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<br /> <br />002343 <br /> <br />. <br /> <br />. <br /> <br />original results of these projects were inconclusive but all suggested <br />increases in snowfall from seeding. <br />A considerable effort also has gone into increasing rainfall within <br />frontal systems approaching the West Coast. There is less agreement <br />among atmospheric scientists as to the success or significance of these <br />efforts. A major difficulty is that increases are reported for selected <br />bands of moisture within the storm system, and such selectivity makes <br />independent analyses of reported results much more difficult. In general,' <br />a major difficulty in analyzing many weather modification efforts is the <br />policy of reporting increases in percent of natural precipitation in sub- <br />systems within a broader precipitation type. This is particularly true <br />in reporting results of seeding of convective clouds, which will be <br />discussed later. <br /> <br />Convective Precipitation <br />Most seeding to augment snowfall is accomplished with ground based <br />silver iodide generators. On the other hand, convective clouds are <br />seeded by both ground based and aircraft based generators. The principle <br />rationale for seeding convective clouds from aircraft is that seeding can <br />increase rainfall from small convective cells, but may decrease rainfall <br />from larger systems; so it should be more selective. -Commercial operators <br />who seed from ground based generators cannot be as selective; and in this <br />respect, the two methods are contradictory. <br />The majority of atmospheric scientists feel that current technology <br />is adequate to increase rainfall from small convective clouds. However, <br />these increases, although large percentwise, may be small volumewise in <br />respect to natural, annual or seasonal rainfall. Generally, natural <br /> <br />4 <br />