Cloud modification for rain enhancement (Longtime research carried out in Moldova and Ukraine)

The paper summarizes the results of the longtime cloud modification experimental research in Moldova and Ukraine aimed at rain enhancement. The research enabled to develop a unique technology of cloud seeding that provided significant rain augmentation from clouds of different types. The basic principle of the technology lies in selecting seeding target sites within cloud systems based on data related to its structure, evolution stage, and microphysical parameters at the time of supposed seeding. It was shown that the efficiency increases considerably if the seeding is performed precisely into the layer whose microphysical characteristics are appropriate for the transformations needed for rain production, namely, crystallization of droplet water and an abrupt increase in crystal concentration by 1-2 orders of magnitude. It was also shown that violation of this principle reduces seeding efficiency to the levels that make it economically senseless.