Characteristics of the brief but bright discharges that often occur along the trails of upward positive leaders

Abstract

Characteristics of nearly 200 brief discharges in 14 upward positive leaders have been studied. Majority of the brief discharges did not exhibit electrical current at the lightning channel bottom. As a comparison, the brief discharges have been compared with those which occurred in a downward positive CG flash. The brief discharges can be grouped into five types according to their 2D shapes. Some of the brief discharges are identified progressing at two sides and some only at one side. Typical progression speed of the brief discharges is similar to that of a negative dart-stepped leader. We suggested that the brief discharges should not be simply classified as recoil leaders.