental operations 
have been performed to probe the 
mechanisms involved in convective 
motions in cumulus clouds over the 
ocean. Scientific experiments on the 
large-scale atmosphere appear to be 
necessary before the reduction of the 
severe storm hazard by manmade con¬ 
trol of convective phenomena can be 
realized. 

Development of theoretical models 
is continuing which are capable of 
reproducing and accounting for the 


natural processes which produce the 
weather and circulation of the atmos¬ 
phere. Special attention is being given 
to research dealing with the interac¬ 
tions at the ocean-atmosphere surface. 

In a recent report to the President, 
the Secretary of Commerce recom¬ 
mends an enlarged national program 
of weather modification and states his 
intention that the Environmental Sci¬ 
ence Services Administration (com¬ 
prising the Weather Bureau, Coast and 
Geodetic Survey and related agen¬ 
cies) take a leading role in such a 
program. 

(3) Department of Defense 

The Department of Defense has con¬ 
sistently carried on an active pro¬ 
gram of weather modification research 
as weather phenomena related to re¬ 
spective military missions of the three 
services. These are described below. 

(i) Air Force 

The program of the Air Force in 
cloud physics is centered around the 
activities of the Air Force Cambridge 
Research Laboratories at Hanscom 
Field, and is directed towards a study 
of the life cycle of clouds, utilizing 
ground radar and highly instrumented, 


135 



cloud-physics aircraft. Observations 
are made of the atmospheric electri¬ 
cal properties in the vicinity of the 
cloud environment which are coupled 
to the refractive index measurements 
before, during, and after cloud pene¬ 
tration. The dynamics of clouds are 
studied by both aircraft penetration 
and by stereo ground-camera net¬ 
works. This work is supplemented by 
laboratory studies of the micro-physi¬ 
cal properties of clouds. A cumulus 
cloud observational program is carried 
on in Florida during the summer 
months to obtain information on cu¬ 
mulus growth and precipitation. 

In an effort to establish a sound 
scientific basis for the development of 
fog forecasting and fog-modification 
techniques, the Air Force has under¬ 
taken a comprehensive field research 
program to characterize and under¬ 
stand the natural life cycle and vari¬ 
ability of warm fog. The program has 
been nicknamed Project CATFEET. 
Cape Cod, Mass., was selected as the 
site for this research, with Otis Air 
Force Base being the main instru¬ 
mented facility. The first data were 
obtained at this site during July and 
August of 1964. The formation, de¬ 
velopment, and dissipation of the fog 
was documented by intensive meas¬ 


urements of the significant meteoro¬ 
logical parameters utilizing a micro- 
meteorological tower and a cloud- 
physics research facility on the base. 
An 11-station mesometeorological net¬ 
work extending over the southwest or 
upwind section of the Cape was also 
placed in operation. A laser disdrom- 
eter, for measuring droplet size, is 
among the new instruments which 
were developed especially for this 
program. More data from this program 
was gathered during 1965 and are now 
being reduced and analyzed. 

(ii) Army 

Research in weather modification 
has been centered primarily around 
the Army Electronics Research and 
Development Laboratories in New 
Jersey and their contractors. The ob¬ 
jective of the Army research program 
is to obtain a better understanding of 
the physical concepts of rainmaking. 
Activity has been centered in three 
particular areas of effort; namely, the 
basic studies of cloud physics mecha¬ 
nisms, the basic understanding of pre¬ 
cipitation phenomena, and the basic 
concepts of modification. On the 
whole, work in cloud physics has been 
concentrated upon convective cloud 


136 



systems. A program of thunderstorm 
research was conducted during the 
summer in the area of Flagstaff, Ariz., 
where basic cloud mechanisms were 
studied which might provide possible 
applications to the modification of 
cumulus-cloud dynamics and nuclea- 
tion. A small program has been car¬ 
ried out in the areas over the Great 
Lakes, where a considerable amount 
of snow is usually obtained. An effort 
was made to learn more about the 
temperature inside clouds by studying 
the formation of ice crystals after 
seeding with dry ice. Other studies 
have included nuclei counts within 
clouds, the collection of raindrop 
spectra, comparison of raindrop size 
at different wind speeds, and the co- 
alescense of raindrops. 

(iii) Navy 

The efforts by the Navy in weather 
modification are centered around two 
phenomena: warm fog and trade winds 
cumulus clouds. The principal labora¬ 
tory and field work is carried out by 
scientists attached to the Naval Re¬ 
search Laboratory. Work is in progress 
along three general lines: (a) Develop¬ 
ment of aircraft instruments possess¬ 
ing fast response and accuracy to 


measure the water content and cloud- 
droplet size distribution in clouds. 

(b) Studies of the origin and nature of 
cloud condensation nuclei and of the 
role of nuclei in cloud and fog forma¬ 
tion, stability, and precipitation, and 

(c) Exploration of the feasibility of 
using tracer techniques to study cloud 
motions and the interchange between 
a cloud and its environment. 

Work in weather modification being 
performed at the Naval Ordnance Test 
Station at China Lake during 1964 has 
been in the field of development of 
means for changing weather and cloud 
conditions for tactical purposes. Re¬ 
sponsibilities for planning and co¬ 
ordination of naval activities in the 
environmental-control research area 
has been assigned to the Navy Weather 
Research Facility located at Norfolk, 
Va. Included in the current program 
already underway are the following: 

(a) The use of the operations re¬ 
search approach to speed up the 
eventual applications of environmental 
control in naval operations, (b) Con¬ 
sideration of the applications of cur¬ 
rent and potential weather techniques 
in the support of naval operations, 
(c) Planning and coordination of the 
Navy portion of the Project STORM- 
FURY program. 


137 



(4) Department of Interior 

Due to the interest by some mem¬ 
bers of Congress (principally from 
western States) in an aggressive pro¬ 
gram of weather modification, the Bu¬ 
reau of Reclamation has been directed 
through appropriation language to in¬ 
augurate a weather modification re¬ 
search program with emphasis on the 
engineering aspects. The program was 
started during FY 1962. It is directed 
toward learning if it is possible to in¬ 
crease inflow into the Bureau’s reser¬ 
voir system. 

The Department of the Interior’s in¬ 
terest in weather modification is con¬ 
cerned with the atmospheric water 
resources of the Nation and the possi¬ 
bility that weather modification will 
supply additional precipitation and 
runoff to the river basins which feed 
the Bureau of Reclamation reservoirs. 

Planning within the Bureau of Rec¬ 
lamation points to a possible 25-year 
program. The Bureau program is 
founded in part on the continuation 
of a number of programs initially de¬ 
veloped under Foundation sponsor¬ 
ship which have now matured to the 
point where engineering research can 
be established. Examples include con¬ 
tinuation by the University of Nevada 


of the artificial seeding of clouds by 
the Humboldt River Basin and an in¬ 
creased effort at South Dakota School 
of Mines and Technology. 

To manage and coordinate the pro¬ 
gram an Office of Atmospheric Water 
Resources was established in Denver, 
Colorado. A small group of engineers, 
meteorologists, and administrative 
personnel have been assigned to staff 
this new office. The program will be 
conducted largely as a contract activ¬ 
ity of the Bureau of Reclamation. 

(5) Department of Agriculture 

The continuation of Project SKY- 
FIRE represents the primary effort of 
the Forest Service in the area of 
weather modification during FY 1964. 
Project SKYFIRE is a research study 
on the electrical nature of thunder¬ 
storms and the relationships of forest 
fires resulting from cloud-to-ground 
lightning charges. Attempts are being 
made to modify thunderstorms in 
ways that will decrease the number 
and intensity of cloud-to-ground light¬ 
ning. The project has two long-range 
objectives: (a) To obtain a better un¬ 
derstanding of the occurrence and 
characteristics of lightning storms and 
lightning fires in the northern Rocky 


138 



Mountain region; and (b) to investi¬ 
gate the possibility of preventing or 
reducing the number of lightning fires 
by applying techniques of weather 
modification. 

The Department plans to continue 
the study of the relationship between 
lightning discharge and forest-fire ig¬ 
nition. Points to be considered are the 
characteristics of the lightning stroke 
which produces ignition. In some 
cases, lightning strokes may be pro¬ 
longed by the bridging of several 
thunderstorm cells which produces 
more effective ignition than a shorter- 
duration stroke of much higher peak 
intensity. Investigation is also contin¬ 
uing on the effects of seeding upon 
the electrification mechanism, and the 
Department hopes that some informa¬ 
tion will be derived as to the mecha¬ 
nism whereby cloud seeding will af¬ 
fect the buildup of charge in the 
thunderstorm. 

Problems 

a. Disparity Between Congres¬ 
sional Interest in Weather Modifica¬ 
tion and National Science Foundation 
Policy 

The legislative intent of PL 85-510 
regarding the Foundation is fairly 
clear; the Congress desired an aggres¬ 


sive research program covering both 
research and development. The Foun¬ 
dation has felt until the last year or 
two that the state of the art dictated 
a more conservative approach. The re¬ 
sult has been that the Foundation’s 
efforts have largely been in the award 
of grants for research in atmospheric 
sciences of a type that could have 
been made under the basic authority 
of the Foundation in the absence of 
the Weather Modification Act (PL 
85-510). It was also the hope of Con¬ 
gressional sponsors of PL 85-510 that 
the Foundation would continually ap¬ 
praise and evaluate the research under 
way in the U. S. and other countries 
and would provide the Congress with 
“readings” on the prospects of weather 
modification. The Foundation has 
largely refrained from this type of ac¬ 
tivity on the ground that research re¬ 
sults have not been of a sufficiently 
extensive nature that would sustain or 
justify evaluative judgments. 

b. Duplication in Research Activ¬ 
ities and Coordinative Responsibili¬ 
ties 

The intention of PL 85-510 was that 
the Foundation would carry primary 
responsibility within the Executive 


139 



Branch for weather modification re¬ 
search and would assume leadership 
of the research activities of the other 
Federal agencies in this field. For the 
first few years, the Foundation as¬ 
sumed and held the initiative, with 
respect to coordination as well as re¬ 
search. It was through the early lead¬ 
ership of the Foundation that a con¬ 
tinuing and orderly interchange of 
research plans, proposals and findings 
among the interested Federal agencies 
was provided. In subsequent years, 
as a result of the creation of the Fed¬ 
eral Council on Science and Technol¬ 
ogy with its coordinative responsibil¬ 
ity for science policy across-the-board 
and as a consequence of the Founda¬ 
tion policy decision to generally con¬ 
fine its activities to the support of 
basic research on weather processes, 
the coordinative role initially asserted 
by the Foundation passed to the Exec¬ 
utive Office of the President. Within 
the past three years the situation re¬ 
garding research activity has also 
changed. Two other prominent civilian 
agencies now “operate” in the weather 
research field—the Weather Bureau 
and the Bureau of Reclamation. 

So long as weather modification ac¬ 
tivities are largely confined to the 
basic research phase, this duplication 


does not constitute a significant prob¬ 
lem. Indeed, it is probably well that 
there be mild competition among 
agencies. In a field of science that is 
both new and critical a diversity of 
approach is much to be preferred to 
a centering of responsibility, funds 
and research direction in a single spot. 
Certain aspects of weather modifica¬ 
tion activities have now reached the 
applied research and operations phase, 
with regulatory activity not far away. 
An expanded fundamental research 
program is now desirable and feasible, 
some of which involves significant 
logistics aspects. 

some Factors AKeclfng 
Assignment ot Responsimtity 

Following are some of the consider¬ 
ations which need to be taken into 
account by the National Science Foun¬ 
dation, other Federal agencies, the 
President, and the Congress in fixing 
responsibility for weather and climate 
modification activities, 

(1) There is need to bridge the 
organizational gap between labora- 


140 



tory research and large scale field ex¬ 
periments; this gap can exist even in 
the basic research aspects. 

(2) There is need for organiza¬ 
tional arrangements for enough ap¬ 
plied research to develop the field, 
while preserving scientific objectivity 
in the basic research effort. The eco¬ 
nomic, political and dramatic aspects 
of weather and climate modification 
operations must not be permitted to 
crowd out the basic research. 

(3) There is need for biological 
and social science research to go hand 
in hand with the physical science and 
engineering research in support of the 
missions of all agencies, contractors 
or grantees concerned with weather 
modification. 

(4) There is need to preserve 
diversity in the research effort, but 
there is the need also to establish a 
Federal organizational mechanism for 
accomplishing what can not be done 
through diverse research activities. 

(5) Responsibility should be 
clearly assigned for the formulation of 
arrangements for appropriate scienti¬ 
fic cooperation with the governments 
of other nations. 

(6) Adequate enforcement 
power needs to be provided an admin¬ 


istering agency so as to insure the 
filing of information relative to all 
weather modification field experi¬ 
ments and all commercial operations. 

[7] In the absence of compel¬ 
ling reasons otherwise, the agency as¬ 
signed regulatory functions should 
have a regional or field office estab¬ 
lishment. 

(8) The conduct of research 
and development in this field should 
be kept insulated from activities in¬ 
volving the regulation of weather 
modification operations, but at the 
same time the two types of activity 
should be sufficiently proximate or¬ 
ganizationally to assure immediate ac¬ 
cess to data derived from the opera¬ 
tions being regulated. 

Long-Range JUiernaiivos 

a. Continuation of the Status Quo 

The case for this alternative is that 
in a field as complex and uncertain as 
weather and climate modification, the 
best efforts of the four principal agen¬ 
cies now engaged in weather research 
are needed—Defense Department, 
ESSA—Weather Bureau, National Sci- 


141 



ence Foundation, and the Department 
of the Interior. None of the existing 
programs are in competition and all 
of them are necessary at the present 
stage of research and development. 

There is an ultimate need for a 
more specific assignment of responsi¬ 
bility for weather and climate modifi¬ 
cation activities in the Government. 
Until the nature of the scientific feasi¬ 
bilities are further identified, how¬ 
ever, the direction which such an as¬ 
signment should take is not clear. For 
example, if in the further develop¬ 
mental phases, activity by a very 
large number of aircraft, over an in¬ 
definite period is required, this logis¬ 
tics essential might weigh heavily in 
favor of assigning the operational mis¬ 
sion to the Air Force. If, on the other 
hand, for example, it becomes neces¬ 
sary to bring together large numbers 
of university groups and commercial 
operators into a combined research 
and operational effort, the ESSA— 
Weather Bureau or the Department of 
Interior with their field establishments 
might draw this assignment. 


b. Assignment of Responsibility 
for Weather and Climate Modification 
to the Department of Commerce 

The following factors tend to favor 
such an assignment: 

(1) A close and inextricable 
connection exists among weather pre¬ 
diction, weather research, weather 
modification and operation. Intensified 
data collection, dissemination, evalua¬ 
tion, storage and modeling activities 
recommended as a key part of the 
weather and climate research activity 
are closely related to the weather pre¬ 
diction activities of the Weather Bu¬ 
reau. Understanding more about 
weather and climate processes is in¬ 
dispensable both to modification and 
to prediction activities. 

(2) The Weather Bureau has 
the logistical capability for mounting 
weather modification operations, in¬ 
cluding large scale field experiments. 

(3) The Weather Bureau is a 
logical agency to represent the U. S. 
Government in the intergovernmental 
aspects of weather modification. The 
Bureau has always served as the offi¬ 
cial United States link with the World 
Meteorological Organization. 


142 



c. Assignment of Responsibility 
for Weather and Climate Modification 
to the Department of the Interior 

The following factors tend to favor 
such an assignment: 

(1) The phase of weather mod¬ 
ification now most nearly ready for 
aggressive applied research, develop¬ 
ment, and actual operational activity 
—the augmentation of precipitation; 
—is vitally linked to the water man¬ 
agement program of the Bureau of 
Reclamation. 

(2) Weather modification ac¬ 
tivities including basic and applied re¬ 
search relate closely to those eco¬ 
nomic and political interests that are 
concerned with the overall mission 
and programs of the Interior Depart¬ 
ment. This would go far to assure 
priority attention and adequate fund¬ 
ing of the weather and climate modi¬ 
fication program. 

(3) Weather modification ac¬ 
tivities are highly compatible with the 
basic long range mission of the In¬ 
terior Department—the conservation, 
development and use of scarce nat¬ 
ural resources. 

(4) The Department of Interior 
has field offices throughout the nation. 


d. Assignment of Responsibility 
for Weather and Climate Modification 
to the National Science Foundation 

The following factors tend to favor 
such an assignment: 

(1) Only in the Foundation 
would the basic research aspects of 
weather and climate modification be 
reasonably secure from “crowding 
out” by operational activities. Even if 
the Foundation should also carry on 
the essential developmental and oper¬ 
ational activities, the agency’s habits 
and the dedication of its staff to the 
promotion of basic research would 
assure adequate support of the basic 
scientific phases. 

(2) The Foundation already has 
the unique capability for providing an 
interdisciplinary approach to both the 
research and developmental aspects 
of the function, making sure that the 
physical, biological, social science and 
engineering facets are not neglected. 
This capability exists through the 
Foundation’s authority to support 
basic and applied research in the 
fields related to weather modification. 

(3) The Foundation has had 
seven and a half years of experience 
in research leadership with regard to 
weather modification. Other agencies 


143 



have become accustomed to looking 
to the Foundation for initiative and 
support for weather modification re¬ 
search. 

e. Other Considerations 

The assignment of responsibility 
within the Federal Government for 
weather modification would be little 
more than a routine matter of internal 
government coordination were it not 
for the fact that the entire approach 
to the scientific and practical prob¬ 
lems of weather modification has 
recently undergone a subtle yet pro¬ 
found change. Five years ago atten¬ 
tion was rather vaguely focused on 
the physics of clouds and the possible 
consequences of cloud seeding. The 
development of techniques for me¬ 
teorological modeling, the feasibility 
of computers 100 to 1,000 times faster 
than those now available, and the 
rapidly expanding capabilities for 
global observations have escalated 
the problem of weather and climate 
modification into new dimensions of 
scientific and technological opportun¬ 
ity. 

The mode of research management 
under which a national program has 
been conducted in the past (with its 
advantages and its shortcomings) may 


be completely inadequate for the 
character and the scale of the work 
that will be required in the future. 

In the event of dramatic scientific 
progress, weather modification and 
climate control could very well de¬ 
velop into a major priority program. 
In this event, the program would need 
a new governing statute and an up¬ 
grading in terms of organizational sta¬ 
tus, with the possible creation of a 
new independent agency for the pur¬ 
pose. 

The major alternatives in assigning 
organizational responsibility for 
weather and climate modification ac¬ 
tivities have been described. Before 
considering possible changes in or 
combinations of these possibilities it 
would be well to enumerate some of 
the factors tending to militate against 
assignment to the agencies discussed, 
and to consider the general problem 
of coordination. 

f. Disadvantages of Particular 
Agencies 

(1) The Reclamation Bureau is 
limited in geographic jurisdiction to 
the Western States. Significant amend¬ 
ment to its statutory authority would 
have to be made were it to undertake 
responsibility for weather and climate 


144 



modification. Also, only one aspect of 
weather modification—precipitation 
augmentation—is related to the over¬ 
all mission of the Bureau. These lim¬ 
itations do not extend to the other 
water, land, recreation, wildlife and 
mineral functions of the parent De¬ 
partment—the Department of Interior. 

(2) The National Science Foun¬ 
dation lacks the logistical capabilities 
for developmental and operational ac¬ 
tivities in the field, although these 
could be acquired. 

(3] The Weather Bureau lacks 
broad authority and experience in the 
conduct and support through grant 
and contract of basic scientific re¬ 
search, although its in-house capabil¬ 
ity in this regard has been improving 
and extra-mural capability could be 
acquired. 

g. Coordination 

Under no conceivable set of condi¬ 
tions could all concern with research 
relating to weather and climate be 
confined to a single agency. This leads 
to obvious problems of coordination 
and related problems of allocation of 
resources of funds and manpower, 
sharing and channeling of informa¬ 
tion, and scientific emphasis and di¬ 
rection. 


The very close interrelationships 
among basic research, applied re¬ 
search, development, operations, reg¬ 
ulation, weather prediction, and the 
missions of the various interested and 
concerned agencies add to the diffi¬ 
culties. The coordination problem, of 
course, tends to be roughly commen¬ 
surate with the degree to which re¬ 
sponsibility is centralized or dispersed 
among the agencies. 

conclusions and 
Recommendations 

The Commission has considered 
carefully the problems attendant upon 
the assignment of responsibility for 
weather and climate modification ac¬ 
tivities within the Exeuctive Branch 
of the Federal Government. 

There are no easy solutions to these 
questions. The Commission believes 
the adoption of the following recom¬ 
mendations would significantly im¬ 
prove the effectiveness of the Nation’s 
efforts in this field, and would facili¬ 
tate the achievement of the scientific 
and other objecives specified else¬ 
where in this report. 


145 



a. Responsibility for Research, 
Development, and Operations 

The Commission recommends: ( 1 ) 
the assignment of the mission of de¬ 
veloping and testing techniques for 
modifying weather and climate to a 
single agency in the Executive Branch 
of the Government—for example to 
the Environmental Science Services 
Administration of the Department of 
Commerce or to a completely new 
agency organized for the purpose; (2) 
the continuance and expansion of re¬ 
search in the atmospheric sciences by 
the National Science Foundation, in¬ 
cluding its program directed at pro¬ 
viding a satisfactory scientific basis 
for weather and climate modification 
and the maintenance of the National 
Center for Atmospheric Research as a 
basic research facility for this pur¬ 
pose; and (3) the conduct or support, 
pursuant to Executive Order 10521, of 
such basic and applied research by 
other Federal agencies as is required 
for their varied missions as well as 
the conduct of operational activities 
necessary for the accomplishment of 
such missions (e.g., precipitation aug¬ 
mentation for the reservoir system of 
the Bureau of Reclamation; lightning 


suppression by the U. S. Forest Serv¬ 
ice; military applications by the De¬ 
partment of Defense; etc.). 

The degree of the Foundation’s spe¬ 
cial attention to this field, including 
the support of related research in 
other affected disciplines, should be 
reviewed from time to time in the light 
of the progress of the overall national 
program. The Foundation needs to 
continue the vigorous support of basic 
research in the atmospheric sciences 
because fundamental knowledge so 
derived is a necessary underpinning to 
technological progress in weather and 
climate modification. 

The agency assigned the mission of 
developing and testing techniques for 
modifying weather and climate, as a 
part of its overall mission, should 
have major but not exclusive respon¬ 
sibility in collaboration with the State 
Department for formulating and 
implementing weather and climate 
modification programs involving inter¬ 
national collaboration with the gov¬ 
ernments of other nations. The gov¬ 
ernment’s activities in international 
cooperation can be substantially as¬ 
sisted by the participation of the Na¬ 
tional Academy of Sciences. 


146 



b. Regulation 

The Commission recommends that 
responsibility for appropriate Federal 
regulation of weather and climate 
modification activities to aid the Fed¬ 
eral Government’s program of research 
and development and to protect the 
general public be kept separated from 
research and development activities 
while assuring prompt and full avail¬ 
ability to such activities of data de¬ 
rived from the regulation of commer¬ 
cial and other operational activities. 
Such a combination might be 
achieved, for example, by assigning 
the regulatory function to some part 
of the Department of Commerce not 
concerned with weather and climate 
research and development. 

Earlier in this report there has been 
discussed the nature of minimum reg¬ 
ulatory action which may be required 
on the part of the national Govern¬ 
ment to assure the integrity of ex¬ 
periments conducted by Federal agen¬ 
cies or their grantees and contractors. 
It should be pointed out in this con¬ 
nection that Federal agencies and 
their contractors and grantees them¬ 
selves will necessarily be subject to 
some of the same types of regulation 
that apply to commercial operations. 


A Federal agency field experiment in¬ 
volving large-scale cloud seeding for 
example, can cause the same inter¬ 
ference with other scheduled experi¬ 
ments as can cloud seeding conducted 
by a commercial operator. 

Consequently, Federal agencies will 
need to be subject to many of the 
rules and regulations issued by the 
type of regulatory unit recommended 
above. Insofar as the regulation in¬ 
volves requirements of notice of ex¬ 
periments, licensing of activities and 
the like, there would seem to be rea¬ 
son why all Federal agencies should 
be subject thereto. The regulating 
agency should also have the power to 
resolve minor conflicts between agen¬ 
cies, such as the precise timing of 
particular experiments. Any major 
disagreements would involve policy 
and administrative coordination as 
discussed below. 

c. Inter-Agency Coordination of 
Policies and Program Activities 

The Commission recommends that 
there be established within the Office 
of Science and Technology (OST) a 
special mechanism for the coordina¬ 
tion of weather and climate modifica- 


147 



tion programs and for recommending 
such steps as may be appropriate for 
effecting a unity of governmental pol¬ 
icy in this field. 

If the general mission of developing 
the technology for climate modifica¬ 
tion is assigned to a single agency, 
present overlap and lack of concerted 
effort among the various agencies will 
be remedied to a considerable extent. 
Due to the great importance of the 
field, however, and because of the 
necessity of maintaining an interdis¬ 
ciplinary and international approach 
to weather activities, it is believed 
that continuing attention must be 
forthcoming from the Executive Office 
of the President. Consequently, some 
mechanism concerned solely with 
weather and climate modification, 
with emphasis on the development 
and operational side, needs to be es¬ 
tablished within the OST. The OST’s 
concern should embrace funding, basic 
research, applied research, develop¬ 
ment, testing and evaluation. Such a 
mechanism could take over from ICAS 


the weather and climate modification 
components. ICAS could continue to 
be concerned with atmospheric re¬ 
search. 

d. An Advisory Committee 

The Commission also recommends 
the utilization of the National Acad¬ 
emy of Science and the National 
Academy of Engineering for continu¬ 
ing review and advice regarding the 
national program of weather and cli¬ 
mate modification. 

Both the President’s Science Ad¬ 
visory Committee and the Congress 
need to be able to obtain scientific and 
public policy advice from a group of 
knowledgeable people from outside 
the Government. This need could per¬ 
haps be met by the appointment of a 
standing committee in the National 
Academy of Sciences in cooperation 
with the National Academy of Engi¬ 
neering. Such a committee includes 
persons with experience in the physi¬ 
cal sciences, engineering, the biologi¬ 
cal sciences and the social sciences. 


148 



APPENDIX 


Bibliography of reports remaining to 
be published of research and studies 
performed under National Science 
Foundation grants and contracts in 
support of the work of the Special 
Commission on Weather Modification. 

1. Biological Aspects of Weather 
Modification, Ad Hoc Weather Work¬ 
ing Group, to be published in the 
March, 1966 issue of the Bulletin of 
the Ecological Society of America. 

2. Human Dimensions of Weather 
Modification, W. R. Derrick Sewell 


(Editor], to be published in the Uni¬ 
versity of Chicago Department of 
Geography Research Papers in Febru¬ 
ary, 1966. 

3. Weather Modification: Law, Con¬ 
trols, Operations, H. J. Taubenfeld, 
et al, to be published by the National 
Science Foundation in January, 1966 
(NSF-66-7J. 

4. International Relations and 
Weather Modification, Leonard E. 
Schwartz, to be published by author. 


149 





