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Old 27-06-2008, 14:19   #1
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LIGHTNING & WATER

We have all been told to get out of the water when there is lightning. What happens to the fish at the striking point? Are they not fried, because they aren't touching the ground? Or are they fried anyway?
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Old 27-06-2008, 15:38   #2
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water is the perfect ground, energy dissipates. perhaps could fry a flying fish as its leaving the water? discuss.
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Old 27-06-2008, 16:12   #3
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NASA has shown, with satellite imaging, that the oceans rarely get hit with lightning. Apparently the surface water does not heat up enough to cause the positive charge needed for lightning to occur.

Scientists know little about what happens when lightning hits water. The electrical current probably spreads in all directions, weakening as it spreads out. Since large numbers of dead fish aren't found after thunderstorms move across bodies of water, the current probably weakens in short distances.

If the lightning's energy disperses concentrically from the point of the strike, decreasing evenly as it spreads outward; then objects (fish & people) that are oriented facing towards or away from the strike point will be at greater risk. In these cases the current would travel the length of the body, and through the heart. Likewise, objects that are further away (vertically or horizontally) from the strike would be safer.

Don MacGorman, a physicist at the National Severe Storms Laboratory in Norman, Oklahoma, says that as long as the fish are underwater, they're probably okay.

"Basically lightning stays more on the surface of the water rather than penetrating it. That's because water is a reasonably good conductor, and a good conductor keeps most of the current on the surface."
So, when lightning hits the water, the current zips across the surface in all directions. And if you're swimming anywhere in the vicinity, it'll probably hit you.
But below the surface, most of the electricity is instantly neutralized. So the fish are generally spared.
Of course, if the fish happen to be surfacing, they're at risk just like you are. And Dr. MacGorman adds that some electricity does penetrate the water, right at the strike point. “
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Old 27-06-2008, 17:11   #4
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Lightning and Diving
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Old 27-06-2008, 18:10   #5
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If caught at sea in a thunderstorm:
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Old 28-06-2008, 01:21   #6
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I imagine is a fish were within the "strike zone" it may get zapped. Energy dissipates at a rate that can be calculated using the "Inverse squared law". However, it also depends on the conductive ability of the water being uniform. If a fish is within an area that the voltage is high enough, it will be stunned, killed or maybe ready cooked if it is close enough:-) A technique of stunning fish using an electric current in water from a hand operated wand like device is used by many in conservation etc here in NZ.
However, I doubt to many fish are going to be up at the surface.
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Old 28-06-2008, 20:22   #7
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As others have alluded to, if the fish are ON (or very near) the surface at the strike point, then it is probably a fried fish (poached ?).

What happens to the lightning strike after it hits the water? It seems the experts aren't sure.
I am not am expert but I will suggest the strike will follow the laws of electricity. Current will flow where a potential difference of charge exists. It isn't just trying to get to the "ground". It wants to travel from charged area to an area that is oppositely charged - sometimes one those areas is the ground

In the case of lightning, the current (the lightning bolt) will travel through ionized gas, metal, people, whatever until the two charged surfaces are equalized and the enegry is dissipated (as heat, light, sound etc).

So the question becomes "where is the area of charge in the body of water that is struck". OK I am not sure but my gut feeling is that the area of charge will be more likely be on the surface of the water rather than deeper into the water. IF SO, then the current will travel through the surface of the water rather than deeper into it.

Which seems to be the consensus of the posts so far.

Just another 2 cents worth
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Old 29-06-2008, 04:58   #8
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Who cares about the fish? I'm worried about the guy standing on the lightening rod. Of course he is very quick and lets go of the wheel as soon as a flash occurs!
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Old 29-06-2008, 06:35   #9
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To support the theory that lightning travels radially outward through the water's surface after a strike, just take a look at boats that were struck.

Note that the little holes in the hull are nearly always at or around the waterline. None usually seem to go deep down to the keel or attachment point of the keel.
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Old 29-06-2008, 13:30   #10
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There could be good reason for that in how lightning is generated in the first place. For Cloud to ground strikes, the air must be moving over the ground(water) surface to generate the potential difference. So the surface of the water is being charged. Although I had been pondering this yesterday as to, Can the water surface being water, build a charge? Maybe it doesn't need to. Maybe it just has to be the opposite to the charge being built in the cloud. Dunno.
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Old 29-06-2008, 17:11   #11
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There could be good reason for that in how lightning is generated in the first place. For Cloud to ground strikes, the air must be moving over the ground(water) surface to generate the potential difference. So the surface of the water is being charged. Although I had been pondering this yesterday as to, Can the water surface being water, build a charge? Maybe it doesn't need to. Maybe it just has to be the opposite to the charge being built in the cloud. Dunno.
Well I dunno either; however I reckon the charge has to be opposite because we are just talking electricity (static electricity on a large scale) here and one just doesn't see current flow from a positive (or negative) pole to a "netural" pole.

Considering clouds are just masses of moving water and I accept they build up a surface charge, I guess I can accept the seawater can build up a surface charge. Maybe it is surface of the water moving against the air that creates the charge and a cloud (I expect) would have a huge surface area of water given the huge number of droplets that must exist in a average thunderhead thus explaining why most strikes exist between cloud to cloud.

Reminds me of rubbing the cat's fur with the ebony rod.
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Old 29-06-2008, 17:25   #12
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"Lightning and Diving"

WRT to the USN diving manual not discussing lightning...No, that's outside the scope of the document. Navy divers are oriented toward combat situations, and the divers were largely presumed to be young strong men in their peak--and taking risks that would be acceptable in coimbat circumstances. The same risks and procedures would often be considered totally UNacceptable in a mixed, older, less fit general civilian sport diving population, which is one reason why there are so many 'other' sets of diving tables these days.

Our instructor was a genuine ww2-era frogman. What he said about lightning was what the industry said about it at that time: Get the ***** away from the water, you will be electrocuted by a nearby strike and you have no business taking those risks. OTOH if you have a combat mission to perform--you go do it, because that's combat, not sport diviing.

I'll weigh the odds are go out in almost anything if there's reason to do so and the odds look good enough. But when the gods start going FLASH! BANG! I'd rather find a nice deep cave ashore and dig into it deeper. Nuh-uh, there are some times and places it just doesn't pay to be. Sailing is generally NOT a combat mission.
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Old 29-06-2008, 23:06   #13
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Yeah well when the stuff starts going flash boom, I too wouldn't care about facts and fictions, I would get of the water quick as :-)
KaiNui reminded me of something the other night with his going up the mast in a lightning storm trick. I was on my house roof fitting an extension pole to my TV antenna to get it up higher. A dark cloud came over the valley as I was twisting the pole to get the best reception, when a bright flash and a loud boom rang out. I said "Ooookaaey" time to get down.
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Old 30-06-2008, 04:00   #14
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If you see Lightning, you are at risk.
If you hear Thunder, you are at risk.
If your hair stands on end, or your skin starts to tingle, you are at risk.


Almost all* lightning will occur within 10 miles of its parent thunderstorm, and Thunder can typically be heard as much as 10 - 15 miles distant. Using the 5 second delay rule, Lightning followed by Thunder about 50 seconds later, is within 10 miles.

* Lightning CAN strike much farther than that. Lightning detection equipment has confirmed rare bolts striking almost 50 miles away.
Local Lightning is limited by the distance to the horizon of the cloud base (altitude). That would be, typically, up to a maximum of about 20 miles.
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Old 30-06-2008, 10:02   #15
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In Florida the nooze stations have been saying THIRTY miles now. I don't know if that's to prod the slowpokes, or based on hits they've seen. But fifty...sheesh, FIFTY?!

But if your hair starts to rise, you're more than "at risk", you're already in the circuit!
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