stepped leader

stepped leader

[′stept ′lēd·ər]
(geophysics)
The initial streamer of a lightning discharge; an intermittently advancing column of high ion density which established the channel for subsequent return streamers and dart leaders.
References in periodicals archive ?
Electrons are released from the tip of the stepped leader, multiplying rapidly as they accelerate outward, and electrons from the last two steps in the leader strike the ground and produce the TIPPs, which then proceed directly into space.
Many rocket triggered lightning experiments have been done to study the propagation mechanism of the stepped leader [1-6].
In the Triggering Model, the Dielectric Breakdown Model (DBM) [18-20], which is a stochastic fractal model, is used to simulate the propagation of the stepped leader.
The stepped leader is an advancing column of ionization that intermittently zig-zags its way to the ground (or a zone of opposite charge in another cloud).
For an example, A the definition of the beginning of the stepped leader field variation is a common confusion among scientists.
The stepped leader and the dart leader will not be discriminated in this study.
Once the stepped leader reaches the ground, or another region of opposite charge, electric current zaps between the two points, creating the visible lightning flash with temperatures over 25,000 [degrees] Celsius.
Stepped leader After electrical charges separate in a thundercloud, a channel of ionized gas, the "stepped leader," begins to carve through the air.
Cloud-to-ground strikes occur in steps: first, a stepped leader begins a branched downward thrust to the ground, then a return stroke flashes from the ground back up the channel created by the leader.
As a negative stepped leader approaches the ground, positive charges are induced at the ground and by tall conducting features, thereby maintaining the electrical potential between leader and ground.
When the stepped leader is within 30-50 m of the ground, it makes contact with the upward streamer that is closest in space to the downward stepped leader.
In the instant before the lightning strike, stepped leaders begin working their way downward from the cloud charge in 150-foot jumps.