INTRACLOUD LIGHTNING DISCHARGES IN THE LOWER PART OF THUNDERCLOUD

From analysis of observational data of thunderstorms in Gansu,China,it was deduced that the electricstructure of thunderclouds in this region is often positive charge in the upper,main negative in the middlelayer and another positive charge,large in magnitude and extensive in dimension,in the lower part.Intra-cloud discharges often take place between the main negative charge and lower positive charge instead of upper.Case analysis of 6 intracloud discharges in two storms on August 3 and 4,1986 shows that the centers of thesedischarges and the dipole moments destroyed were at the altitude of 3.8—6 km msl(7.6—-13.5℃)and 18—40 C km,respectively.     

雷暴云的电场及电荷分布模式

本文着重分析了一次强雷暴过程的地面电场和雷达回波演变特征。结果表明:平凉地区雷暴云一般为上正、中负和下正的电荷结构,强降水时在地面有强的正电场,闪电放电主要在下部正电荷区和中部负电荷区之间进行。文中提出了雷暴云的一种圆盘和圆柱状电荷分布模式,並与观测结果进行了对比。二者基本一致,尤其是能解释当降水停止或雨区移过测站时电场由正向负的急剧转变现象。     

云中闪电及云下部正电荷的初步分析

1986年夏季,我们在兰州中川机场附近对雷暴过程中的闪电进行了3站电场、电场变化及声光差的同步观测。本文定量分析了8月3日和4日两次雷暴过程中的7个云闪放电。结果表明,除一个为云中负电荷区和其上部正电荷区之间的放电外,其余都是负电荷区和云下部范围很大的正电荷区之间的放电。放电中心在海拔高度为3.8—6km之间(对应环境温度为7.6—-13.5℃),中和电矩约18—48Ckm。云下部的这种放电现象在文献中还很少见报道。