[摘　　要]：

The characteristics of initial leader of triggered lightning flashes are studied by use of a highspeed digital camera system with the rate of 1000 frame per second and simultaneous measurements of current and electric field change with 0.1 μs time resolution. The results show that the altitude-triggered lightning was initiated by bidirectional propagation leader because of "current interruption" by air gap,whereas the grounded-triggered one was not. The onset of downward-moving positive leader was prior to that of the upward-going n......更多

The characteristics of initial leader of triggered lightning flashes are studied by use of a highspeed digital camera system with the rate of 1000 frame per second and simultaneous measurements of current and electric field change with 0.1 μs time resolution. The results show that the altitude-triggered lightning was initiated by bidirectional propagation leader because of "current interruption" by air gap,whereas the grounded-triggered one was not. The onset of downward-moving positive leader was prior to that of the upward-going negative leader for 843 ms in an altitude-triggered lightning under the positive ambient electric field. The downward-moving leader, regardless of its polarity, would produce inhomogeneous distribution of luminosity (current) along the channel on the moment of connection to the ground.关闭