On Fri, 06 Aug 2004 21:31:01 +0100, JPG wrote:

On Fri, 06 Aug 2004 18:22:30 GMT, (Paul C) wrote:

On Fri, 6 Aug 2004 18:36:57 +0100, Anita Evans
wrote:

I've finally fulfilled a personal ambition to get a lightning photo -
sorry to all those who have been there and done that.

Excellent.

So why doesn't lightning take the shortest route?

Probably due to fact that the air is not homogenous, with volumes of
varying resistivity, permittivity, electric field strength,
moisture/precipitation content among others. Also the lightning
discharge makes it's way from one charge concentration to another (or
to ground) in a jerky, stepwise fashion known as a stepped leader -
albeit very quickly and undetectable to the human eye. Sometimes a
single discharge is not enough to even out the charge concentrations
and further discharges will pass down the same, ionised channel. The
path taken is invariably chaotic and lightning shows that typical
chaotic "fractal" appearance.

I notice in Anita's picture evidence of slight camera movement,
showing up the "double" discharge in the upper flash. This camera
movement is used deliberately and to good effect in the following
shot:

http://www.nmt.edu/about/history/storms/image/p101.jpg


Martin


Sorry about the errant apostrophe - I felt a bit sick when I saw it as
I am always going on about the incorrect use of apostrophes.

Martin.