Russia’s rain-makers

Press, 3 May 1984, Page 20

Russia’s rain-makers

By

Ivan Burtsev,

chief of the Department of the Use of

Active Effects in the National Economy, U.S.S.R. State Committee for Hydrometeorology and Environmental Control.

Experiments in the Soviet Union show that the formation of hail can be prevented, the size of hail can be reduced, and sometimes rain made to fall from clear sky. There is no guarantee of success.

containing silver iodide. The reagent is injected into clouds by special artillery shells or anti-hail rockets. The combustion of the reagent forms crystalline particles. Cloud moisture settles on them, small hail-stones are formed which melt while falling, and it is raining.

To determine hail danger, specialised meteorological radars are used. In particular, the position of showers, thunderstorms and hail is determined, the horizontal and vertical extension of clouds, the trends of their development, the direction and speed of ■ their motion.

About eight million farms in the U.S.S.R. are protected by the antihail service. Each team protects 100,000 hectares. The service is equipped with radar, and has fire emplacements situated 10 to 15 kilometres apart. Use is made of meteorological forecast and meteorological satellite data. There is another aspect — the

If the hail danger is great, it is decided when and into which part of the cloud it is necessary to introduce a reagent composition

creation of artificial rain. Experiments of this kind have been conducted in this country for a long time. Various types of clouds have been studied, and various methods of obtaining precipitation have been tested. Precipitation is increased by eight to 12 per cent and up to 30 per cent on an area ranging from several hundreds to 2000 hectares. Artificial rain has also been used to help put out forest fires in Siberia. No certain way has yet been found to cause artificial rain when and where it is needed. The main difficulty is that for success it is necessary to know clearly the weather condition on a vast territory at the given moment, and the direction of weather changes in the future. Present meteorology cannot draw such a dynamically developing picture. Scientists of several countries have pooled their efforts to carry out a vast international programme — the Project for Increasing Precipitation. The programme will last until 1987 and a testing ground has been chosen in the north-west of Spain. The main task of the programme is to obtain reliable information on the possibility of the artificial increase of precipitation over 10,000 square kilometres, and to work out appropriate recommendations for various regions of the planet. It is intended to find the answer to a particularly important question: Will effects exerted on the clouds in one place influence the precipitation level in adjacent areas? In other words, will meteorologists become “rain stealers”? The earth’s atmosphere contains about 580,000 cubic kilometres of water. Only a small fraction of this moisture — about one per cent — is contained in clouds.