Figure 2
From: Two successive bidirectional leaders propagated in triggered lightning channel
Overview of the leader process before the RS4. (a) Image with arranged consecutive high-speed video frames revealing the development of stepped leader and bidirectional leaders. The time interval between two consecutive frames was 50 μs (20,000 fps); (b) variations of the height and the 2-D estimated velocity of both upward positive leader (UPL) and downward negative leader (DNL); (c) electric field change 130 m away from the rocket launcher; (d) Magnetic field 1.55 km away from the rocket launcher; There was a delay of 1.27 ms between the waveforms measured at 130 m and 1.55 km respectively. The number of frames of several high-speed video corresponding to the waveform was marked on the top of the graph.
