Formation Features of Steps and Branches of an Upward Negative Leader

摘要

We have analyzed the high-speed video of an upward negative leader that exhibited multiple branches. From the video, which was recorded at a frame rate of 300 kiloframes per second (3.3 μs per frame), we have identified 75 leader steps, 21 being from the leader main channel and 54 from 4 branches of the leader. Through analyzing each individual leader step and branch in detail, we found a similar formation pattern for both the leader step and the branch. This pattern can be described in the following sequence: (1) the streamer area forms ahead of the leader tip, (2) the streamer area and the backward leader channel increase in luminosity, (3) the streamer area and the leader channel decrease in luminosity, (4) the streamer area reilluminates ahead of the leader tip, and (5) the reilluminated streamer area develops to a new leader tip and a new streamer area is emitted forward ahead of the new leader tip.