http://upload.wikimedia.org/wikipedia/commons/f/f8/Red_Sprite.ogv
Watch this one if you possibly can:- it is 39 seconds of video shot from the International Space Station over East Asia, and will blow your mind. Below the land is suffering thunderstorms across a large area (the tops of the cumulonimbus can be seen as grey blobs above) and, every so often, there is a bolt of lightning. The lightning bolt cannot be seen from the ISS because it is below the cloud, but the light from the bolt reflects back up into the cloud & can be seen from the ISS as an oval brightness. At 7 seconds (according to the web-page it is at 06 secs but, as can be seen above, it showed on my monitor as 07) there is a very special event, which you can just see if you know what to look at:- a “Red Sprite”. Here is a close-up:-
So, what is a Red Sprite, and what does it have to do with noctilucent clouds? Well, to answer the second bit first, they both occur at the same height, which is to say right at the top of the Mesosphere. Answering the first bit is going to blow your mind again:
http://en.wikipedia.org/wiki/Sprite_(lightning)
Optical imaging using a 10,000 frame-per-second high speed camera shows that sprites are actually clusters of small, decameter-sized (10–100 m, 30–300 ft) balls of ionization that are launched at an altitude of about 80 km (50 mi) and then move downward at speeds of up to ten percent the speed of light, followed a few milliseconds later by a separate set of upward moving balls of ionization.[8] Sprites may be horizontally displaced by up to 50 km (31 mi) from the location of the underlying lightning strike, with a time delay following the lightning that is typically a few milliseconds, but on rare occasions may be up to 100 milliseconds.
(hmm)
There have been lots of folks across the ages that have left comments on having seen such stuff, but the scientists just did not believe them. Then, on July 6, 1989, some scientists using a low-light camera captured a picture of a sprite (they were actually trying to photograph something else). They could not deny it after that.
The sprites are named after ‘Puck’, the spirit of the air from Shakespeare’s A Midsummer Night’s Dream.
--------- Alex Kemp