Document Type : Research Paper

Authors

• Hossein Haddadi ¹
• Hassan Heydari ²

¹ Master of Climatology, Tarbiat Modares University

² Assistant Professor, Department of Natural Geography, Urmia University

Abstract

Heavy rainfalls with thunder is an environmental phenomenon in Western part of the country. Western areas of the country are potentially prone to heavy thunder stones, since they face the direction of Western Winds and Mediterranean humidity and also because of the Zagros Elevations. Upper atmosphere data in the National Center of Environmental Prediction was used for synoptic study of the heavy rainfall on May 2^nd, 2010. The condition of atmosphere during the heavy rainfall was analyzed by computational and graphical methods. Results of the synoptic analysis indicates that factors like blocking and twist in 500, 600 and 700 hPa, instability, convection in all atmospheric levels from 500 to 1000 hPa and positive vorticity in 500, 600, 700, 850 hPa were among affective factors in the occurrence of heavy rainfall on May 2^nd 2010. According to the humidity-wind maps, the humidity resources of this heavy rainfall were located in 1000 to 850 Persian Gulf alignments and 700, 600, and 500 hPa of the Mediterranean Sea and the Red Sea.

Keywords

• synoptic
• heavy rainfall
• cyclone and anticyclone
• Ilam
• Iran

20.1001.1.25883860.1391.21.82.16.0