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[TowerTalk] lighting

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Subject: [TowerTalk] lighting
From: (Bill Nelson)
Date: Thu, 4 Jun 1998 22:03:57 -0700 (PDT)
>Well, I'm not a lightning expert, and all the talk about lightning 
>reminds me of a yiddish proverb. But the theory I've heard and understand 
>is as follows:

>A grounded conductor aloft assumes the same potential as the ground it is 
>connected to. It therefore becomes difficult for it to build up a charge 
>and make it a potential target.

Unfortunately, the charge in the cloud generates a like (but opposite
polarity) charge in the ground below it.  This charge will travel through
any conductor that is connected to the earth.  So a grounded conductor
will build up to the same potential as the earth below it.

Now, that does not mean that any discharge will be from that conductor.
It could easily be from some other conductor under the cloud - such as
a tree or power pole/line.

>An ungrounded conductor aloft assumes whatever potential it wants. If it 
>is bombarded with rain, it picks up the charge of the rain. Wind friction 
>can also generate a sizable static charge. It may pick up enough of a 
>charge to become a target.

Maybe. But any charge that builds up is going to be minute compared to
the charge that is in the earth under the cloud.

>Of course, lightning is dumb, and it doesn't understand theory - it 
>strikes where and when it wants....

Within limits, that is certainly true.  However, it WILL take the
lowest impedance path to ground.


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