Friday, September 25, 2009

Very large sprites September 1-2

East of Perpignan a very active circular storm complex produced some very large sprites in the early morning of last September 2nd, caught by a camera at Pic du Midi. Several events consisted of a long lasting sequence of groups of sprites. The tendrils reached very low altitudes measured to be 30-35 km and, with secondary TLE (troll?) extending below it and lasting for 40 ms. The lower visible part of the troll above an interfering cloud bank is at an altitude of around 27 km, so it is quite high above the cloud tops, still.

Here are some frames of an earlier one, starting with the 3rd frame of the sprite (initial two frames show column sprites, extending downward with a dark band in between (a strange behaviour I've noticed also in earlier secondary TLE events), followed by a very low carrot sprite, the massive group, disappearing with no traces left in the next frame, and like in the other case, remaining activity at low altitudes.

Note also the remarkable geometry of the bunch of tendrils. This could be a very interesting case for more in-depth study in combination with ELF data.