WSP07672

• File Number: 8040.980
• Description: Section D General Studies-Weather Modification
• State: CA
• Date: 2/7/1951
• Author: CAChamberofCommerce
• Title: Scientific Economic and Legal Aspects of Weather Modification
• Water Supply Pro - Doc Type: Report/Study

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Act of God and that there wasn't sufficient evidence to prove hQ~ agency. Eight
years afte~nard F.atfie~d ~pparently in amusement rather than anger, claimed that he
had never received a cenny of his fee.

For various reasons, interest in rainmaking in this country died ~own in the late
192)' s an" "'as not revived again until after ':1orld "'ar II. However scientists in
SOloe mropean countries continued to ex?eriment during the 1930's. The chain of
events which brought weather control to the forefront of public interest in th~s
COWltry after the ",e.r ~rere set off largely by accident. Dr. Irvin/; Langmuir, 1932
winner of a Fobel "rhe in chemistry, during the >rar >Tas assigned by the U. S. ArrIIy
to m~<e snocinl investig~tions on the ber.avior of fogs. In the course of these he
made some-discoveries "hich fitted neatly into the pattern of scientific theories
being formulated by meteorologists on the causes of precipitation.

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After the war ~r. Langcruir's attention wes directed almoet exclusively to the field'
of "'eather control. A number of other scientists: chemists, physicists ~nd meteor-
ologists also had turned their attention to this field. The result has been a rapid
fire series of discoveries "hich have given some of the most eminent scientists in
our country a strong conviction tr~t weather can be greatly modified during preva-
lence of certain conditions a,nd by techniques easily IIll'de available at a low cost.
So impressive have been some demonstrations that the armed services for the past
three years have been spending nearly a million dollars a year for experimentation
on weather control. Consequently, many recent discoveries are highly secret in the
interest of national safety. Eor'Tever, a great deal of knowledge is public property
end it is the purpose here to present a brief evaluation of the present situation
as it appears from tho most recent datA available.

\;eathor modification ectivities at this time consist almost entirely of attempts to
change the amount of preci?itation from th~t ~hich would occur naturally. These
make use of techniques based upon a certain process known as "cloud seeding" or
"cloud nucleation". This term simply means the introduction of a large number of
fine cI"'/stnls of certain subste.nces into the clouds. T~o substances most used are
dry ice and silver iodide. If dry ice is used, the crystals m~y be sprayed or
s'prinklec. frolll an airplane. It has been said that anyone who ceL rent a plane and
?roc~re a bucket of dry ice Can start a rainstorm. In the use of silver iodide the
most favored technique ie the employment of generators on the ground which vaporize
the substance so that the particles will rise into the clouds on updrafts of air.
The generators can be moved quickly from one place to another so 8S to take advantage
of clo~d movements and changes in wind direction.

The most enthusiastic advocates of man's ability to control weather do not now claim
that rainfall can be induced under any or all conditions. The state of the atmos-
phere must be favorable. That is, conditions must be such that there probably would
be precipitation even if no human abency butted into the situation. To put it in a
homely way, I"e cannot load the gun; we can only wait until nature has loaded it.
Under normal conditions, i. e. if there is no human interference, nature may or may
not :lull the trie;ger. L9rge numbers of loaded gune, in the form of rain clowis,
dri:t over us ,rithout delivering an;{ moisture.

I,jpn's best efforts, in the >Tords of a scientist in the U. S. ''leather Bureau "can't
pull the trigger until the gun is loaded." Some recent observations suggest that one
might go even farther and maintain that human agencies really ere too feeble to null
the trigger. It a?pears that precipitation is the end result of a chain reactio~.
said chain consisting of several links. The reaction cannot take effect unless all
the links are present and in their )ropsr places. Under these conditions nature is
constantly exerting pressure at one end of the series ,,'!lich may or may not be suffi-
cient to set off the precipitation at the other. Then the best efforts of which
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