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maryjane
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APR 16, 02:08 PM
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Bark is usually 'blown' off the trunks and limbs as the energy from the strike instantaneously boils off the moisture in the vascular layers of the tree. (assuming the tree is not dormant) Steam pressure builds up in the blink of an eye and sends large chunks of bark flying quite a ways from the tree. Happens more on a rough barked tree like pines and oaks than on a smooth barked tree. This is also wht generally kills the tree, as the vascular cambium ( xylem and phloem cells) and cambium cork a bit farther inside the bark is all ruptured by steam pressure. The xylem and phloem cells are the part of the tree that transport nutrients up and down from roots to leaves and vice versa. Often, only one side of the tree will die, as the damage doesn't always involve the full circumference of the cambium layers.
(a good bit of the noise heard when lightening hits a tree is the steam explosion)[This message has been edited by maryjane (edited 04-17-2021).]
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Hudini
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APR 17, 03:25 AM
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| quote | Originally posted by blackrams:
Just for fun, ever since I learned how to do it, I have always tried to estimate the distance of lightning from my location. So, I pay attention when I see lightning and start counting the seconds to determine that distance. Just a mental game I play.
Have had quite a few thunder storms rolling through this Spring, so I've had a few interesting lightning storms to observe. Tonight, my house shook and brought me out of a dead sleep. The thunder and lightning was intense. Even the dogs were scared. Actually, I thought it was a pretty cool demonstration of Mother Nature's power.
Looking out to the back yard onto the neighbor's property a bit later, I realized why that massive sound woke me up. One of my neighbor's trees was smoldering and there wasn't much left of it. Additional and continuing lightning is what allowed me to see that tree. The tree will not survive and I got a good reminder of how powerful lightning can be. Will get my chainsaw and tractor out and help him when it quits raining.
I have been in aircraft before that were struck by lightning, a couple of times while in flight and once while the UH1 was sitting on the ground. Interesting experiences.
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My aircraft has been struck 3 times. Once in the F111 and twice in the A320. Interestingly, if my current aircraft is struck it is my fault and I will be punished. The logic is simple, if you were not flying near thunderstorms you would not have been struck. Actually running a scheduled airline that flies into areas with storms does not make a difference. “You should have diverted”
Rams: Do you have lightning rods on your house? These are absolutely required for me after witnessing a fire inside the walls of my parent’s house due to a strike on the TV antenna around 1976 ish. The lightning jumped from the antenna cable to the household wiring and lit the paneling on fire on the inside. 16 year old me was shaking like a leaf as I grabbed a pot full of water to douse the flames as they started climbing the drapes.
This is the type of damage a strike can do.
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blackrams
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APR 17, 09:57 AM
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| quote | Originally posted by Hudini:
My aircraft has been struck 3 times. Once in the F111 and twice in the A320. Interestingly, if my current aircraft is struck it is my fault and I will be punished. The logic is simple, if you were not flying near thunderstorms you would not have been struck. Actually running a scheduled airline that flies into areas with storms does not make a difference. “You should have diverted”
Rams: Do you have lightning rods on your house? These are absolutely required for me after witnessing a fire inside the walls of my parent’s house due to a strike on the TV antenna around 1976 ish. The lightning jumped from the antenna cable to the household wiring and lit the paneling on fire on the inside. 16 year old me was shaking like a leaf as I grabbed a pot full of water to douse the flames as they started climbing the drapes.
This is the type of damage a strike can do. |
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Interesting damage on those aircraft. I've not experienced that (with the exception of the UH1 that was on the ground).
No, my home does not have a lightning rod attached/installed. Looked into that and found so many differing opinions, I wasn't sure it was the way to go. Some say it's the only thing that will protect a house from a lightning strike, others say it provides a lightning rod for more frequent events, drawing strikes. It didn't lower my home insurance so, that was the deciding factor. But, we also don't have any TV antennas or other similar metal objects sticking up from the roof so....................
Anyone else have lightning rods installed on their homes?
Edited: In fact, I took steps to remove potential lightning drawing things from close to the house. Not just or really due to the threat of lightning strikes, I removed some of the trees that were close to the house. Didn't like the damn things anyway. While I'm not a tree hater (like some of our other well known members), I don't like trees that touch or over hang a structure. They always end up doing some kind of damage even if that's just clogging up gutters or busting foundations.
Rams[This message has been edited by blackrams (edited 04-17-2021).]
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cliffw
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APR 17, 03:38 PM
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| quote | Originally posted by blackrams:
Dang!!
... what did you do to make you wife that mad ...
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Let me count the ways.
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OldsFiero
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APR 17, 06:20 PM
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We had them on the house, barn, and on the two story chicken houses on the farm. Don't know of any strikes on them. I live next door and have been hit twice in the last 40 years. Don't have lightning rods on the house or garage. The first one blew up the transformer and all three lightning arrestors on the pole. It also tripped all the breakers on one leg in the service. We think it forked and hit the TV antenna that was mounted on the lawn on a steel pole on the opposite side of the house. I say this because the flat cable from the antenna to the TV was vaporized. All that was left where the cable went across the porch and under the window was two parallel stains! The TV and VCR were the only appliances that died. The lineman said he had never seen all three arrestors blown before. We were at work at the time. The second one just roached the phone line between the last two poles. We don't know when that happened. The wire rusted in two later on.
Marc
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theogre
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APR 17, 09:21 PM
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| quote | Originally posted by Hudini:
Do you have lightning rods on your house? These are absolutely required for me after witnessing a fire inside the walls of my parent’s house due to a strike on the TV antenna around 1976 ish. The lightning jumped from the antenna cable to the household wiring and lit the paneling on fire on the inside. 16 year old me was shaking like a leaf as I grabbed a pot full of water to douse the flames as they started climbing the drapes. |
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Very Likely because antenna and wiring to it was installed wrong.
Most outdoor antennas have no earth ground from whatever mounting.
Most wiring don't have grounds either except maybe at the device(s) inside.
...Almost no-one used any protection for "flat twin wire" 300Ω for old TV's or 50Ω Coax for CB Ham and other radios.
...Mosty only "pro's" properly ground 72Ω Coax before entering a building.
Example: Cable Co's have these to ground a service before enters a home etc.
Ground wire to bottom 7/16" head bolt.
Is a ground and MoCA blocker/filter
(May have top ground point plus MoCA blocker attach to that. depend if Cable "tech" has above or just a blocker.)
Most antennas including Sat Dishes still don't have grounds from mounting hardware. So in a heavy storm the static generated alone can kill many devices. Good luck if it gets struck.
And this can happen even w/ buildings w/ lightning rods because:
Antenna at or above the rods.
Antenna is on another building or "telephone" pole.
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maryjane
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APR 18, 02:20 PM
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And most ground wiring isn't large enough to dissapate all the joules in a strike either.
My TV dish does have a gound cable, attached to the dish base on one end and a 5/8 diameter 8' long copper coat rod driven 7 1/2' into the ground. (It hit a rock or would have been driven the full 8' in)
Neither the solid core ground wire or rod will handle all of a normal lightening direct strike's energy except for the fact that the strike is of such short duration, usually less than 1 ms.
I was indirectly struck by lightening in my teen years while working on a barbed wire fence. Have no idea where (how far away) the strike actually took place as that fence was tied into others but there were plenty of steel posts elsewhere in the fences and they didn't provide enough pathway to ground to prevent me from being knocked off the fence. An average bolt of lightening releases high millions to 10 billion joules.
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blackrams
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APR 18, 02:44 PM
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I have disposed of many a cow and a horse or two that got directly stuck by lightning or were in contact with a barbed wire fence while back on the ranch. It ain't pretty and stinks to high heaven if disposal isn't done quickly.
Rams
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theogre
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APR 18, 07:32 PM
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| quote | Originally posted by maryjane:
And most ground wiring isn't large enough to dissapate all the joules in a strike either.
My TV dish does have a gound cable, attached to the dish base on one end and a 5/8 diameter 8' long copper coat rod driven 7 1/2' into the ground. (It hit a rock or would have been driven the full 8' in)
Neither the solid core ground wire or rod will handle all of a normal lightening direct strike's energy except for the fact that the strike is of such short duration, usually less than 1 ms. |
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The large ground for lightning rods often fry when hit too.
The small grounds for antennas etc dissipates the static on whatever to try to prevent them getting hit.
Quick overview of antenna grounds...
How To Ground an Outdoor TV Antenna Per NEC by Antenna Man
https://www.youtube.com/watch?v=5aey9rCC5Gs
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