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Re: [TowerTalk] Lightning in the Earth

Subject: Re: [TowerTalk] Lightning in the Earth
From: Randy <>
Date: Wed, 12 Sep 2007 21:32:34 -0500
List-post: <>
I forget even what country it was in, but I've seen footage on TV of 
lightning striking a
soccer field; there was a tiny puff of dirt or grass where, presumably, 
the lightning bolt
actually hit the ground. IIRC one or more players died, but many of 
them, a goodly number
of yards from the presumed "strike", were knocked down. Obviously, 
that's no guarantee
that a strike's voltage isn't bigger than what's visible, or what's 
damaged at the point of discharge,
and I suppose you could wonder whether the affected players might have 
had voltage
induced into them rather than being shocked via the playing field, and 
there are lots of
photographs of lightning with multiple "leaders" <is that the right term 
here?> spiking off
of the main bolt, so maybe there was more than one fork of juice 
affecting them all, but
I think it's more likely just juice flowing over the ground.
Even a brand-new, solid-copper 12' rod (or anything else) can only 
dissipate X amount
of electricity, since the soil around it acts like the dielectric in a 
capacitor; there's only
so-much room for electrons, and the rest have to go somewhere else, at 
least for the tiny
fraction of a second occupied by the lightning event. I'm fairly certain 
that this is the reasoning
behind separating ground rods by 2X their length, so the electrolytic 
fields don't overlap
and waste ground rods.
So, it's not hard for me to envision the strike dissipating over poorly 
conducting soil much like
the proverbial stream of liquid landing on a flat rock. Soil is often in 
layers of different types.... 
so my mind's eye can picture a scenario where the lightning "sees" it 
easier to go sideways rather
than downwards in the ground, depending on what's below the surface, how 
well the
 (presumably very wet) surface layer conducts, etc.


Phil Camera wrote:
> lightning strike could easily travel through 50 yards of earth looking
> to equalize the earth/air voltage difference even further, and your
> equipment unfortunately, was in the way. I'm not saying it wasn't
> "induction", just that simple conduction is an alternate possibility. 
> This is plausible, except that once the energy is down in the ground, I'm not 
> sure how "far" it will conduct until it's dissipated.  Obviously would depend 
> on the conductivity of the ground.
> We do know from our Electricity 101 class, that electrical induction is a 
> proven phenomena and if a large enough voltage is applied near a conductor, a 
> current WILL be induced.
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