"w_tom" bravely wrote to "All" (07 Jul 05 22:29:12)
--- on the heady topic of " Lightning protection"

w_ From: w_tom
w_ Xref: aeinews sci.electronics.repair:52721

w_ Meanwhile TimPerry repeatedly refers to DC pulses. That
w_ would be DC analysis. Lightning pulse is AC electricity. It
w_ creates electromagnetic waves of same frequencies. You even
w_ have a chart for that frequency spectrum. What the chart does
w_ not show is how the energy content quickly tapers to zero as
w_ frequency approaches DC. That pulse called lightning is
w_ composed of electricity at RF frequencies.

He is not completely wrong, Tom. There is a phenomenon of charge
separation which takes place in the cloud and there is a DC potential.
The initial discharge starts with DC but with distance and motion we
have the effects of inductance and capacitance which establish an
impedance and results in reflections where discontinuities exist for a
moving wavefront. What we basically have is a square wave going from
one DC potential to ground but, like the Fourrier model, made up of an
infinite series of sine waves. So yes, there will be AC but the
initial natural process is all about charge separation in the clouds.
It can be no other way.

A*s*i*m*o*v

.... Power is obtained by current meeting resistance