Science, and transportation united states senate

River watershed. After 1954 ground based silver iodide generators

replaced aircraft seeding, and target and control areas were set up

for evaluation. Since 1956 selection of seeding days was randomized.

Following the 1974 season, seeding operations were suspended, and a

reevaluation of the project was undertaken, preparatory to a redesign

of the seeding operations. A restricted area pilot project was underway

to study techniques of seeding with salt, in view of the warm clouds

passing over the area. 38

The Ensenada project on the Baja California Peninsula has been

conducted with the intention of evaluating cloud seeding techniques

for augmenting water resources in this arid region, where both sur-

face and ground water are scarce. Since 1970, experiments have been

carried out by the Secretary of Hydraulic Resources in the northern

part of the peninsula, where seeding is performed during the winter

rainy season, using ground-based generators. Precipitation increments

of 10 to 15 percent were reported over the 9,000-square-kilometer

target area, based on results of a 5-year period of operation of this

35 Ibid., pp. 13-15.

36 Ibid., p. 39.

37 Cbnrak. "Weather Modification Activity Reports : Calendar Year 197o," 1976, p. 51.

37a Kraemer, Dieter (report on recent weather modification activities in Mexico), in "Pro-

ceedings of Conference on Weatber Modification. Today and Tomorrow," 2d annual meeting

of the North American Interstate Weather Modification Council, Kansas City, Mo., Jan. 15-

16. 1976, publication No. 76-1, pp. 85-88.

33 Ibid., p. 85.

420

of the state to contract continuation of this project to an American

firm, which would employ aircraft seeding. 39

A joint project was established in 1973 by the National Council of

Science and Technology, the Institute of Geophysics at the Univer-

sity of Mexico, and the Federal Ministry of Hydraulic Resources,

with the purpose of carrying out cloud seeding operations in the area

of the Chichinautzin Sierra, near Mexico City, to augment water sup-

plies. Initial seeding operations, begun in 1974, were accomplished

with ground-based generators, with the intention to expand into

aircraft seeding later if advisable. Based on analysis of data from

the first 2 years of these randomized operations, the average precipita-

tion increments over or near the target area were reported to range

from 15 to 75 percent, depending upon the specific location. 40

Other pilot or demonstration projects were underway during 1975

and 1976 in southern Baja California and in the Yacamiya River

Basin, and the start of three new programs within a year was being

contemplated. 41

In an earlier report Kraemer discussed progress on the projects

discussed above and also included a discussion on the history of

experimental weather modification projects in Mexico. The earliest

experiments there were conducted in the neighborhood of Mexico City

in 1947. Subsequent cloud seeding experiments were sponsored by

various government agencies, some universities, and a few private

companies. Lack of adequate design and control led to suspension of

most of the earlier projects, their subjective, nonstatistically signifi-

cant evaluations providing no valid conclusions. 42

people's republic of china

In 1974 a delegation of U.S. meteorologists, representing the Amer-

ican Meteorological Society (AMS), visited a number of meteorolog-

ical institutions in the People's Republic of China, at the invitation

of the Chinese Meteorological Society. As part of their overall orienta-

tion to the activities of their counterparts, they learned about weather

modification research and operational projects in Red China. 43 Such

activities are sponsored principally by the Institute for Atmospheric

Physics of the Academia Sinica and by the Central Meteorological

Bureau, both in Peking.

To the visitors there appeared to be an emphasis on application of

weather modification technology over research, and there was an

attempt to incorporate the cooperation and suggested ideas from the

local peasants into the use of such technology. This latter emphasis

has even motivated some experiments which are designed to verify

some of the plausible weather folklore. 44

» Ibid., p. 86.

41 Ibid., p. 88.

42 Kraemer. Dieter, "Cloud Seeding Activities in Mexico," in "Proceedings of Conference

on Weather Modification — A Usable Technology : Its Potential Impact on the World Food

Crisis," North American Interstate Weather Modification Council, Denver, Colo., Jan. 16-17.

1975, pp. 110-120.

« Kellogg. William W., David Atlas. David S. Johnson. Richard J. Reed, and Kenneth C.

Spongier. "Visit to the People's Republic of China : A Report From the A. M.S. Delegation,"

Rulletin of the American Meteorological Society, vol. 55, No. 11, November 1974, pp. 1291-

1330.

421

of research at the Institution for Atmospheric Physics. Although there

was a clear historical interest in hail control technology, the actual

hail suppression program had only recently begun and appeared mod-

est to the visitors. The academy's suppression experiments were con-

ducted in Shansi Province and had been underway for 2 years in 1974.

Lacking an organized raingage or hailpad network, evaluation of

seeding operations is through after-the-fact ground surveys and inter-

views to estimate hail size, concentration, and crop damage. Seeding

criteria are based on visual and radar observations. 45

A program involving the seeding of warm cumulus clouds in

Hunan Province of southern China is being conducted by the Research

Institute of the Central Meteorological Bureau. Intended to increase

rainfall during arid summers, this project had been in progress for

about 5 years. Seeding was done with pulverized salt, released near

the cloud base from aircraft. Although the project was not random-

ized, there was an attempt to evaluate seeding efforts through visual

observation, by examination of raindrop spectra, and by comparison of

rainfall in adjacent regions. This work was purported to be "promis-

ing.*' 46

There had also been some dry ice seeding experiments during the

spring in the cold clouds in northern and northwestern China. The

sparse raingage network impeded evaluation in the mountainous re-

gions, and the program was discontinued because results were not en-

couraging. Research using ground-based silver iodide burners was

also suspended because of the conviction that the seeding material had

not reached the clouds. 47

KENYA

Kenya, about 130 miles northwest of Nairobi. The target areas, cov-

ering about 45,000 acres where select tea is grown, are shown in figure

4. The seeding program, supported through 1975 by private tea com-

panies, employed aircraft for dispensing silver iodide at the base of the

clouds. More than 5,700 individual cumulus cloud cells were seeded

during this period, with an average reduction in damage to tea of

about 40 percent, based on comparisons of hail damage from seeded

and nonseeded cloud systems. 48

45 Ibid.

46 Ibid., p. 1313.

47 Ibid.

48 Henderson, Thomas J.. "The Kenya Hall Supression Program," the Journal of Weather

Modification, vol. 7, No. 1, April 1975, p. 192.

422

Figure 4. — Location of target areas in the Kenya Hall Suppression Program.

REPUBLIC OF SOUTH AFRICA

South African crops suffer severely from hail damage. Near Nel-

spruit in the heart of the tobacco area, where citrus and vegetable

crops are also grown, there are typically 50 hail days per year. The

main hail season extends from October to March, coinciding with the

tobacco growth and harvest periods; consequently, damage to this

ultrasensitive crop is often catastrophic. 49

The Xelspruit hail suppression seeding project, conducted jointly

by the Lowveld Tobacco Cooperative and the Colorado International

Corp., completed 41/2 years of operation in May 1976, at which time

Simpson had evaluated the first 3% years of the program. Hail in the

7,000 square kilometer target area is produced by warm-based storms,

mostly of the multicell type, and seeding is performed from above,

48 Simpson, Joanne, "Report on the Hall Suppression Program at Nelsprult. Transvaal. Re-

public of South Africa." National Hall Research Experiment technical report NCAR-7100-

76/5. National Center for Atmospheric Research, Boulder, Colo., June 1976, pp. 3-5.

423

the results showed decreases of about 40 percent in damage and 20 per-

cent in severity for the seeded cases, based on a comparison with his-

torical control data, though the project is not randomized. Simpson

felt that these results should be regarded with cautious optimism and

found the program to have sufficient merit to warrant its continuation,

but with greater emphasis on evaluation. 51

RHODESIA

Experiments were conducted in Rhodesia during 1973-74 to con-

firm the effectiveness of seeding the tops of single cumulus clouds by

aircraft, using pyrotechnic cartridges, to augment rainfall. Random-

ized trials on 20 seeded and 16 nonseeded clouds resulted in average

rainfall about five times heavier for seeded cases than for nonseeded

cases. There was also evidence of less seeding effect under wet con-

ditions. 52 The experiments were continued in 1974-75, and it was sub-

sequently learned that seeding by the silver pyrotechnic method is

unsuccessful when cloud tops fail to reach a temperature level of

— 10° C. It has been concluded that economic viability of the cloud

seeding required that clouds reach at least to the —10° C level, the

— 13° C level being even more preferable. 53

INDIA

Indian scientists have continued studies of warm cloud seeding. In

with salt in 1973, there was a temperature rise from 1° to 2° C and

an increase in liquid water content before the onset of rain. The

clouds also grew in the vertical by a few thousand feet following the

seeding. These observed features were explained qualitatively by a

kind of chain reaction which involves the process of condensation and

updraft generation. 54

Further analysis of data from seeding experiments during the 1974

summer monsoon showed additional positive modification effects. Con-

clusions drawn from radar observations, in-cloud electrical measure-

ments, and microphysical observations following seeding of these

maritime warm clouds with hygroscopic particles are stated below :

1. Out of the four seeded cloud cases, two showed remarkable

increases in areal extent. In the remaining two cases, the areal echo

coverage remained nearly constant in one and decreased in the

other. The echo intensity increased in three cases and decreased in

one case. The height of the echo top increased in all the four cases.

Such features were not noticed in the echoes from the control

clouds.

50 Ibid., p. i.

51 Ibid.

52 McNaughton. D. L., "Seeding Single Clouds Using Pyrotechnic Cartridges, 1973-74,"

the Journal of Weather Modification, vol. 7, No. 1, April 1975. pp. 4. 14-15.

33 McNaujrhton. D. L.. "Cloud Seeding Experimental Program in Rhodesia: 1974-75," the

Journal of Weather Modification, vol. 9. No. 1. April 1977, pp. 89-90.

°* Ramaehandra Murty, A. S., A. M. Selvam. and Bh. v. Ramana Murtv. Dvnamic Effects

of Salt Seeding: in Warm Cumulus Clouds. The Journal of Weather Modification, vol. 7,

No. 1, April 1975, p. 36.

424

2. The in-cloud temperature showed an increase of 0.8° C fol-

' 3. The median volume diameter of the cloud droplets and the

cloud liquid water content showed increases in the subsequent

traverses compared to the initial traverses made in the seeded

clouds.

4. The vertical electric field in the cloud, a few hundred meters

above the cloud base, was initially negative and showed sign re-

versal before the onset of precipitation in seeded clouds. The sign

reversal may be attributed to the transport of positive charges

from the higher levels to the low T er levels inside the cloud by the

precipitation particles which are generally formed at the higher

levels in the strong updraft regions. The electric field also showed

intensification following seeding which could be due to the in-

creased convective activity. 55

THE SWISS HAIL EXPERIMENT

In Western Europe hail suppression is conducted by commercial

firms and farmers' cooperatives on a large scale, though scientifically

proven techniques are not currently in use. Hail reduction damage

levels claimed by well-conducted commercial suppression programs

are in the range of 40 to 50 percent ; however, the value of the statis-

tical evaluation is limited due to lack of randomization in the

projects. 56

In 1976, the Swiss Federal Division of Agriculture initiated a 5-year

hail-suppression experiment, conducted by the Institute of Atmos-

pheric Physics at Zurich and the Polytechnical Institute. The purpose

of the experiment, called Grossversuch IV, is to test the translatability

of the Soviet hail suppression techniques to a site in central Europe.

Specifically, the experiment has been designed to answer the following

questions :

1. Can the Soviet rocket method be used successfully in Europe,

given the climatic, geographic, and logistic conditions there ?

2. What is the effectiveness of the Soviet method and what is

the relationship between cost and benefits which may accrue to a

given region?

The U.S.S.R. claims that their operations are 70 to 90 percent suc-

cessful in reducing hail damage ; a similar success rate in Switzerland,

taking into account the hail frequency there, should permit completion

of the experiment with statistically significant results during the

projected 5-year period. 57

The Swiss Federal Air Office has reserved a space 100,000 hectares

(1,000 km 2 ) by 8 km high in the Napf Highlands, on the northern

slopes of the Swiss Alps, for the experiment. Storms which occur in

this region mostly come from the southwest and travel to the north-

^ Chatterjee, R. N., A. S. Ramachandra Murty, K. Krishna, and Bh. B. Ramana Murty.

Radar Evaluation of the Effect of Salt Seeding on Warm Maritime Cumulus Clouds. The

Journal of Weather Modification, vol. 10. No. 1. April 1978. p. 56.

c « Federer. Bruno, W. Schmld, and A. Waldvoprel. "The Design of Grossversuch IV, a Ran-

domized Hall Suppression Experiment In Switzerland," presented at the First International

Workshop on the Measurement of Hail, Banff, Canada, Oct. 21-26. 1977, Alberta Research

Council. 1977, p. 1.

" Ibid.

425

by the Soviet Union have been employed in the seeding experiment,

following a brief training period by a Soviet expert on use of the

launching ramp. The experiment includes five launching stations and

a command post equipped with three weather radars. 58

The experiment has been underway since 1976, following, reasonably

close to the plan of attack as developed then. In addition to the Swiss

investigators, there is cooperative participation from the French and

the Italians, whose contribution is mainly in operating the hailpad

network. Beginning in the 1978 summer seeding season there will also

be U.S. participation from scientists at the National Center for Atmos-

pherical Research (NCAR). 59

58 Ibid., pp. 2-3.

58 Squires, Patrick, private communication.

CHAPTER 10

INTERNATIONAL ASPECTS OF WEATHER

MODIFICATION

(By Lois McHugh, Foreign Affairs Analyst, Foreign Affairs and National

Defense Division Congressional Research Service)

Introduction

Recent years have seen increased international awareness of the

potential benefits and possible risks of weather modification tech-

nology and increased international efforts to control such activities.

The major efforts of the international community in this area are to

encourage and maintain the high level of cooperation which current-

ly exists in weather reporting and research and to insure that man's

new abilities will be used for peaceful purposes rather than as weap-

ons of war. This two sided approach is evident in the activities of the

United States which has strongly encouraged and supported coopera-

tive efforts to gain knowledge of the weather and at the same time has

endeavored to restrict the use of this knowledge to peaceful purposes

through the adoption of international agreements.

Weather research and reporting has long been one of the areas hav-

ing the closest international cooperation. Because of the global nature

of weather systems, making the prediction of weather in one area de-

pendent on reported weather in other parts of the world, cooperation

and exchange of information and techniques of weather research and

reporting are necessities. This cooperation transcends ideological

differences and hostilities.

International cooperation in the exchange of ideas on and methods

of weather modification has also been extensive. Many well attended

international conferences as well as more informal exchanges of scien-

tists and research documents have given nations the opportunity to

expand their own knowledge of weather modification. More recently,

pressures of world population and food shortages, drought, and the

continuing devastation of natural disasters such as earthquakes,

floods, and tropical storms have made the development of weather

modification abilities more critical to nations. The increasing interest

in, and the developing technology relating to man's ability to affect

rainfall, prevent hail, and curb the damage of tropical storms foresees

a, time when it will be essential that the effects of such activities on the

world's weather system be understood and any adverse effects of such

modification be controlled. As with many other scientific areas, the

problems arising out of use and experimentation with weather modi-

fication techniques are not just scientific problems, but political prob-

lems. Although the technology to use weather modification, as well

(427)

428

ogy is, are still in the early stages of development, attempts to modify

weather conditions are being made by commercial firms and by gov-

ernments. Thus, with or without a scientific assurance of success,

weather modification has become a source of controversy between

nations.

The increased activity in weather modification world wide has also

resulted in increasing complaints of perceived or potential damage to

the environment both domestically and internationally. For example,

during 1975, at a time when the U.S. Government was supporting re-

search activities to modify the strength of hurricanes, although not

actually seeding any hurricanes, Hurricane Fifi devastated Honduras.

There were several claims at the time, both in domestic and interna-

tional news media that the hurricane was either purposely, or at least

inadvertently, directed at Honduras. More recently, Project Storm-

fury, a U.S. sponsored research program into tropical storm control,

has been forced to limit its areas of experimentation because two of the

countries potentially affected by experimentation in the western Pacific,

the People's Republic of China, and Japan, objected to experimentation

near them, although other nations in the same area welcomed such ac-

tivities. Although the United States is ready to resume experimenta-

tion, recent statements indicate that the Carter administration wants

to look into the liability problem before resuming any actual modifica-

tion activities. The international community has also been troubled by

the issue of liability. In November 1975 the World Meteorological

Organization (WMO) and the United Nations environment program

held a 4-day meeting to discuss, among other issues, the possible lia-

bility of WMO and the other participants in the worldwide precipita-

tion enhancement program which was beginning in response to the

Stockholm Conference on the Human Environment. 1

In addition to the problems of damage to countries by commercial or

experimental weather modification activities, another growing area of

concern is that weather modification will be used for hostile pur-

poses * * * that the future will bring weather warfare between na-

tions. The United States has already been involved in one such in-

stance during the Vietnam war when attempts were made to impede

traffic on the Ho Chi Minh Trail by increasing the amount of rainfall

during the monsoon season. After initial public denials of such activi-

ties, former Secretary of Defense Laird, acknowledged that such ac-

tivities had taken place during 1967 and 1968. This information was

contained in a classified letter to the Senate Foreign Relations Com-

mittee in January 1974, and made public later in 1974. Having the

capability to cause natural disasters will further blur the line between

conventional and unconventional warfare and increase the risk to

civilian populations, who would be caught in the same natural disaster

as the enemy army. Additionally, if weather modification techniques

are developed by nations without corresponding understanding or

concern for the world weather system., widespread, and conceivably