Cloud Seeding for Improving Weather in Megacities

Abstract

Some results of activities on improving weather conditions (weather protection) in megacities by cloud seeding are presented. The main tasks of the activities were to dissipate clouds and reduce or stop precipitation in the protected area during political, cultural, and sport events. In accordance to the methodological guidelines, four seeding methods are recommended depending on synoptic conditions: the dissipation of stratiform cloudiness; the initiation of premature precipitation on the windward side of the protected area by cloud seeding to form the precipitation "shadow," the intense seeding ("overseeding") of precipitation-forming clouds moving toward the protected area to reduce the efficiency of precipitation formation in them; the dissipation of deep cumulonimbus clouds by the dynamic method. To perform weather protection operations, up to 12 aircraft equipped with measuring equipment necessary for seeding, the "ground-air-ground" data communication system, and cloud seeding means were used. Liquid nitrogen, solid carbon dioxide, silver iodide, and coarse powder were used as reagents for cloud seeding. Ground-based automated weather radar systems were used to control aviation operations and to monitor the results of the seeding. The results of more than 100 large-scale operations on the creation of favorable weather conditions performed in various regions of Russia and neighboring countries indicate the efficiency of the methods and technical means of cloud seeding developed in the USSR and Russia for the artificial precipitation control.