Document Type : Research Paper

Author

• Ali Baratian

Ph.D. Student of Climatology, University of Isfahan

Abstract

Humanity has long been trying to prevent rain floods and storms, and hoped to have the opportunity to control weather and atmospheric phenomena.
In recent years, there have been a great deal of discussions about artificial rain. It is supposed, or even promised, that it can be possible, irrespective of location and time, to produce the required rainfall.
This has created more hope and expectation for artificial rainfall in human society. Today, with the rapid advent of meteorological knowledge and advancements in technology of data exchange, the thought of interfering in atmospheric events has seriously entered the realms of research and experimentation. But so far, meteorologists have come to the conclusion that it is possible to make preparations for accelerating or delaying some of the effects of climate only on a small scale.
In recent decades, many efforts and research have been made to change the natural rate of condensation and precipitation processes in order to achieve goals such as artificial precipitation, mist elimination (especially at airports) and hail lightening, all of which relies on the present knowledge of human beings in the field of cloud physics. The onset of precipitation processes (solids or liquids) requires the presence of water droplets and precipitation kernels in appropriate size and sufficient quantities per unit volume.
The nuclei spray method, evaluation of fog dispersion operations at airports, roads, sports fields, etc are also utilized. In general, the technology of fertilizing clouds has been considered by the researchers in the field of climate modification in three main categories, including:
1 . Limited and temporary control of precipitation
2 . Fog dispersion
3 . Hail prevention
  Due to diversity of climatic conditions in different regions and also geographical and topographical characteristics of each region, a method with a unique fertilizer can not be introduced for all geographical areas and climatic conditions.