Guys,

Thanks for the responses. I was thinking only in terms of the the most
basic first principles of radio propagation, and now I see that that's
probably not a reasonable approach.

Making reasonable assumptions about the relative signal power in
different frequency segments of a lightning strike, and then knowing
something about the attenuative properties of moist air to those
frequency segments, could clearly work, and I don't doubt that's what
airborne lightning detection does.

Of course, now you're in a situation that requires one to know
something about lightning and something about air, but I guess that's
life!

Now I'm really curious to see a spectrogram of several lightning
strikes to see what's predictable about them!

thanks again,
-- dave j, PP-ASEL, no lightning detection on board



David Rind wrote in message ...
You can find a number of websites that can provide a better description
than I can, but the basic concept is that:

1) The intensity of most EM bursts from lightning over a range of
frequencies is such that the strength at a given frequency is
proportional to the strength at other frequencies.

2) Some frequencies suffer very little atmospheric absorption and so
give an unabsorbed measure of the strength of the lightning.

3) Some frequencies are significantly absorbed by the atmosphere.

4) By comparing the unabsorbed frequencies and the absorbed frequencies,
you can make a reasonable guess as to how much atmosphere the EM burst
traversed getting to the receiver, and so can predict how far away the
lightning was.