Simultaneous Observations of Electric Signals at 60m and 550m from Altitude-Triggered Lightning

摘要

In the summer of 2005, Five lightning flashes were successfully triggered with three classical triggering flashes and two altitude triggering flashes in China. This paper mainly presents the electric fields change of the bidirectional leader system and the dart leader-return stroke of two altitude-triggered flashes at distances of 60m and 550m from the triggering site. The electric fields changes produced by the bidirectional leader system at 60m and 550m are negative 4.7-14.6kV/m and positive 0.11-0.16 kV/m, respectively. The estimated slope coefficient of the charge distribution along lightning channel for the bidirectional leader system is (1.2-3.8)×10 k -7 C/m 2 . The dart leader-return stroke sequences appear as V-shaped pulses, the bottom of V-shape being associated with the transition from the leader to the return stroke. The electric fields changes produced by the dart leaders at 60m and 550m are 17.8 kV/m and 1.2kV/m respectively. The distance dependence of the dart leader electric fields change is r -1.18 .