PART V — SEVERE STORMS 



provides a valid basis for initiating 

 programs for application of current 

 technology to hail prevention. 



Requirements for Scientific 

 Activity 



Instrumentation — Current hail-re- 

 search plans call for a substantial 

 effort to develop sophisticated instru- 

 mentation to attempt to obtain the 

 detailed life history of hail-bearing 

 clouds. This is considered necessary 

 to create a complete physical model 

 of such storms. Development of the 

 instrumentation for this task will 

 require a major effort. The NHRE 

 five-year program involves large ex- 

 penditures for radars, specialized air- 

 craft, and large numbers of field 

 personnel. 



The instrumentation and equip- 

 ment required for a more modest 

 effort at suppressing hail in a pre- 

 designated target area would be less. 

 Such an approach could provide a 

 means of testing various hail-suppres- 

 sion techniques, would provide a 

 basis for attaining knowledge to an- 

 swer extant scientific questions, and 

 would also partially satisfy the view 

 that attempts should be made to 

 apply current technology without fur- 

 ther delay for scientific investigation, 

 which should continue concurrently. 



Applied Technology — Develop- 

 ment of hail-suppression technology 

 involves not only basic research, as 

 is being planned under the current 

 NHRE effort, but also efforts to 

 apply the technology. Needs for 

 basic research on hail appear to be 

 covered adequately in present plans 

 for NHRE. However, efforts in the 

 development and application of hail- 

 suppression technology are badly 

 needed. 



An advantage of having several 

 applications projects under way si- 

 multaneously is that they can provide 

 additional testing opportunities and 

 opportunities for learning. An essen- 

 tial requirement for optimum learning 

 is to have a number of untreated 

 cases, randomly selected, reserved as 

 "control" cases. In several locations, 

 local groups primarily concerned 

 with applications and benefits from 

 weather modification projects have 

 agreed voluntarily to forgo treat- 

 ment of a limited number of storm 

 situations to provide such control 

 cases. This willingness sets the stage 

 for an opportunity for increased 

 learning. 



However, local groups that have 

 organized to apply hail-suppression 

 technology have sometimes expressed 

 the opinion that the scientific com- 

 munity is more interested in perpetual 



programs of research than it is in ap- 

 plication. Such groups may be in- 

 clined to proceed on their own with 

 premature operational programs that 

 involve not only improper techniques 

 but also foreclose future opportuni- 

 ties for associated research efforts. 

 It is, therefore, rather urgent that 

 steps be taken to develop mechanisms 

 for cooperation with such local 

 groups while the opportunity to re- 

 serve some untreated control cases 

 still exists. If local groups begin hail- 

 suppression programs from which 

 they believe benefits are being ob- 

 tained, the opportunity for coopera- 

 tion and continued learning will 

 disappear, since pressures will exist 

 for treatment of all cases. 



Approximate Time-Scale — If the 

 present NHRE program begins its 

 activities on schedule in 1972, it 

 should produce useful inputs to hail- 

 suppression technology within ap- 

 proximately five years. In addition, 

 if steps are taken to work with local 

 groups, useful inputs to hail-suppres- 

 sion technology can also be antici- 

 pated within three to five years of 

 the start of such programs. 



Considering the time-scale for both 

 basic research and applications pro- 

 grams, it should be possible to obtain 

 adequate knowledge to carry out hail- 

 reduction efforts economically and 

 routinely by the end of this decade. 



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