Analysis on Characteristics of Positive Cloud-to-Ground in Pingliang Area of Gansu
Yi Zhang, Yan Mu-hong, Cuihua Zhang, Huaibin Wang · Gaoyuan qixiang · 2003
The characteristics of positive cloud\|to\|ground(CG) in Pingliang area of Gansu province were analyzed by use of data of lightning location system and radar. The results indicated that the rise times of lightning return stroke were between 3～20 μs with 10.7 μs mean for positive CG and 8.33 μs for negative CG. The durations of return stroke were between 10～130 μs with 51 μs mean value for negative CG. While the durations of return stroke were between 10 μs～50 μs with 19.67 μs mean value for positive CG. The depth of the dip after the zero crossing was 32% for negative, and 55% for positive CG. The two peak values appeared in daily variation at 01:00 and 13:00 respectively for negative and only one peak value at 18:00 for positive CG lightning. The distribution was reverse correlation between positive and negative CG lightning. The time of hail was correspondingto that of the peak value of positive CG lightning. The occurrence of positive CG lightning was relation with the updraft and downdraft of solid hydrometeors in thunderstorm.