New lightning.

[Guest guest]

There was a program on the other night about new kinds of lightning. Some of this I have known about for some time, but this was a better explanation of this stuff than I had seen before.

The first type of lightning is positive lightning. Most lightning is indeed negative, but the positive kind does occurr. It is 10 times as strong as negative lightning, the pulse lasts longer and packs more punch. Aircraft that can shrug off a regular strike can be blown apart by a positive strike. One glider that was hit by one was blown apart and some of the metal tubes inside were crushed by the magnetic field generated by the strike.

The other kind of lightning is called a sprite. This actually propagates from the upper atmosphere about 43 miles up and comes down in a cone of filaments many times the size of mount Everest, eventually turning into a single bolt. These have been related to positive lightning and could be the cause of it. These sprites probably have the potential to knock aircraft out of the sky, even aircraft that think they are safe above the storm. Sprites also produce an infrasonic sound that can be recorded.

The other types of lightning are less well known. One of these is called a blue jet and it shoots up from the cloud tops to 40 plus miles into the atmosphere. Little is known about these since they are mostly visible only from space. Even less is known about the other 3 types that are even less common than even blue jets. More exotic types may be out there.

One interesting thing was that the sprites also have some relation to meteors entering the atmosphere. Footage from space has shown meteors entering over thunderstorms, soon to be followed by a sprite or a burst of them. Most of the data was unfortunately lost when the last space shuttle blew up on re-entry. Interestingly, a photo taken of the shuttle's re-entry over San Francisco, CA showed a purple streak forming and intersecting with the shuttle shortly before it was lost. Also, a sound similiar to a sprite, one with the power of an earthquake, was detected about that same time in the same place, though there is speculation that noise could have just been the beginning of the shuttle break-up. It could also be that the shuttle re-entered over an atmosphere with the potential to spawn a sprite. Since the Shuttle was so much larger than than the typical meteor, it is possible the full engergy of the sprite was drawn into the shuttle.

NASA hasn't been seriously studying this, however. But then what to you expect of them? In the early days they lost rockets to lightning strikes but continued to launch rockets through storm clouds anyway. They did this up until the press caught them after one expensive military payload was lost to a strike that wiped out the rocket. The NASA people acted dumbfounded that launching a 300 foot long metal tube into a thunderstorm might provoke lightning.