关键词: 雷电, 地闪密度, 风险区划, 德清县

Abstract:  Based on the ground lightning data from 2007 to 2010, the density map of ground lightning was drawn by a grid method. The variation of thunderstorm days was analyzed based on the corresponding data in the recent 40 years and risk division of thunder stroke disaster was estimated. The results indicate that the thunderstorm days from 1970s to 1980s are more than those in 1990s and after 2000. The thunderstorm days are in a decreasing trend from 1971 to 2000, while it is in a increasing trend after 2000. There exists thunderstorm in each month except in December, especially in July and August. The thunderstorm occurs mostly in spring and summer, then in autumn, and it is seldom in winter. The thunder and lightning often happens from 12:00 to 13:00 and from 15:00 to 16:00. By 2010, the density of ground lightning is more than 4 times per square kilometer in most areas of Deqing County. The falling areas of dense thunderstorm increases yearly, the high-density area has a diffusion trend to mountain area and the northeast towns. The falling area of thunderstorm has a close relation with topography, and the high-density area is located in the northwest mountain area with the high altitude and in the low slope foothill with the altitude of 50-200 m. The high risk areas of thunder stroke disaster are from Moganshan to Duihekou regions of Deqing County, in the junction of the north of Wukang, Luoshe and Zhongguan and in the southwest of Leidian of Deqing County.

Key words: Thunder and lightning, Ground lightning density, Risk division, Deqing County