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C-l C. THE "STATE OF THE SCIENCE" 14. Where do we stand and where might we go? * how we might go forward * Cloud seeding is nearly a third of a century old. What do the evaluations just @;iven tell us about its state as an art, a craft, or a science? We have learned much over that period. Today we do not look at weather modification of rainfall as a source of major %'s of improve- ment. Rather we look in the range 20%, 10%, 0%. We understand more about the cloud phy- sics and the cloud processes involved -- but we are still in ignorance of much that we ought to know. Our identification of some storms or times as favorable and others as unfavorable has begun to make progress by combining empirical and theoretical insights. The strongest evidence for rainfall enhancement involving the seven latest substantial experiments this 1task force has studied seems today to be that from the two Israeli experi- ments, where relatively moist air is first being lifted by hills. This specific evidence is per- suasive to some of us and at least strongly suggestive to the others; when available, the results of critical study may well lead all three of us to the belief that the Israeli experiments are con~ clusive. (No other one of the seven recently completed experiments could, we believe, lead all of us to the belief that it was conclusive,) Notice that the only continental orographic experiment in our original list, the Colorado River Basin Pilot Project,' was severely plagued by operational. problems and other diffi,culties. We do not regard its inconclusive nature as offering either serious support of, or detraction from, the earlier results of the earlier continental orographic experiments, particularly CLIMAX. (For a discussion of ongoing re-analysis of CLIMAX, see Section 45, in thl~ Appen- dix,) Why are we in this purgatory, between the heaven of conclusive success and the hell of apparent uselessnl~ss? Basically, we believe, becaust: the inherent difficulties of the situation and the well-founded need for completely anchored conclusions have not been taken seriously enough. Once a confirmatory phase gives a firm and positive answer for the efficacy of seeding elsewhere in the world (probably when conducted in a suitably limited range of weather situa- tions) we would then recommend: 1) going over all the possible weak spots in the confirmatory phase that now selems con- clusive, 2) planning an additional confirmatory phase in which the same suitability criteria and seed- ing techniques are used, and in which all these weak spots are adequately strengthened. 3) conducting that phase exactly as planned -- at the same site, if judgments are being con- servative or neutral, at a different site (but one judged very similar) if chance-taking is the style of Ilhe day. If sufficient attention is given to all the issues raised in Chapters A and D, it may be that an initial serious confirmatory phase will appear both confidently successful and almost ade- quately careful. When and if this happens, the overall picture should be reviewed very care- fully, particularly with regard to the apparent results of parallel confirmatory phases elsewhere, before the decision is made as to whether a second confirmatory phase, according to the pattern just described, is needed. /~~ /~~.