OK, one more try! Your example describes the cloud as already over the tower.
My "gradually and constantly bleeding off the charge" scenario takes place
before that, before the storm arrives. In my scenario, the tower area rarely
gets enough charge built up to be attractive. When the stormcloud arrives, the
area around the tower is already "discharged", maybe even to a greater degree
than other surrounding areas, so it looks less attractive to the charge in the
cloud. That's what I call a sort of "prevention", but it's really just making
the tower a less likely target.
Your scenario has the ground charge moving to a point beneath the cloud "at
will" and then discharging through the tower because it represents a shorter,
easier path. If that were true, all towers would always be an easier path, and
we'd have towers being struck every time a storm passes overhead... which we
know, from observation, doesn't happen all that much.
So, how would you account for the well-grounded tower that doesn't get hit much
if at all? I say that nothing will absolutely prevent a strike if conditions
are right.... BUT... by proper grounding methods we can both lessen the chances
for a strike and protect our stuff if and when we do get one.
Rich, KE3Q, describes a mini-version of the phenomenon remarkably well: "On a
dry winter day when you're walking on the carpet at the office and then touch
the metal drinking fountain you get a sudden static discharge, analogous to a
lightning strike (though micro). Touch something metal every few steps and the
charge cannot build up to such a size. You are discharging the buildup before
it gets so big."
Hope that helps turn on the "lightning bulb", Tom!! If not, well I tried. Keep
the faith, my friend... 73, Jerry K3BZ
----- Original Message -----
From: Tom Rauch
To: jerryc ; TowerTalk@contesting.com
Sent: Tuesday, July 06, 2004 9:52 PM
Subject: Re: [TowerTalk] Lighting
> Tom
> I may be wrong but my take on this is that many of us were
> told that structures not properly grounded would build up
static
> and be more likely to attract a strike.
Well, let's think about that.
Let's say the cloud is short a few electrons and the earth
has extra.
We magically insulate the tower so well it can't receive any
electrons from the earth. Now the tower is neutral, floating
midway between the cloud's potential and the earth's. Most
of the potential difference is between the earth and cloud.
Now we ground the tower, and since it is closer to the cloud
charges move up into the tower. Hmmm. Now the tower has the
highest field gradient to the cloud!
If a charge leaks off as corona, it is attracted towards the
cloud. Now the path is shorter!
I'm really sure this stuff that the charge bleeds off is
nonsense Jerry. Unless someone else can explain how
grounding the tower moves the tower TOWARDS the potential of
the cloud (reducing voltage gradient), or how corona leaving
the tower is magically repelled from the cloud that pulled
it up and out in the first place.
All someone has to do is explain that, and I'll see the
light!
73 Tom
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
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TowerTalk mailing list
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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TowerTalk mailing list
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http://lists.contesting.com/mailman/listinfo/towertalk
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