不同电结构雷暴中的地闪特征

CHARACTERISTICS OF CLOUD-TO-GROUND FLASHES IN THUNDERSTORMS WITH DIFFERENT CHARGE STRUCTURE

对观测资料的分析表明,甘肃地区和海南岛的地闪特征具有很大差异。海南岛负地闪(P型)首次回击前的电场变化波形与国外的报道类似,而甘肃地区仅有30％左右的负地闪属P型,约70％的负地闪首次回击前的电场变化波形具有明显的云闪特征(C型负地闪)。海南岛没有发现正地闪,甘肃地区有正地闪。该两地区存在两类电结构不同的雷暴,两类雷暴中地闪放电过程及特征的很大差异,说明我国的防雷规范及措施很可能需要考虑雷暴的地区差异性。

Data analyses show that the characteristics of cloud-to-ground flashes in Gansu area quite differ from those in Hainan island. The electric field change prior to the first return stroke in a negative cloud-to-ground flash in Hainan island is similar to that reported by foreign researchers. We call this kind of flash P-type negative ground flash. Only 30 percent of negative cloud-to-ground flashes in Gansu area are P-type; the other 70 percent, whose pre-first-stroke electric field changes show distinct characteristics of intracloud discharges, are called C-type negative ground lightning. Positive cloud-to-ground flashes were not found in Hainan island, but we have a few cases in Gansu area. There are two typical types of thunderstorms with different charge structure in Gansu and Hainan. From disparity in processes and characteristics of cloud-to-ground flashes in two types of thunderstorms, it is deduced that legal requirements and protection practices against lightning in China probably need to take regional differences of thunderstorms into account.