Tuesday, July 26, 2016

Ball lightning

There's an overview here, with a little footage of what may be ball lightning. Or maybe a duck got zapped; I can't see very well. Chris Drudge focuses on Wu's theory that ultra-high speed electrons can be emitted during a lightning strike, and that if narrowly contained these might produce a "microwave bubble." We've known for a while thanks to satellite detectors that thunderstorms can produce gamma rays, so somehow there's a very high energy tail--maybe from magnetic recombination when the strike collapses.
Electrons, being tiny relative to atoms, are able to pass through the metal shell of an aircraft after being accelerated outside of it via a lightning strike. Aaack! I hope this is Drudge's contribution and not Wu's. Microwaves are then emitted by the suped-up electrons inside where they form ball lightning. The electron-microwave-plasma pathway also explains the size of ball lightning, since the length of the electron bunch sped up by a lightning strike matches up with the typical 20-50 centimeter diameter of the resulting microwave bubble.

I'll be looking for the paper. Have a look at the video.


Larry Sheldon said...

I have always been pretty sure I have seen "ball lightning" in Mississippi when I was a little kid, but I thought the learned wisdom was "ain't no sucha thing."

Now it is back again.

What is the status of "sheet lightning" from the same period?

james said...

I don't know--your fiendly google says it's lightning inside (on one side?) of a bank of clouds that looks diffused. If there was a gap in the clouds and a stroke lit up one side, through the cloud it would certainly look like a sheet.

They've discovered sprites and elves with satellite photography of thunderstorms; there are probably a few other things as well.

I remember "hearing" a meteor explode above my head as I watched the sky one night on a mountain. The sound was simultaneous with the explosion--impossible, right? The thing must have been 5 miles up. But it turns out a wire fence can pick up strong radio pulses, moving just a tad, sometimes with a tiny spark jump. I don't know for sure, but ...