Personal reflections on 35 years of cloud seeding

Abstract

Thirty-five years of attempts to modify rainfall by cloud seeding in 75 countries are reviewed. The results of three recent major experiments conducted in Tasmania, Florida and Israel are discussed in some detail. The overall conclusion is that, despite all the claims to the contrary, there is little convincing evidence to suggest that it is possible to produce economically significant increases of precipitation that can be distinguished from natural fluctuations. The reasons for this are discussed in terms of recently acquired knowledge of the structure, dynamics and constitution of the major cloud systems and of the efficiency of natural precipitation mechanisms. Some possible future developments are described.