Wednesday, August 05, 2009

Was it a TROLL crawling up above the Czech Republic? (UPDATED)

On the night of 2. August, big storm sweeped over the Czech Republic.



From Sopron, Hungary, several amazing sprites have been captured and something else, too... See the movie.

video

I guess it was a TROLL (Transient Red Optical Luminous Lineament). It is visible only on 2 video frames (1 frame covers 20 ms time interval). Here's a still image.



Feel free to leave a comment!

Cheers, Jozsef

UPDATE

There are differences between this event and those which have been observed in the US (Lyons et al, 2000), which suggest that what we have seen here is something other than a classic troll. (Please see the comments as well.) The most important difference is in the speed: US trolls crawl slowly upward, they are visible for 100 ms or a bit even more. Their head is less compact. On the other hand our event lasted for 40 ms maximum and its head was like an arrow head. Othervise the behaviour of the two TLEs seems to be rather similar. So I think I keep the name but I am going to call this guy a "quickie troll" to distinguish him from his relatives in the US.

3 Comments:

Blogger פרופ' יואב יאיר said...

Jo'zsef, how does this differ from a column sprite> I see some overlap of streamers but not sure it is something other than a sprite.
Yoav

August 07, 2009 6:28 pm  
Anonymous Jozsef said...

Dear Yoav, thanks for the comment! All I know about TROLLs is from a paper on SPRITES '99 campaign by (Lyons et al, 2000). This observation is more or less in accordance with the description on TROLLs given in that paper. There are, however, differences, too. This is why I have posed this record with a question in the title. This event is similar to the US TROLL in that it seems to start low at tendril heights. It is hard to tell the exact height on the other hand without knowing the location more precisely. It seems to move upwards just like the TROLL in the description and the shape of the two events are rather similar, too (e.g. both have a 'head'). It lasts, however, only for two frames - the US TROLL had longer lifetime. Another difference is that this event was not attached to an especially big sprite (although there occurred a big one near it just before). Despite these differences and taking into account the great diversity of upper atmospheric TLEs I tend to claim that the event we observed was closer to the TROLL which have been caught in the US than to a sprite. Unfortunately I don't have information on how many TROLLs have been captured ever and how many cases the description in the paper was based on...

August 10, 2009 12:10 pm  
Blogger Oscar van der Velde said...

It could be some form of secondary TLE. What was originally meant by "troll" seems to be a small thing sliding up a previous tendril. There is also the "palm tree" described in the thesis of Matt Heavner, these are also studied in Marshall et al.'s 2007 secondary TLE article. But those have a more visible stem at low altitudes and upward branches. Perhaps there are intermediate forms.

September 25, 2009 6:42 pm  

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