Some features of lightning ground flash activities observed in tropical thunderstorms

Abstract

Some features of lightning ground flash activities in tropical thunderstorms (Sri Lanka) were studied with information provided by two lightning direction finding (DF) stations installed at Colombo (79.84 E, 6.93 N) and Ratnapura (80.43 E, 6.64 N). A total of 980 lightning ground flashes recorded in February 1999 during the inter-monsoon period were used in this analysis. The striking rate of ground flashes per hour was found to be varying from 7 to 134 with the mean of 61. The mean number of strokes per flash for negative and positive ground flashes was 3.0 and 1.2 respectively. 73% of negative ground flashes had more than one stroke per flash whereas 8.2% of positive ground flashes had more than one stroke per flash. The percentage of positive ground flashes is 6.2% of the total number of flashes.