شناخت ديناميك وضعيت جو در بارندگيهاي مناطق كوهستاني

The Dynamics of the Atmosphere Resulting in Precipitation in the Mountainous Areas

In this paper, the atmospheric conditions that influence the occurrence of rainfall in a mountainous area as well as the role of coastal mountains. and their interaction with prevailing flow, in creating the local weather, are investigated. In addition to the orographic factor which may have different elements such as shape. orientation. steepness, width, height and surface roughness, mountains may also play another role as a heat source and sometimes as a moisture source at the upper levels of the atmosphere. Some of these factors may cause initiation of convective clouds and some may cause dissipation of clouds and in general their interaction result in a variety of atmospheric behaviors relating to local precipitation. Numerical simulations are conducted here, using a mesoscale model, to examine their effects on cloud formation and rainfall. Since vertical motion is a key variable in diagnosing convections. its calculation is also descrihed.