Step leader
From Biocrawler, the free encyclopedia.
A step leader is a path of ionization air which extends downward from a thundercloud during the initial stages of atmospheric breakdown during a lightning strike. Often, there are multiple, branching step leaders. As the step leaders form, these branches of ionized air form in a stepwise fashion, followed by a short period of inactivity, until the final step leader reaches the ground, a tall object on the ground, or a positive streamer extending upward from a ground object. At this point, the lightning strike proper begins, as an extremely large negative current flows along the path defined by the step leaders from the thundercloud into to the ground.
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