Monday, October 29, 2007

Sprites 25-26 October and 28-29 October

It should now be clear what the real sprite season is! Not the summer, but the fall season with numerous thunderstorms over the Mediterranean Sea.

During the night of 25-26 October the Pic du Midi camera was operated after 23 UTC and caught 4 sprites south of the Mediterranean coast of France (west of Corsica).

During the night of 28-29 October the Pic du Midi camera only ran reliably after about 2300 or 0000 UT and caught 10 sprites, again near the southeast coast of Spain. This time it was clear also in Lannemezan, operated by Serge Soula, who obtained 22 sprites. Again, Pic du Midi did not trigger on the weaker events, so it needs to be tuned better for next year.
In both nights the moonlight on the clouds and mountains added a nice atmosphere to the images :)

Pic du Midi:

Lannemezan (fireball! -peakhold image):

This is the same sprite as shown above for Pic du Midi. This is a peakhold image, so stars show up better and is less noisy. The Watec 902H2 Supreme does not feature manual gain control, and the lowest gain setting is actually too high for the brightest sprites, losing detail. On the other hand, the camera at Pic du Midi, a 2/3rd inch JAI, is not as sensitive but captures brighter parts with fine nuances (even better in the raw image than in the picture shown) and higher resolution .

41 sprites 16-17 October

The night of 16-17 October it was a big Mediterranean sprite fest once again!
Cameras from Lannemezan and Pic du Midi were operated, La Molina probably too. 1 caught from Toulouse, unfortunately there is a flat blocking my view for anything more northeast than the line Toulouse-Ibiza and besides that, the permanent light on that flat attracts bugs and thus numerous bats which trigger the camera continuously :-S
Pic du Midi lost internet connection around midnight, apparently it was shut down somehow. The count from Lannemezan is 41.

The nights of 15-16 and 17-18 October were good for 2 and 4 sprites, respectively.
Some images follow later.

Many sprites: October 11-12 and 12-13!

A small active low pressure area generated many thunderstorms over the southwestern Mediterranean Sea these days.

Many sprites were captured with the camera from Pic du Midi, some from Toulouse (very low near the horizon), and some from La Molina. The latter locations could have detected more if technical problems would not have occurred. My laptop hard disk crashed and most of the sprite footage of this night was lost. I then continued operating Pic from my office after a 7 km bike trip.
The UFOCapture software combined with a Watec camera actually detected also a number of smaller sprites not detected by Pic du Midi, so the number of sprites detected by the latter is only a subset of those that truly occurred.
Several sprites can be triangulated to find their exact locations, which is very important for detailed studies.
The count for 11-12 October is about 65 events: sprites, an elve and one or two sprite haloes. The first good color images have been obtained from Pic du Midi.
Here are the most interesting images:

color image of the above sprite:

sprite with halo:
Classic carrot sprite with halo:
a closer classic column sprite:

The following sprite clearly follows the electric field lines to a confined region of charge:

The below sprite event is the most impressive. It consists of two parts. A huge area of columniform sprites...

...quickly followed by a very tall sprite cluster:
This one looks like it may include a troll (upward secondary event), though not in apparent connection to the cloud:
Some sprites are difficult to classify at all...

The count for 12-13 October is 16 sprites and a very nice elve. They could be recorded even from 700 km distance, with the storms near the Algerian coast!
Some images:

The elve: