The Lee Cyclogenesis Mechanism in the Zagros Mountain

The Zagros Mountains, oriented from northwest to southeast, are barriers against western winds. This study was conducted to find a mechanism for describing specific type of cyclogenesis occurrence in the Zagros leeward. Therefore, by examining six cycles in this category, it became clear that as the cycle approaches the Zagros domains, there is an interaction between the cyclogenesis system and the Zagros Mountains, which leads to the formation of a particular thermal structure. Thus, a high pressure center is formed in the Zagros Mountains in the thermal winds. Such thermal abnormalities coincide with a decrease in static stability and dragging of the atmosphere and increasing relative tensile strength in the Zagros windfall. Then, perturbation potential vortices in upper levels stay on the lower perturbation potential temperature, atmosphere heat stress increased and cyclogenesis can occur in the leeward. On the other hand, the average underlying temperature (1000-700) and upper (500-300) levels showed that the most important effect of the mountains is to alter the mean distribution of low levels of potential temperature and hence to change the baroclinic waves. In fact, the Zagros Mountains, with increased meridional gradient of the potential temperature in the lower layer of the atmosphere, cause a sharp difference acceleration between upper layer and low layer of thermal disturbances. Accordingly, the Zagros Mountains, in terms of creating changes in the tilt of in Baroclinicity waves, provide the basis for the cyclogenesis in its eastern parts. So, this kind of cyclogenesis is based on the mechanism of orographic modification of baroclinic waves.