Future Research in Weather Modification 
Howarp T. OrvILLE 
Vice President, Beckman & Whitley, Inc., San Carlos, California 
Abstract—The paper outlines the present status of research in cloud physics and weather 
modification, and attempts to emphasize the need for expanded research in certain areas of 
cloud physics. Several suggested outlines for research projects are given. 
Introduction—W eather modification as treated 
in this discussion deals with competent research 
designed to increase precipitation, prevent hail, 
inhibit lightning, or dissipate fog. Present scien- 
tifie efforts at weather modification follow quite 
closely experimental methods and techniques de- 
veloped by Langmuir and others [1953]. These 
methods use nucleating agents dispersed into the 
cloud by ground generators or by aircraft flying 
over, in, or under the base of clouds to create 
artificial precipitation or to bring about other 
changes in state in the clouds. Solid carbon di- 
oxide (dry ice) or silver iodide are the two most 
commonly used nucleating agents although oth- 
ers such as cupric sulphide, hydrogen chloride, 
and a number of clay minerals are effective as 
freezing nuclei. 
Many uncertainties exist as to the exact man- 
ner in which the nuclei affect the clouds to bring 
about the change of state from vapor to water 
or solid form when they are seeded. This, then, 
brings us to the field of cloud physics. 
Cloud physics and weather modification— 
Houghton [1959] recently has reviewed the cur- 
rent problems in cloud-physics research. One 
cannot read this excellent review without be- 
coming singularly impressed with the urgent 
need for expanding and accelerating the research 
effort in cloud physics and the precipitation 
processes. Not to be overlooked are studies of 
the chemistry and electrical effects in the at- 
mosphere. 
Houghton’s review of homogeneous nuclea- 
tion, condensation nuclei, freezing nuclei, pre- 
cipitation processes, and natural precipitation 
mechanisms repeatedly emphasizes the broad 
gaps in our knowledge. He concludes that there 
are many challenging problems that only can be 
answered by both laboratory and field research. 
He particularly stresses the need for more in- 
strumentation to measure the parameters of 
cloud physics. 
A casual review of the papers presented at this 
meeting serves to impress the reader with the 
many unsolved problems of atmospheric proc- 
esses. Almost every paper reports lack of ob- 
servational or experimental data. Frequently, 
assumptions are made to justify later deriva- 
tions or arbitrary criteria are set up to make it 
possible to justify the conclusions. It seems to 
me that many of the assumptions are the same 
ones used when I was a student 30 years ago. 
Of course, much progress has been made but 
in comparison with other fields of science, medi- 
cine and atomic energy, for example, the prog- 
ress in understanding atmospheric processes 
seems quite insignificant. Until more progress is 
made in our understanding of precipitation 
mechanisms, efforts at weather modification are 
limited to our present knowledge. 
Need for basic research—The Advisory Com- 
mittee on Weather Control [1957] recommended 
that encouragement be given for the widest pos- 
sible competent research in meteorology and re- 
lated fields. The report pointed out that a vigor- 
ous research program should be established with 
adequate provisions to maintain continuity and 
reasonable stability for long-term projects. It 
stressed the fact that emphasis should be placed 
on sponsoring talented men and their projects. 
A National Institute of Atmospheric Research 
—The Committee on Meteorology [1958] of the 
National Academy of Sciences - National Re- 
search Council has proposed the establishment 
of a National Institute of Atmospheric Research. 
This Institute would be devoted exclusively to 
basic atmospheric research. It recognizes the 
formidable problems that the meteorologist faces 
in the field of cloud physics and would establish 
a research program commensurate with the 
global importance of weather. The program pro- 
posed by this Committee deserves the strongest 
possible support by all scientists having an in- 
terest in atmospheric research, 
Cloud physics and planetary research pro- 
gram—Ackerman [1959] has suggested a two 
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