西北地区雷暴气候特征分析

雷电产生于中尺度对流天气系统,具有明显的局地和时效特征,对西北地区气象站点历史雷暴资料的统计发现,夏季最强,春秋次之,冬季几乎无雷暴发生;地理分布呈三大中心区;与海拔高度、经度、纬度的相关分析及年际变化分析表明,地形地势是影响该地区雷暴的主要因子.高原上的雷暴云较其它地区容易产生冰雹,冰雹日数与雷暴日数比值最大为0.36.西北夏季大部分地方的闪电密度小于1个.km-2.a-1,夏季3个月的闪电密度有3个最强中心,新疆西部是最强的闪电密度中心,超过9个.km-2.a-1,7月中心最强,6月次之,8月较弱.

Analysis on Climatic Characteristics of Thunderstorm in Northwest China

Thunderbolt is originated in middle-scale convective system and has evident spatio-temporal characteristic. According to statistically analyzing thunderstorm data from meteorological stations in northwest China, the results reveal that the most thunderstorms mainly occur in summer, secondly in spring and autumn. Few thunderstorms take place in winter.Their regional distribution shows three centers. Analysis on heights above sea level, latitude and longitude indicates that landform is the main causal factor of thunderstorms in this region. Thunderstorm clouds in plateau easily grow into hail. The maximum ratio of hail days to thunderstorm days is 0.36. CG lightning density in most northwest districts is less than 1 km-2.a-1. There are three strongest centers of lightning density in autumn. West Xinjiang is the strongest center of lightning density where it exceeds 9 km-2.a-1. The highest lightning density is in July, the second highest is in June, and the third is in August.