Saturday, November 18, 2006

The Revenge of the Sprites - 17 sprites on 17 November

November 17th. You thought it wouldn't happen anymore this year? Just two days after the dismantling of the camera at Pic du Midi, a thunderstorm system grew over the Mediterranean coast of France. Here in Toulouse we had perfectly clear conditions, so we've set up the camera system on the roof of our lab during dusk. Initially we pointed east and we got a distant thunderstorm flash in view, so it seemed good! Serge left to visit a theater show.

After a look at the radar I decided I had to point more towards the northeast, to the stratiform precipitation region. At 19:09 UTC the first sprite appeared in the left side of the image, so after this I pointed even more northeastward and after that ...a total of 17 beautiful sprites happened full in view! The last one occurred at 20:52 UTC, so on average there was a sprite every 6 minutes.
Meanwhile I swept the excessive dew from the equipment and tried to see sprites by myself, but I couldn't see any of them this time.

Enjoy these! They are raw event summary images from UFOCapture.














14: dedicated to my girlfriend Carmen, who sms'ed me back that she is my 14th sprite:




As you can see, most sprites were carrots! Several of them have relatively small bodies but tall branches. Big groups filled the whole field of view, I couldn't stop grinning! :-] The lightning flashes that preceded the sprites were also visible and all traveled from right to left.
Serge came back from the theater half an hour after the last sprite occurred. It appears we each had our own theater ;-)
After that it slowly became foggy, and the storm did not come back into a good shape.
A very good observations night, of which I consider the period 1912-2130 UTC fully documented, with our newly arrived GPS video time inserter up and running!

Thursday, November 16, 2006

Campaign finished! Latest images...

Olivier Chanrion has just announced that technicians have unmounted the camera at Pic du Midi for the winter season. The camera in Toulouse/Mont Aigoual can still be used if a rare good winter situation occurs. I will show you the last sprites that we have not reported yet that were observed on October 18/19th and 23/24th.

Let's start with the most beautiful sprites of the night of 17-18 August, mostly carrots, that never showed up here. Torsten Neubert, the coordinator of our project, caught 11 sprites with the camera on Pic du Midi. The moon and the distant city lights (Toulouse) give a picturesque impression. The images have been cropped. Cloudy skies were forecast for the sky over Mont Aigoual, so we did not operate from there.

In the late afternoon of 18 October storms began to develop over northeastern Spain. A very long-lived complex lasted till about 01 UTC and stayed in the same position all the time. Between 1927 and 1944 UTC, Pic du Midi was relatively clear and caught 4 sprites. After that, no sprites were observed anymore because the mountain was again swallowed by the cloud deck. From the almost continuous positive lightning strike patterns at the northern end of the convective line, my guess is that the storm produced more than 30 sprites during these hours. Very frustrating to have so many clouds every time...

The sprites appeared fairly dim:

(cropped from the original images)

A week later, Michal Ganot remotely operated the Pic camera from Tel Aviv. It was a situation with an active depression moving into northwestern France, with instability present near and behind the cold front that crossed France in just a few hours. 3 sprites were recorded from at least two different storms, one behind the cold front and one embedded in the cold front when it reached the Alps.

The very nice group of columniform sprites (cropped):

This last +CG strike had a huge peak current of 202 kA. The sprite is accompanied by a weak sprite halo:

It was interesting to see where such a powerful +CG struck. One can enter the coordinates in Google Earth and get the following scene (the CG may as well have struck the mountain top):