CLOUD SEEDING AND RELATED RESEARCH IN THE USSR

The institute developed new, complex instruments and built special units, including a powerful Tesla coil to crest ions, a powerful X-ray installation, and a "fog chamber," in which fogs very similar to natural fogs could be formed under laboratory conditions. This chamber was used to study the properties of fogs by subjecting them to various types of physical effects. The instruments and units were used for studies in cloud microphysics, in which drop size and number, water content of clouds, and humidity in fogs at low temperatures were determined. Many other problems were studied, but emphasis was placed on water-vapor condensation processes and coagulation of water drops. In the latter field, the following studies are worthy of special mention: the theoretical general- izations made by V. N, Obolenskiy, V. V. Bazilevich, and others; the numerous experimental studies by Professor M. A. Aganin and others on tue establish- ment of laws for the fusion of drops and the influence of electric charges upon this fusion; the studies by V. V. Bazilevich on the coagulation of drops and the influence of ultrasonic oscillations upon coagulation; the work of V.Ya. Nikandrov on the absorption of ultrasonic oscillations by water vapor; the work of B. V. Kiryukhin and N. P. Tverskoy on the evaporation of drops, on the measurement of humidity at low temperatures, etc. Finally, we note the series of studies of the condensation of water vapor on hygroscopic substances (creation of artificial fog! and the work of Profes- sor N. N. Andreyev and Ye. S. Selezneva on the chemical analysis of precipita- tion and on thL study of condensation nuclei. This work was not limited to theoretical and laboratory studies, but was also conducted in natural clouds and fogs. For the latter purpose, well-equipped expeditions were organized and specially-equipped airplanes were used. The first experiments on throwing various solid particles and powdered ice into clouds were conducted from spe- cially equipped airplanes as early as 1940, with the participation of P. Q. Vorontsov. Unfortunately, these experiments were interrupted by the war. The experiments on throwing dry ice into clouds which have been conducted abroad recently and publicized widely in foreign press were conducted in the USSR before World War II and not without success. The union of the school of experimental meteorologists with the school of theoretical meteorologists and workers in other branches of meteorology, which was brought about by the incorporation of the Institute of Experimental Meteorology into the Main Geophysical observatory at the beginning of World War II, had a very beneficial effect and led to the extensive studies now being conducted at the Main Geophysical Observatory. The union of theory and experiment has completely justified itself and was a prerequisite for further progress. Confidential Sanitized Copy Approved for Release 2011/09/23: CIA-RDP80-00809A000700050054-5