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<br />16 <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />l <br />I <br />I <br />I <br />I <br /> <br />(3) Utah I and II <br />The two Utah weather modification programs reported by Hill (1979) <br />were statistical experiments. They are mentioned briefly here beoause <br />of the novel use of aircraft ioing reports in the statistioal analyses <br />as an indicator of supercooled cloud liquid water content. Hill (1982a) <br />expanded this idea in a second paper. Based on icing observations <br />during 243 events, he conoluded that the magnitude of the supercooled <br />liquid water oontent is primarily related to the cross-barrier wind <br />speed. The critical cloud top temperature below which liquid water <br />would be insignificant was also related to the cross-barrier wind speed. <br />Although this type of analysis is extremely subjective, it does provide <br />a means of developing a cloud climatology with data available from <br />standard pilot reports. <br />(4) Brid2er Ran2e EXDeriments <br />The Bridger Range experiments had two strong components. a <br />statistical program (Super and Heimbach, 1983) and a program.to <br />determine the transport and dispersion of seeding material. However, <br />limited physioal measurements of cloud characteristios were colleoted on <br />some days. <br />Radar characteristics of cloud systems over Montana's Bridger Ra~e <br />in both natural and seeded situations were reported by Super et al., <br />(1972). They found that rapid temporal and spatial variations ~n <br />precipitation intensity were oommon in all oloud systems, suggesting <br />that wintertime orographic precipit~tion, even in simple airflow <br />situations. is not a quasi-steady process. These rapid variations alsp <br />made detection of seeding effects difficult with radar. However, in <br />