عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Cyclonic weather is among the external factors that are primarily formed in areas outside the geographical territory of Iran, and as they enter Iran, they affect the climate. Cyclones are synoptic systems in which the air pressure is low, the air flow is up, and the wind ascending in north hemisphere is anticlockwise. Because of the vertical movements of the air, the emergence of cyclonic cloud, rain, and even thunder storms is possible. The purpose of this study is an examination of cyclonic activities, as well as the spatial and temporal analysis of the statistical systems during the period 2003-2004. This study used geo-potential height data, applying the peripheral circulation approach, with respect to the adjacent neighbor method with eight neighbor kernel window limit and geo-potential gradient adapted from previous studies, to identify the spin levels in 1000, 925, 850, 700, 600 and 500 Hector Pascal and their monthly, seasonal and spatial distribution. The results indicate that in all spins the cyclones have the most frequency in winter, and the distribution of their frequency is more even as compared to other seasons; the highest number of detected cyclones in 500 level Hector Pascal and the seasonal and monthly distribution of rotate in various levels are also presented.