Lightning Strikes ! or ... Does It ???

[barnakiel]

Please view and comment at will.


Mind these are very tall, very conductive masts.

https://www.youtube.com/watch?v=uIFro3uwCoI

Why not hitting ???



Why NOT hitting ?


Cheers,
b.

[leecea]

From NOAA:

Where does lightning strike?

Most, if not all, lightning flashes produced by storms start inside the cloud. If a lightning flash is going to strike ground, a channel develops downward toward the surface. When it gets less than roughly a hundred yards of the ground, objects like trees and bushes and buildings start sending up sparks to meet it. When one of the sparks connects the downward developing channel, a huge electric current surges rapidly down the channel to the object that produced the spark. Tall objects such as trees and skyscrapers are more likely than the surrounding ground to produce one of the connecting sparks and so are more likely to be struck by lightning. Mountains also make good targets. However, this does not always mean tall objects will be struck. Lightning can strike the ground in an open field even if the tree line is close by.

[donradcliffe]

Good question. Its quite scary to be out on the water with a lightning rod during near continuous lightning strikes. I'm still trying to figure out why catamarans are twice as likely to be hit by lightning as monohulls.

[sailorboy1]

Lighting travels over 10 miles to hit the ground with up 300 million volts. The distance it saves by changing course to hit a sailboat mast is nothing to it.

[dannc]

Originally Posted by donradcliffe

Good question. Its quite scary to be out on the water with a lightning rod during near continuous lightning strikes. I'm still trying to figure out why catamarans are twice as likely to be hit by lightning as monohulls.

My theory is that the longer water line of catamarans builds up the streamer charge more so than a mono hull.

[wholybee]

Originally Posted by donradcliffe

Good question. Its quite scary to be out on the water with a lightning rod during near continuous lightning strikes. I'm still trying to figure out why catamarans are twice as likely to be hit by lightning as monohulls.

I think it is quite simple. Area's with more lightning have a higher ratio of cats to monos. Area's with less lightning have more monos to cats.

I have no data to back that up, but my instinct tells me that is the case.

[wholybee]

Originally Posted by leecea

From NOAA:
Where does lightning strike?

Most, if not all, lightning flashes produced by storms start inside the cloud. If a lightning flash is going to strike ground, a channel develops downward toward the surface. When it gets less than roughly a hundred yards of the ground, objects like trees and bushes and buildings start sending up sparks to meet it. When one of the sparks connects the downward developing channel, a huge electric current surges rapidly down the channel to the object that produced the spark. Tall objects such as trees and skyscrapers are more likely than the surrounding ground to produce one of the connecting sparks and so are more likely to be struck by lightning. Mountains also make good targets. However, this does not always mean tall objects will be struck. Lightning can strike the ground in an open field even if the tree line is close by.

Because of what is explained above, there is also a certain height something needs to be before any attraction becomes significant. It's a couple hundred feet. Below that height, it is just as likely a streamer will rise from the ground to make contact. A boat mast is pretty short, so the lightning can be very close and not hit it. But a radio tower at 1000 feet will be stuck quite often and never the ground near it.

I have had lightning strike very near my boat twice. Withing 100 feet of it, and close enough to get a strong painful shock though the wheel. I am thankful lightning doesn't always strike tall objects.

[grantmc]

Originally Posted by donradcliffe

... I'm still trying to figure out why catamarans are twice as likely to be hit by lightning as monohulls.

Don hoping you might add a source to this statistic. I'd not heard this before. Thanks.

And so a data pool would allow hypothesis, perhaps, about the possibility of differences in hit rates between, say steel and plastic, aluminium and wooden boats. What about mast type construction's affect on lightening attraction?
Is there someone/some institution out there gathering data?

[wholybee]

Originally Posted by grantmc

Don hoping you might add a source to this statistic. I'd not heard this before. Thanks.

And so a data pool would allow hypothesis, perhaps, about the possibility of differences in hit rates between, say steel and plastic, aluminium and wooden boats. What about mast type construction's affect on lightening attraction?
Is there someone/some institution out there gathering data?

It is based on insurance claims, and is well reported.
https://www.boatus.com/expert-advice...n-hit-now-what

[Capt Clark]

As leecea points out….

“ If a lightning flash is going to strike ground, a channel develops downward toward the surface. When it gets less than roughly a hundred yards of the ground, objects like trees and bushes and buildings start sending up sparks to meet it. When one of the sparks connects the downward developing channel, a huge electric current surges rapidly down the channel to the object that produced the spark.”

It’s amazing to see this “meeting” with slow motion photography. I’m on a cat and my lightning prevention has been to spray the surrounding area with a fabric softener. I believe this upward flash to meet the lightning is static electricity and I want to eliminate or reduce the static electricity around me. I may be way off but it makes me & the Admiral feel better. The surface area around a cat is twice that of a mono thus having a greater chance of suffering a strike.

I’ve read sooooo many articles on lightning and their strikes to know that we know very little about why and where they strike.

[barnakiel]

Originally Posted by donradcliffe

Good question. Its quite scary to be out on the water with a lightning rod during near continuous lightning strikes. I'm still trying to figure out why catamarans are twice as likely to be hit by lightning as monohulls.

Assume the top of the mast is less of a moving target there ?


If we trust insurers data, so is the case. Cats get hit twice. I know two that did !


And when in a boatyard too !


b.

[barnakiel]

I think the point about the need to be pretty high to get intentionally hit makes plenty of sense.


We saw a lightening hit water about the distance you see in the video (from Luna Rosa boat) and we had no damage. We were the only mast in a vast flat area. And yet, the strike went into the water.


I feel better now. Much better.


btw I think if just a sideliner had gotten Luna or Emirates today, there would be immense damage to the nav equipment onboard. An eagle would have become a duck.


Happy for them noone got hurt.


b.

[GordMay]

Originally Posted by Capt Clark

As leecea points out….

“ If a lightning flash is going to strike ground, a channel develops downward ['step leaders'] toward the surface. When it gets less than roughly a hundred yards of the ground, objects like trees and bushes and buildings start sending up sparks ['streamers'] to meet it. When one of the sparks connects the downward developing channel, a huge electric current surges rapidly down the channel to the object that produced the spark.”

It’s amazing to see this “meeting” with slow motion photography. I’m on a cat and my lightning prevention has been to spray the surrounding area with a fabric softener. I believe this upward flash [streamer] to meet the lightning [step leader] is static electricity and I want to eliminate or reduce the static electricity around me. I may be way off but it makes me & the Admiral feel better...

Lightning is NOT static electricity. Static electricity [charge separation & accumulation] is the cause of lightning.
Lightning is the dynamic DISCHARGE of static electricity.
Lightning and static electricity are closely related, but different phenomena, and on a vastly different scale.
Static electricity is the buildup of electric charge on the surface of an object, while lightning is a massive discharge of static electricity, that occurs in the atmosphere.

[seandepagnier]

If all of this is true, why cant a static charge detector on the mast detect lightning before it strikes, and quickly charge the mast to a high voltage of the same polarity to repel it?

[s/v Jedi]

Originally Posted by seandepagnier

If all of this is true, why cant a static charge detector on the mast detect lightning before it strikes, and quickly charge the mast to a high voltage of the same polarity to repel it?

Exactly what static dissipators do. The problem is that half the people don’t understand the mechanism and the rest often find reason to dismiss it or install one incorrectly.

It is true that lightning can not be prevented from striking and leaders can’t be prevented from forming, but the size of the forming leader can be altered and thus the location of impact.