> >> In 'normal' lightning it is a 'negatively charged downward leader' that
> >> comes out of the cloud. It progresses in 50-100m jumps as the charge
> pushes
> >> it down... Note, I said PUSHES, the ground influence on the leader
> direction
> >> is relatively small, it is the gross field gradient between the earth
> and
> >> cloud that causes the major movement groundward at about 1/3c.
> >
> > Amazing that it can accelerate and push particles close to relativistic
> speeds!
>
> the particles aren't actually moving, it's charge flowing. Just as the
> electrons in a wire don't actually move at the speed of light, though
> the EM wave does.
Actually, in this case the electrons are moving. In the leader the charge
from the cloud creates an ionized channel which allows the charge to flow
from the cloud to the end of the leader. As the charge accumulates the
electric field gradient builds up at the tip of the leader. When enough
charge is accumulated it breaks down the air and creates another 50-100m
ionized segment on the channel. it can only break down that much at a time
because as the charge moves it spreads out and eventually gets below the
point where it can support the avalanche breakdown that lets it progress.
Then it pauses while the charge travels to the tip again and the process
repeats. In an average single stroke between 4 and 5 coulombs of charge is
actually transported between the cloud and ground by the ionized channel,
that is a fair number of electrons moving through that distance.
On a previous observation, about 45% of lightning strokes are actually
single strokes, 14% are doubles, 9% triple, and in the complex ones about
17% have 5 or more return strokes.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
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