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Re: [Phys-L] lightning



On 06/13/2013 02:06 PM, Trivilino, Herman wrote:
So there's a plasma, with positive ions drifting one way and free electrons the other?

I don't know for sure, but I suspect that free electrons don't last long.
It's too easy for them to attach to molecules to form negative ions.

Temperatures inside lightning can exceed 25 kK.

Well, yes and no. The temperature is a moving target. As I understand
the original question, it pertained to a time at the end of the leader
and the very beginning of the main bolt i.e. the "return stroke", where
the temperature in the leader channel is verrrry much less than 25000 K.

After the return stroke has begun to propagate upward, you've got two
different regimes to consider.
-- Ahead of the wave front there is a relatively cold channel with a
high voltage but very little current.
-- Behind the wave front there is a much higher temperature and a much
higher current. I don't know for sure, but I suspect the voltage is
of the opposite sign and lower in magnitude.

This is one of those large-glass-half-full situations. There is a tremendous
amount that is know about lightning, and also a tremendous amount that is
unknown.

It makes a good answer to the student who asks, Why go into physics if
everything has already been figured out?