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lightning

Merry Christmas
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bgisborn

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Mike, the sense of air terminal protection is simply this. Lightning is not a supernatural force. It is an electrical phenomena. When presented with a selection of parallel circuits it will send most of its coulombs through the one offering the least impedance. That would probably be the air terminal connected to a good conductor to ground.

As for the size of the conductor to the ground rod: A given grounding system, such as a 8 foot ? inch copper rod in soil, will only take a limited charge within milliseconds, therefore, increasing the size of the conductor, below 6 AWG, to it will not have any significant effect effect. Most of the lightning's charge travels along, but not in the air terminal's conductor anyway. The enormous inductive reactance is probably responsible for this "skin effect"-but I'm guessing

When lightning hits a tree it is presented with the parallel circuits of bark, a bad conductor, and tree sap, a much better conductor. Because most of the current flows through the sap, it boils and blows the tree apart with steam pressure. High resinous hot sap will then often catch fire.

The lightning also raises the potential gradient of a concentric area around the tree. A cow standing beneath the tree will have her hind quarters at a significantly higher potential than her forelegs. She?ll be electrocuted.

The electromagnetic field surrounding the lightning plasma can cause severe damage to electronics and arcing between metal parts due to induced currents. I would therefore not be wanting to fuel a rocket with liquid hydrogen, liquid oxygen and hydrozene regardless of the available air terminals.

You gave us a great lecture. It was an honor to be taught by the world?s finest electrical instructor.
As for electricity, there are no UNIVERSAL truths. A potential difference is not always required for an electrical current. A superconducting coil is an example of current flow without potential difference. Electrical current is not always the movement of electrons. In some some electrolytes it's the movement of positively charged ions. In this case electricity does flow from positive to negative.
It is not always necessary to first complete the circuit for current to flow. The potential difference can make its own path. That gets us back to lightning-so I'm not off subject.

Bob Gisborn
 
G

Guest

Guest
Re: lightning

I am adding on to your comments with a couple of my own:

The ground rod cannot sink the whole lightning strike, but the ground rod will clean things up after the strike (static, etc.).

Additionally, there are sinks (lightning arresters) needed to grab the potential out of the ungrounded conductors.
 
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