testing in other western areas and to operational applications in other mountainous areas of the west, largely by power companies; and the rain enhancement from single tropical cumulus clouds led to a major Florida experiment to learn if more sizeable areal increases in rainfall were possible by merging large tropical clouds (Simpson and Woodley, 1970, 1971; Simpson et al., 1973). Climatic studies discerned sizeable modification (increases) in summer rainfall and severe weather in and near Chicago, St. Louis, Washington, Houston, New Orleans, and other cities, all apparently due to urban releases of aerosols and heat. Results also showed that rain is not decreased nor increased measurably beyond the local urban increases, suggesting the persistent fears of "robbing Peter to pay Paul" about rainmaking may not be true.

Although predictable modification of the cloud types critical in rain and severe weather production in the non-mountainous areas of the United States has not been attained, these recent urban discoveries plus the accomplishments for modifying cold fog, mountain snow, and rain from tropical cumulus clouds, provided a reasonable foundation for expectations for eventual modification of other clouds. These expectations, coupled with growing problems that weather modification could address, including our food, fibre, and energy needs, would seem to have provided the rationale for sustained, if not increased, weather modification research efforts (Braham and Squires, 1974).

The predictable modification of the cumulus cloud and its most awesome off-spring, the thunderstorm, remains unresolved, although the urban results gave new hope that it could be done. Thunderstorm modification is sought because they produce more than 50% of the rain and most of the severe local weather in the eastern 2/3 of the United States. Recent findings from experiments attempting to enhance rain from cumulus clouds and thunderstorms reveal a range from 30% decreases in Arizona and Missouri to 25% increases in South Dakota and North Dakota (Battan and Kassander, 1967; Braham and Flueck, 1970; Dennis and Schock, 1971; Miller and Cain, 1973; Grant et al., 1974). Modification apparently was occurring in these experiments but the causes were not well understood. Growing belief in the possibility of suppressing hail from thunderstorms led to a national experiment dedicated to evaluating that possibility.

Clearly the predictable modification of the cumulus cloud and its occasional product, the thunderstorm, appears to be a central goal of the modification research of the future (Changnon et al., 1974). However, because the cumulus cloud is very complex internally, and highly variable in time and space, its organizational arrays vary widely. Its study and modification obviously require patience and a variety of sophisticated measurement tools and evaluation techniques. To this end, major steps forward were being made in the past few years to develop the models and techniques needed to research the

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cumulus cloud so as to learn how to modify it on a predictable basis.

Rapid advances in understanding the microphysical and dynamical processes in clouds led to advances in their conceptual and numerical modeling. Such models have been used in ascertaining the seeding potential over an area before a project, and on a daily operational basis they are often used as an important forecast tool in most experiments. Their use in evaluating the results of a project is just emerging.

Long-desired new instrumentation useful in furthering weather modification research was developed. Computers for numerical modeling and also for incorporation with weather radar systems led to important advances for making real-time operational decisions as to when and where to attempt modification. New weather radars capable of measuring rain, hail, and liquid water in clouds and new Doppler radars capable of measuring airflow into clouds have led to new knowledge of cloud processes allowing better evaluation of seeding (National Center for Atmospheric Research, 1973). An armored jet aircraft was developed for penetrating and studying severe hailstorms in the National Hail Research Experiment (NHRE) (Sand and Schleusener, 1974). Advances in aircraft-mounted sensors have allowed better assessment of critical conditions such as cloud droplets, liquid water content, and condensation nuclei, all needed in evaluating the susceptibility of clouds to modification.

Seeding materials and systems to deliver them have both improved markedly. Pyrotechnic flares with higher output rates of more uniform seeding materials, and other seeding devices that could be dropped into storms from high flying aircraft both served to insure more effective seeding rates in critical storm zones. A major finding showed that seeded convective clouds, especially those in a complex multi-storm system, exchanged seeding material with other adjacent major clouds on the scale of up to 65 km in space and 60 min in time (Summers, 1972; Gatz, 1974).

Research in a most critical area, the design and evalua tion of cloud modification projects, made great strides due to the more skillful use of statistical techniques, increasing physical knowledge of the clouds, and more knowledge of natural variability (Simpson, 1973; Flueck, 1973; Changnon, 1974). This increased knowledge and improved forecasting have led to reductions in the time needed to detect results of experiments, always a major problem in weather modification experiments. For example, there has been increasing use of the individual and paired cloud approaches which rely heavily on numerical and physical models for evaluation.

The 1969-73 period marked the initiation, largely through National Science Foundation (NSF) support, of serious, comprehensive research into the social, legal, economic, and ecological ramifications of weather modification (Frazier, 1970; Taubenfeld, 1970; Sewell, 1973; Haas, 1973). In particular, in-depth studies were conducted on the agricultural impacts of potential rain

augmentation and hail suppression. This new emphasis heralded the fact that weather modification was at or approaching a believable technological level. The National Oceanic and Atmospheric Administration (NOAA), under the auspices of a new 1972 federal law, began the function of maintaining records of all private (nonfederal) weather modification activities in the United States, and in 1973 this was expanded to include federal projects. New, in-depth state laws regarding permissivecontrol of weather modification were passed in Colorado, Illinois, and Texas.

Figure 1 shows where weather modification has occurred in the world during the past 28 years. Most developed nations have employed some weather modification, and during recent years many weather modification projects have been initiated in new areas. In the United States during 1973 more than 375 000 km2 experienced weather modification (Charak and DiGiulian, 1974), and more than two-thirds of Utah and South Dakota were being operationally seeded during periods of 1973. Hail suppression projects were initiated in several nations in Africa and Europe and even in Japan. The Soviet Union continued to expand their hail suppression programs so that there are now 11 projects in operation encompassing more than 42 000 km2. The Soviet program also has

involved extensive research in fog, rain, and snow management (Battan, 1973). American companies have also reported on successful hail suppression in two parts of Africa, and there has been a growth of operational hail suppression projects in the United States supported by local funds in Texas and South Dakota (Henderson, 1970; Williams, 1972; Sierra Res. Corp., 1972; Henderson and Changnon, 1972).

The growth in weather modification activity around the world was, to a degree, brought about by American weather modification firms. For instance, American firms earned $4.3 million in 1972 through foreign weather modification research and operations (Changnon, 1973). About 50% of their total income from non-federal sources in 1972 came from foreign sources. In addition, the federal agencies, particularly the Navy, exported weather modification to several foreign nations including Panama, the Philippines, and Portugal during the recent years (St. Amand et al., 1971; Gosnell, 1973).

The considerable activity in weather modification during the past five years is further illustrated by the several new large-scale programs planned and initiated. The successful results from the experimental work on orographic clouds in Colorado (Grant et al., 1968) led the Bureau of Reclamation to design and initiate in 1970

the Colorado River Basin Pilot Project to enhance snow in the San Juan Mountains in southwestern Colorado (Bureau of Reclamation, 1971; Kahan, 1972).

The National Science Foundation launched the 5-year National Hail Research Experiment (NHRE) in 1972 (NCAR, 1973). This large-scale program in northeastern Colorado is attempting to establish the feasibility of suppressing hail damage in the High Plains where hail is a major problem (Changnon, 1972).

Another recent major federally supported program in southern Florida has been supported by NOAA. This carefully designed experimental effort has shown clear evidence of rain increases from single tropical clouds and recently became a more complex project dealing with rain enhancement in multi-cloud systems through dynamic processes (Simpson et al., 1973). The success of that project partially led or forced, depending on one's view, federal agencies to attempt rain enhancement during 1971 droughts in Florida, Texas, and Oklahoma.

Another significant new weather modification program was the initiation by the state of South Dakota of a "statewide" program in 1972 (Williams, 1973). This project was unique because of its breadth and dependence on local and state financial support. It was aimed at precipitation enhancement and hail suppression. The METROMEX program, which began in St. Louis in 1971, was another major undertaking, and although oriented to the study of inadvertent precipitation modification, it has had an impact upon planned weather modification programs (Semonin and Changnon, 1974).

NOAA began in 1972 to plan for a large project to study precipitation modification in the High Plains, and after maneuvers by federal agencies and OMB, this program was shifted in 1973 to the Bureau of Reclamation. The preliminary field testing for the High Plains Project will be initiated during 1974. It appears that the final project will concentrate on test areas in Texas, Kansas, and Montana.

The $77 million spent by the federal government on weather modification in the 5-year period ending in FY73 resulted in major scientific and technical advances in weather modification. Whether these advances are commensurate with the amount of support is impossible to evaluate, but it is reasonable to say that the advances of the past 5 years outstrip those of any prior 5 years of activity in weather modification.

3. Weather modification recommendations

A variety of organizations, societies, and governmental entities has in recent years made various recommendations regarding future weather modification efforts. These were usually tied to national goals which were defined as either those interpreted by mission-oriented agency, or those identified by some august scientific group. I believe that the recommendations, which were all generally quite positive toward weather modification, were based largely on the many achievements that have been occurring during the past 5 to 7 years. Certain

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recommendations of recent vintage are presented to illustrate their content and tone.

A task force, under the auspices of the Department of Agriculture and State Universities, in 1968 made a wide ranging series of recommendations for a national program of weather modification research with specific reference to agriculture and forestry (Joint Task Force, 1968). Specific programs were recommended on 1) the direct modification of certain weather (rain, hail, lightning, and wind); 2) the study of biological and hydrological consequences of weather modification; 3) the economic and social aspects of weather and modification; and 4) decision-making in weather modification. Recommendations called for a $9.8 million effort in FY72, increasing to a $21.2 million effort in FY77.

A 1971 review of precipitation modification was performed by the National Water Commission (1971). Although the report painted a rather realistic and cautious picture of the capability of precipitation enhancement to make any major contributions to the nation's water supply in the foreseeable future, it did include as a major recommendation that "research on precipitation modification should continue, and future research should concentrate on establishing increases in runoff through drought periods." Studies of ecological and legal problems relating to precipitation modification were also recommended.

Two other reports in 1971 made major recommendations regarding weather modification. The National Academy of Sciences, after reviewing the atmospheric sciences, assigned priorities for concern and study (Committee on Atmospheric Sciences, 1971). The field of weather modification was given the third highest priority following weather prediction and air pollution. The weather modification recommendations focused on the establishment of a national program of weather modification. There were six recommendations, three addressed to federal government responsibilities and three addressed to science and technology aspects. The recommendations regarding the government included 1) the public issues should be lodged with the Executive Office of the President, 2) an unspecified single agency should be responsible for a national program in weather modification, and 3) the government should present to the United Nations a resolution concerning peaceful utiliza. tion and management of weather modification on an international basis. The scientific recommendations included 1) establishing a global climate monitoring network, 2) assigning, to a national laboratory, the responsibility and resources for developing broad levels of capabilities for weather modification, and 3) enhanced research efforts in cloud physics.

The Interdepartmental Committee for Atmospheric Sciences (1971), which has representatives from all federal agencies with atmospheric programs, also reported on weather modification. The major recommendation concerned the approach to attaining well-defined national objectives in weather modification; each objec

Bulletin American Meteorological Society

tive was identified as a national project with lead federal agencies identified with each program. The national projects and agencies recommended included a snow enhancement project (Bureau of Reclamation), hurricane project (NOAA), a lightning suppression project (Forest Service), cumulus (rain enhancement) modification project (NOAA), hail-suppression experiment (NSF), Great Lakes snow redistribution project (NOAA), and a national fog modification project (FAA). In 1972, in its first annual report to the President and Congress, the National Advisory Committee on Oceans and Atmospheres (1972), or NACOA, made five major recommendations for action. First, NACOA pointed to the various needs for legislation to protect our citizens and to regulate weather modification within a framework of beneficial use of modification. Second, they called for hastening of development of precipitation management techniques (by basic research in cloud physics, computer modeling, project design efforts, and remote sensing), and third, they called for efforts to mitigate hurricanes. Their last two recommendations concerned assessing large-scale consequences in terms of public policy and international aspects including study of inadvertent weather modification.

The American Meteorological Society (1973) recently issued a set of recommendations, largely based on the many achievements of recent years. The Society identi fied three major goals for the "national program" in weather modification, and to achieve these they made six specific recommendations regarding weather modification activities in the 1970s. These included: 1) increased development of numerical models of clouds and storm systems, 2) performance of extensive field experiments on precipitation in the major climatic zones of the United States, 3) research and field experiments concerning mitigation of severe storms, 4) expanded research on warm fog dispersion, 5) extension and expansion of facilities and expertise devoted to weather modification, and 6) increased programs to study inadvertent weather modification.

The most comprehensive recent set of recommendations relating to weather modification efforts were those issued by the National Academy of Sciences (Committee on Atmospheric Sciences, 1973). Their recommendations were centered around a choice of three national goals, all slated for completion in 1980. These goals were 1) to identify conditions for precipitation modification, 2) to develop a technology for suppression of severe storms, and 3) to establish a national and international system for study of inadvertent weather modification. Five recommendations in support of the goals included 1) more laboratory and field programs, 2) greater use of numerical modeling, 3) standardization of seeding instrumentation and agents, 4) establishment of statistical research groups, and 5) creation of a data repository for weather modification. To achieve these goals and recommendations, the Academy Panel made specific recommendations to the federal government. They

recommended 1) continued support of universities for basic research, 2) continuation of active programs by mission-oriented federal agencies, and 3) the grouping of several agency functions on weather modification planning and coordination under one agency.

An important recommendation was that NOAA be assigned the principal administrative responsibility for a national program in weather modification. They did not call for a centralization of the conduct of activities, but rather a centralization in planning and responsibility for a strong national program. The future roles of other major federal agencies with past involvement in weather modification were also considered. Their recommendation for sizeable support included a "doubling" of current efforts to reach an estimated $50 million annually for weather modification in FY75.

Review of these many recommendations since 1968 reveals certain similarities. First, all groups recommended that weather modification deserved major federal support because weather modification is high in the national interest. A well-defined national program is needed. Recommendations as to how the federal role should be shaped varied from keeping it much the same, that is, in the hands of several federal agencies, to considerable centralization under one agency.

The scientific research recommendations more nearly agreed, and all focused on the need for precipitation management, the mitigation of severe storms, and study of inadvertent weather modification. Most also recommended research of socio-economic-legal-ecological aspects. Within the context of the scientific thrust was a repeated call for centralization of the research into major laboratories to develop a "critical mass" of scientists for key research areas such as evaluation, numerical modeling, and cloud physics.

These recommendations might be judged by some to be self-serving. However, in this context, two sets of recommendations are important. One is the positive recommendation for socio-economic research and more precipitation modification research from the National Water Commission (1971). Its investigtors were not members of the meteorological community nor did they have a stake in the outcome of their investigation. The second set of recommendations without bias is that from the American Meteorological Society (1973). The professionals of the meteorological community represent as wide a spectrum of attitudes, both for and against weather modification, as exists in the nation. Thus, the Society's recommendations importantly reflect the consensus of meteorological attitudes regarding what has been accomplished and what should be done.

4. Reductions in federal support

The recent achievements in weather modification and significant recommendations for major and increased federal support of weather modification have been presented. Now, an analysis of the actual fiscal-year support of weather modification by the various federal agencies is

1 Excludes DOD spending for weather modification operations in Southeast Asia.

Includes Transportation, Agriculture, EPA, and NASA. shown in Table 1. These totals include support for research into inadvertent as well as planned weather modification, and in the last four fiscal years support for inadvertent modification research has been rather constant at about $2.5 million. The support grew from $3 million in FY63 to $19.4 million in FY72 (Committee on Atmospheric Sciences, 1973; ICAS, 1973; Lavoie, 1974 1). These totals do not include the DOD expenditures of $21.6 million for weather modification operations in Southeast Asia during 1966-1972 (Shapley, 1974). Support doubled during the 5-year "recent" period of rapid findings and achievements. Inspection of the budgets for the major agencies shows that "stay level" spending has existed for DOD which, along with NSF, had made relatively sizeable commitments to weather modification more than 10 years ago. Most agencies, other than DOD and Agriculture, made major funding increases in the 5 to 6 years prior to FY74.

The fluctuations in the total federal spending are also depicted in Fig. 2. The notable decrease in support in FY74 included a 30% decrease at NSF, and a near 40% decrease for Interior. Furthermore, the lack of growth to reach levels recommended by the NAS in 1966 and 1973 is quite apparent. The sizeable $8.5 million nonfederal support of weather modification in FY72 is also shown. Soviet expenditures for weather modification were estimated to be in excess of $100 million in 1973, compared with $24 million (federal and private) in the United States.

It is also interesting to compare these weather modification figures with those of the entire federal budget. For instance, the FY73 federal budget for R & D ($16.8 billion) increased by 6.5% (to $17.9 billion) in FY74. Federally-sponsored civilian research (non space and non military) was $5.2 billion in FY73 and rose to $5.8 billion in FY74, an 11.8% increase at the time weather modification dropped by 21%. Even in its rapid growth period of FY69 to FY72, weather modification was not 1 Personal correspondence.

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keeping up. Civilian research and development support in 1969 was $3.2 billion and reached $6.8 billion in FY73, a 120% increase. Conversely, weather modification increased from $10.6 to $19.3 million, or 87%.

The situation at NSF is an interesting example. The weather modification program of NSF is within the Research Applied to National Needs (RANN) program. The three major divisions of RANN, other than the Energy Division, all took cuts in their FY74 budgets to help support a $14 million increase in the Energy Division budget. The RANN Environmental Division, which includes the Weather Modification Program, took an average 24% cut, but weather modification budget went from $5.7 million in FY73 to $4.0 million, a 31% cut. In contrast, the Atmospheric Sciences Section of NSF had a budget for FY74 that represented a 6% increase over FY73. A proposed increase in NOAA's budget from $4.4 million in FY73 to $12.8 million in FY74 never occurred (NOAA Week, 1973). Clearly, the support for weather modification in most federal agencies was severely reduced in FY74. The support cannot approach the magnitude of growth that some agencies and most of the recommendations have called for during the 1970s unless some drastic rejuvenation occurs. The factors that led to the less than recommended growth after FY72, then to a serious reduction in FY74, and to the lack of recovery in FY75 are explored next.

5. Apparent causes for reduction in federal support The immediate reasons for decreased federal interest and support of weather modification could be ascribed to several issues or pressures, some of which are external to the specific weather modification field. These "external