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<br />Osborn is incorrect in saying that the Flagstaff experi.ents were <br /> <br />"based on" Weinstein's or any other model. The observations of the <br /> <br />fully randomized series of seeded and unseeded clouds stand on their <br /> <br />own feet (Weinstein and MacCready, 1969). The Weinstein model was, <br />_L <br /> <br />however, very useful in interpreting the result of the randomized exper- <br /> <br />iment. (For other recent productive uses of this model, see Danielsen, <br /> <br />et al (1972), and Hirsch (1971).) Analysis of the results of 9 days <br /> <br />when paired seed/unseed events took place showed increases in cloud <br /> <br />height averaging 5,900 feet, increases in estimated rainfall of 2 .. <br /> <br />per cloud, and increases of duration averaging 10 ainutes, each increase <br /> <br />being significant by a student's test at better than the 2 percent level. <br /> <br />The model showed predictive power significant at the 4 percent level <br /> <br />and predicted increases of 6,500 feet, 2.86 _, and 11 minutes for the <br /> <br />height, rainfall amount, and duration respectively. <br /> <br />Osborn stated that "the claims of success for the (Flagstaff) experi- <br /> <br />aents have been challenged by several investigators," and in his oral <br /> <br />presentation cOJDllented further that this experiment "was not fully ran- <br /> <br />dOJDized." These allegations were not docUJl8Jlted nor were any grounds <br /> <br />for such challenges indicated. <br /> <br />With respect to extrapolation from the single cloud seeding to wide-area <br />effects, the matter of concern is whether the seeding of an individual <br /> <br />cloud or of a group of adjacent clouds has consequences, positive or <br />negative, over a wider area than that directly affected by those clouds, <br /> <br />or over an extended downwind range. Weinstein (1972) is irrelevant to <br /> <br />12 <br />