عنوان مقاله [English]
In this research, using environment-to-circulation approach, the main synoptic systems of Effective snow in the North West of Iran have been Analyzed. First, daily data of 26 snow stations In the North West of Iran from Dey 1329 to Azar 1383 of Iran Meteorological Organization was Collected. In addition, daily mean of sea level pressure data from 1951 to 2004 was collected.. After that To determine the major systems, the correlations between clusters were determined. the day that had the highest correlation with other cluster days was Selected and analyzed As a representative day circulation pattern in the cluster. results showed that Snow in the affected Occurs under two major conditions: 1- Spread and penetration of high-pressure Siberian to This Region 2- Formation and strengthening of the Black Sea High pressure In the west of Iran. It also seems that in The second pattern When the Iceland low pressure, Black Sea High pressure, Azores high pressure and low pressure Sudan are at the height of their activity we are witnessing a heavy snow fall In this area. Consequently, with strengthening the systems mentioned, There is a significant increase in The amount of snowfall And its distribution in the studied stations.