Seeding Effects On Convective Clouds In The Colorado River Basin Pilot Project


  • R. D. Elliott North American Weather Consultants


This paper addresses the matter of probable seeding effects during unstable air mass conditions in the target area of the Colorado River Basin Pilot Project (1970-1975). Various reports and articles have covered the neutral/stable condition which were the intended subject for testing, but not the unstable cases which had been inadvertently seeded as well. It is shown that when the upwind sounding gave indications that convection would be shallow enough to be embedded within the orographic cloud over the barrier, seeding effects appeared to be positive. However, for those cases in which there were indications that convection would be deep enough to emerge above the orographic cloud, there were indications of a negative effect. Reference is made to convection models in an attempt to explain how such a result is possible through the action of dynamic effects, which can diminish as as enhance net precipitation.






Scientific Papers