the speed of lightning

[bwanaaa]

an ultrafast camera (like the kind that photographed the early above ground a-bomb detonations) would be able to show lightning reaching down from the sky. anyone know if this has been done?

 

[RadioactiveHamzter]

It's more likely to be the other way round, lightning generally travels from the ground up into the clouds. I think it has been captured before, although they'd be hard to do since they're so unpredictable.

 

[uart]

Yes, the most common situation with ground strokes is for a relatively faint "leader" to come down from the cloud in a number of "steps", forming an ionized trail as it goes. When the "leader" stroke reaches the ground a much more massive "main stroke" follows the ionized trail from the ground back up to the cloud.

I cant remember where but I'm sure I've seen some pic'ies of it somewhere that were taken with a high speed automatic camera.

 

[Blackroot]

If you have seen a still picture of lightning, didn't that camera just do that?

 

[Shalmanese]

Generally the way to take ultrafast pictures is to put a camera with the shutter open in a completely dark room. At the appropriate time, you set off a very brief flash. Conventional shutters simply aren't fast enough to match this method. For obvious reasons, this would not work on lightning. I don't know if a conventional shutter would be fast enough.

 

[ReiAyanami]

or put one at the base of a lightning pole such as empire state's

 

[bwanaaa]

 

[bwanaaa]

The camera that photographed the abomb explosions used the fact that a magnetic field can rotate polarized light. the camera was fitted with 2 polarizers at 90 degrees to each other. in between the filters, a magnetic field was rapidly switched on and off. When off, no light would pass through the 2 filters. when the field was on, the light coming out of the first filter was rotated 90 degrees so as to align with the second filter, resulting in light transmission. Because the field could be switched on and off at intervals of around the nanosecond or picosecond scale (i forget that detail) the first images of the atomic explosion at the instant of detonation were recorded.

It looks like a white hot ball of swiss cheese with big holes. (in contrast to the bleu cheese that makes up the moon)

 

[Evadman]

There have been pictures taken. The lightning goes from the gound up. there is a famous picture of a leader arcing up about 10' from a TV antenna on a farm house. IIRC the tree nearby was hit, and the antenna was a stand alone unit.

I will find pic.

 

[lifeguard1999]

Pic

As a thuderstorm develops, negative electrical charges build up.

Positive charges build up at the ground.

Eventually the attraction grows strong enough to overcome the air's resistance to electrical flow.

Negative leaders begin zigzagging downward searching for the path of least electrical resistance. It's not very bright because so little charge flows from the cloud

As it nears the ground, positive leaders begin zigzagging upward.

When they come together, the electrical circuit is completed and discharges.

The positive charge from the ground then travels upward at about 60,000 miles per second.

Several more lightening strokes can occur over the same "circuit" in rapid progression.