Poll:
Total Members Polled: 41
Discussion
Anything from three feet high to three hundred can attract a bolt.
This is a short clip of how it happens:
http://www.youtube.com/watch?v=6MUYsIjTKvk&fea...
The "stepped leader" from Cumulo Nimbus clouds is a highly charged stream of negative ions, which as it approaches the ground, attracts highly charged positive ion streams from - say - trees / aerials / umbrellas etc. When they connect, there is an "upstrike" of lightning (positive to negative) which is the lightning bolt we see.
This is a short clip of how it happens:
http://www.youtube.com/watch?v=6MUYsIjTKvk&fea...
The "stepped leader" from Cumulo Nimbus clouds is a highly charged stream of negative ions, which as it approaches the ground, attracts highly charged positive ion streams from - say - trees / aerials / umbrellas etc. When they connect, there is an "upstrike" of lightning (positive to negative) which is the lightning bolt we see.
aw51 121565 said:
The pointiest (sic) object out of that list.
I'd say this too... though it will have something to do with material as well. Pointy objects concentrate the electric field around the sharp bits and a discharge will hunt out the denser electric field.This is a cool video though:
http://www.youtube.com/watch?v=rsokWqplLLE&fea...
they are strikig large masts I presume... tall, pointy metal objects on the hillside.
Its quite interesting how there are initially two forks coming down, but when one hits ground the other sort of dies.... but then comes back to life. Then streamers start firing upwards from surrounding masts. I reckon the upward ones are because of the induced charge from the first strike. The electric field around the surrounding masts will have become very concentrated.
Unsure though because when you read about Townsend and Streamer theory of discharges I think they appear to move in different directions. Unless i remember it wrong. Going to go re-read up! Townsend theory makes sense when you read it, but then people discovered discharges that occured much faster than the order of electron migration which then kinda rules out townsend. Either way electric discharges are very peculiar phenomenon which I think very few people fully understand.
Edited by Otispunkmeyer on Wednesday 11th April 15:46
I remember watching a programme, I think it was a Horizon all about lightning.
They had this test site in (I think) South America where they had a hill with every type of lightning conductor available, and they recorded how often each one got zapped.
Apparently they couldn't find any pattern at all, the lightning would hit trees or the ground just as often as any conductor.
What they did do that was cool was to take a reel of tinned-copper wire, attach one end of it to the ground and the other to a firework rocket. During a storm they'd set the rocket off aimed at the storm cloud. The rocket would pull the wire along with it earthing the cloud, you'd get an instant lightning strike down the wire which vapourised it. It meant that they could accurately predict where and when it would strike and be able to study it. I think it has to be tested.
They had this test site in (I think) South America where they had a hill with every type of lightning conductor available, and they recorded how often each one got zapped.
Apparently they couldn't find any pattern at all, the lightning would hit trees or the ground just as often as any conductor.
What they did do that was cool was to take a reel of tinned-copper wire, attach one end of it to the ground and the other to a firework rocket. During a storm they'd set the rocket off aimed at the storm cloud. The rocket would pull the wire along with it earthing the cloud, you'd get an instant lightning strike down the wire which vapourised it. It meant that they could accurately predict where and when it would strike and be able to study it. I think it has to be tested.
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