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Author Topic: How does lightning take the path of least resistance?  (Read 8837 times)

Cold

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Cold asked the Naked Scientists:
   
I have heard about how lightning takes the path of least resistance, so it arcs from a tree to you (if you are nearby). My question is how does the lightning know that there is a less resistive path nearby? How can it sense you are nearby? Or even "calculate" if you are too far away and just go down the tree?

What do you think?
« Last Edit: 17/09/2011 12:22:12 by chris »


 

Offline yor_on

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Re: How does lightning take the path of least resistance?
« Reply #1 on: 17/09/2011 09:43:15 »
Maybe, just maybe, you can think of it as lightening having 'tasted' all paths there is, then coming to be in the path offering it 'least energy expended' to maintain. To me it's a principle of this universe, no matter how you try to explain it. When you fall you have one direction, not many, gravity doesn't offer you a countless directions, only one optimal.

And it's really weird how it does it :)
 

Offline chris

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Re: How does lightning take the path of least resistance?
« Reply #2 on: 17/09/2011 10:55:42 »
What a great question! And it's great because it made me realise that I'd never thought about this issue before.
 

Offline RD

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Re: How does lightning take the path of least resistance?
« Reply #3 on: 17/09/2011 12:10:35 »
The electric charge creates a great many paths in a tree-like structure ...


http://205.243.100.155/frames/interesting.html

http://en.wikipedia.org/wiki/Lichtenberg_figure

The lightning takes the shortest path of the many forked paths which have been created,
« Last Edit: 17/09/2011 12:36:40 by RD »
 

Offline mitch

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How does lightning take the path of least resistance?
« Reply #4 on: 17/09/2011 13:12:11 »
It's a common misconception that ALL current from a power source takes the path of least resistance. The flow that current takes are a portion of the total current inversely proportional to amount of resistance of the path.

For instance, with an electric circuit, if you take a 1megaohm resistor in parallel with a 1kiloohm resistor, most of the current will go through the 1kOhm but only 99.9% of it. My degree isn't in weather but I would venture to guess that the same applies to lightning. Most of the current goes through the path of least resistance - so much so that the rest of the current is negligible.
« Last Edit: 17/09/2011 18:16:10 by mitch »
 

Offline darwineuron

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How does lightning take the path of least resistance?
« Reply #5 on: 17/09/2011 18:23:36 »
Hey! I posted this almost exact same thing a few eons ago!
http://www.thenakedscientists.com/forum/index.php?topic=12840.0;topicseen
 

Offline Phractality

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How does lightning take the path of least resistance?
« Reply #6 on: 18/09/2011 05:36:05 »
Lightning is not DC current; it looks for the path of least IMPEDENCE, not least resistance. DC current will follow a crooked wire around sharp angles; due to its high frequency, lightning prefers to cut corners. Lightning can bypass a wire loop which has zero ohms DC resistance but billions of ohms impedence at the frequency of the lightning, jumping instead across an air gap with billions of DC ohms.

Since you never know in advance the amount of charge, capacitance and resistance, you can never predict what the lightning will do.
 

Offline Geezer

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How does lightning take the path of least resistance?
« Reply #7 on: 18/09/2011 07:06:13 »
Strictly speaking, there is no "path of least resistance". If there was, lightning would tend to follow a straight path, which it obviously does not.

Lightning creates it's own path by causing the dielectric medium (Earth's atmosphere) to breakdown and allow conduction. This requires a chemical reaction of the molecules in the atmosphere which probably has something to do with their proximity at a particular moment in time, but, as that is highly unpredictable, it's likely impossible to predict the path that the lightning will follow.

 

Offline yor_on

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How does lightning take the path of least resistance?
« Reply #8 on: 03/10/2011 01:18:41 »
Ahh, But I say it takes the path of least energy expenditure. Reading you I started to wonder if that would be the exact same as a path of least resistance, but thinking some more I suspect the definitions might differ slightly? I don't think that I am wrong anyway, and it should be testable. Why not read what this little gem says about it. It's interesting in more ways than one, as we're looking at ionized 'paths' here I mean :)


A Survey of Laser Lightning Rod Techniques.



 

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How does lightning take the path of least resistance?
« Reply #8 on: 03/10/2011 01:18:41 »

 

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