View Full Version : Lightning and Water
08-28-2000, 10:01 AM
What happens when lightning strikes into water (fresh or saltwater)? I know that when it strikes into sand, the sand is formed into these really wierd glass shapes. In water though, where does the current go? How do the fish handle it?
::These odd questions brought about by watching lightning striking over the ocean during a recent storm::
08-28-2000, 10:07 AM
The lightning will kill any fish unlucky enough to be in the area. Not sure how large the "killing zone" is, though.
I would guess some water is turned to steam when the lightning hits; after all, lightning is pretty darn hot. But other than that, I don't think there's much effect on the water per se.
08-28-2000, 10:22 AM
Down the same lines, what happens to a boat hit by lightning? They always say you should head for shore at the first sign of lightning, but what about the boats that can't?
08-28-2000, 10:24 AM
Where does the leader come from then? On land a positive leader (I think that is what it is called) is sent up by things near the build up of negative charge. Like trees, or poles, or people.
While I'm asking about lightning, in another thread it was mentioned that a car was struck by lightning and started on fire. I have always been told that a car was one of the safest places to be during lighting storms. Is this not true?
08-28-2000, 10:50 AM
A car is a fairly safe place in a storm -- there's rubber insulation (the tires) between you and the ground. However, ANYTHING can be hit by lightning if it's exposed. So while a car is relatively safe, it's not foolproof.
08-28-2000, 10:56 AM
The function of a 'leader' when lightning strikes ocean is provided by the water -- presumably positive ions cluster around the negatively charged section of cloud, and wait for the voltage to exceed the insulating ability of the air. On land, the highest point around is the most likely to be struck, for being closest to the clouds (and thus requiring the least buildup of charge to initiate the lightning.) In the ocean, prehaps the tops of waves get close enough to the clouds to induce the discharge, or the strikes occur more randomly than on land.
As for cars, they are a good refuge from lightning, especially in a flat area. But not because they don't get struck -- rather, the metal body of the wet car is a much better conductor than your flesh, and the lightning will follow the easy path to ground instead of trying to flow through your body, which would burn you and disrupt your electrical functions. However, the heat generated by that kind of current, in combination with the heat of the ionized air that carries the lightning to the ground, might well be enough to ignite the flammable parts of an automobile, particularly if the car has not been rained on. Still, the danger of being caught in a flaming car seems more remote and less deadly than the danger of being directly hit by lightning yourself -- I personally would choose to hide in the car, despite the incendiary risk.
08-28-2000, 11:28 AM
On boats, especially larger ones, everything electrical and metal should be electrically bonded (wired), usually to the hull (on a steel boat) or a "dynaplate" (basically a big metal plate located underwater on the surface of the hull) on a fiberglass or wood boat. So, if the lightning strikes it should go through the bonding and be dissapated into the water.
If lightning strikes the water, as someone mentioned, it will dissapate pretty quickly, but I don't know the range. You're probably better off in freshwater than salt though, since salt water readily conducts electricity!
Also, you should never drive with your left hand on the wheel (car) during an electrical storm - that way when the car gets ZAPPED! by lightning, it will travel through the body of the car, up the steering column, through your RIGHT hand, and down the RIGHT side of your body, narrowly missing your heart over on the left side... :) Ha, ha, ha!
08-28-2000, 11:30 AM
By the way, that's dissIpate! Please excuse my spelling...
08-28-2000, 01:36 PM
Welcome to the SD! Thank you for posting to this thread too! But now I have to dispell an urban legend that you are helping to spread. In my reading about lightning, I have found the following from the Weather Channel at their website:
A car's rubber tires give protection from lightning.
False! Actually, the car itself is very well insulated and offers more protection than being outside in the storm. Of course, the exception to this is the convertible, which provides virtually no protection.
and this one, which I thought to be true until I read:
Lightning always strikes the tallest object.
False! Lightning strikes the best conductor on the ground, not necessarily the tallest object. In some cases, the best conductor might be a human being.
08-28-2000, 02:41 PM
Thank you for the welcome, aenea. I was actually here more than a year ago, but I changed jobs and have only recently been able to post again.
As for the rubber tires ... I'm not saying the Weather Channel is wrong. But hey, my fifth-grade science teacher explained it all to me, and Mr. Ricks was ALWAYS right.
08-28-2000, 03:56 PM
I think the dissipation of lightning in water is with the square or maybe the cube of the radius. The farther away, the more it drops off.
Regarding cars, while the tires do provide some insulation effect, with enough charge you can get a capacitance and jump the gap between the ground and the wheels. How a car protects you is that the frame and panels of the car are metal, very good conductors, and they make a sort of Farraday cage around the inside. The electricity is passed through the metal and around the interior, so the things in the interior are okay.
One other thing about boats - they often have masts or antennas sticking up. These are posts with pointed tops. Pointed tops are ideal for attracting lightning strikes. Something about the geometry and accumulating charges.
And yes, it's not always the tallest object that's hit. If you are out in the open and a lightning storm picks up, head for cover. If you feel a staticky feeling, hair standing on end and such, get down quickly - you are very seriously in danger of being hit immediately. Crouch down on your toes, and cover your face with your hands, tucking your head down. Be as low to the ground as possible while providing the smallest contact with the ground. The hands over the face are in case you are hit, the charge jumping around the outside of your body don't burn your face/eyes.
I have a friend who was hit by lightning. Well, he was a secondary hit. He was in a sleeping bag lying on the roots of the tree that was hit. He had short term memory loss (I think if finally returned), was knocked unconscious for a while, and had little scars across his body from the arcs of electricity.
08-28-2000, 04:38 PM
Originally posted by PeeWee
[B...down the RIGHT side of your body, narrowly missing your heart over on the left side... :) Ha, ha, ha! [/B]
Spreading a U.L. on SDMB. For shame! Your heart isn't symmetrical but it's in the center of your chest.
On a related note it's dangerous to work on high voltage equipment with both hands. Ground one and touch the other to a voltage source and the current passes through the heart quite disruptively even if you stand on an insulated mat. My life has been saved more than once by that habit.
08-28-2000, 04:59 PM
When I was a lad at Boy Scout camp I was standing in a lake that got hit by lightning. It was about a 5 acre lake and the lightning hit the end of the lake farthest from us. I just remember everyone suddenly standing really stiff for a second, straightening up, and then it was over, no real sensation of a shock.
08-28-2000, 06:08 PM
my 35'sailboat has a metal mast 50'above water and was recently hit by lightning. All the electronics fried, even those not connected. The discharge travelled along the most unlikely places. Luckily I was away. Unluckily, I am now dealing with the insurance to repair the damage which is abot $10,000.
08-28-2000, 06:32 PM
As far as cars and tires go, remember that the lightning has no truble at all crossing a half-mile or so of air... Why should it have any problem with a half-foot of air or rubber beneath your car?
Another common misconception about lightning: the purpose of lightning rods is not to provide a path to ground for lightning. It's actually to prevent lightning from striking in the first place. The idea is to allow the built-up charge to dissipate slowly and gently, rather than all at once in a bolt.
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