Laserfiche WebLink
<br />ground-based seeding of many Arizona winter clouds presently appears impractical, the economy of this <br />approach and some uncertainties in the calculations argue for further field studies where actual seeding is <br />conducted. <br /> <br />In summary, the first two field efforts' for the Arizona Snowpack Augmentation Program have greatly <br />increased knowledge of winter cloud and precipitation processes over the Mogollon Rim of Arizona. The <br />key findings are that a considerable amount of excess cloud liquid water passes over the Mogollon Rim <br />without being converted into precipitation. While pronounced variability existed in time and space during <br />storm episodes, several periods were identified that were naturally inefficient ill precipitation production but <br />appeared seedable. Ground-based seeding should be feasible for the colder storms but does not initially <br />appear practical for the warmer storm periods because the cloud layers that would be reached by the silver <br />iodide plumes would not be cold enough for significant ice crystal formation. However, further ground- <br />seeding studies are recommended with convective clouds and recently developed types of silver iodide. <br />Aircraft seeding should be able to cause ice nucleation of some of the excess cloud water in both cold and <br />warm storms at such locations that additional precipitation should reach the higher elevations of the <br />Mogollon Rim. <br /> <br />It is now known that a reasonable frequency 01 seeaaOle wmter clouds exists over the Mogollon Rim of <br />Arizona with significant amounts of unused liquid water. The challenge of future work will be to quantify the <br />amount of precipitation and streamflow enhancement that cloud seeding can produce while being socially <br />beneficial and acceptable. <br />.. <br /> <br />VII <br />