Lightning

[yossam]

At 7000 fps....................


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

[Dune]

Never seen anything like it, great. Thanks.

[Hetzen]

I had a bet with Matt that lightning strikes from the ground up. We'd had a few drinks and was sure I saw it somewhere.

Thanks for posting, you can see the charge being pulled from the clouds to the ground and on contact the bolt rises upwards.

[Hannes]

Jon, recently I saw a documentary on the TV about lightnings, and they said, that there are lightnings that strike from the ground up, but they seem to be very rare. There was a similar movie shot at high speed.

[Hetzen]

Hey Hannes, I think what I saw was arguing that the main power event is a reaction from the ground up. Looking at that 7000fps footage, you can see ionised streaks reaching for the ground, and when it touches, the main energy spark travels up those streaks.

[PabloMack]

Interesting. It's like its searching for a ground connection. The moment one of the tendrils touches the ground then a solid path is established and the other feelers are abandoned. The moment the path is established then there is a brilliant light, presumably by the pent-up energy that suddenly has a low-resistance path to ground.

..I think what I saw was arguing that the main power event is a reaction from the ground up. Looking at that 7000fps footage, you can see ionised streaks reaching for the ground, and when it touches, the main energy spark travels up those streaks.

Yeah. The direction of ionization path travel is not necessarily the direction of electron flow which may be reverse.

[Matt]

I had a bet with Matt that lightning strikes from the ground up. We'd had a few drinks and was sure I saw it somewhere.

Thanks for posting, you can see the charge being pulled from the clouds to the ground and on contact the bolt rises upwards.

Wait, so who won? 

[Hetzen]

At the moment I think I have. What do you think Matt?

[Matt]

Doesn't the video show it striking from the top down?

[Hetzen]

The charge disparity reaches from the top down, but the equalization rises from the ground up.

If you were standing in a field with your finger in the air, and lightning struck you, it would be your foot that felt the pain before your finger.

[Matt]

Can you cite your sources? (since there's a beer in it) I suppose that equalization is too fast for the video to show?

[Hetzen]

Well if there's a beer in it, time to take this seriously

Have a look at this 1000fps footage. Particularly around 20secs. You can see over 3 or 4 frames the 'equalisation' running back up the streak.

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

[Matt]

There's a node part way up the path, at which it splits into two or more separate paths up to the cloud. At 0:21 to 0:22, on the first bright frame it appears to share the charge between at least 2 paths to the cloud, and then the very next frame it distributes the charge only toward the right path, therefore the right path brightens. Over the next few frames the brightness diminishes overall, without any relative differences along the path, as far as I can see.

EDIT: Looking again, I'm not sure  There might be more than one path touching the ground on the first bright frame.

[Hetzen]

That clip has a weird frame frate, but I grabbed 5 sequential frames. On the 2nd and 3rd I believe you can see the glow move upwards.

[Matt]

Those are the same frames I'm talking about. I don't believe it shows anything moving upward, but rather: A) frame 2 has more energy than frame 3; B) all of the energy is moving along the rightmost path to the cloud in frame 3, but shared amongst a few different paths in frame 2. But that's just my interpretation.