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Ursa Astronomical Association

Upper-atmospheric lightning - 20.5.2014 at 02.05 Helsinki, Pukinmäki Observation number 25890

Visibility Unclassified

Esko Lyytinen, Ursa (Helsinki)

The image of the fireball camera shows a possible top flash, a sprite. The image is a 2-minute Peak-hold image that ended exactly at 06 minutes. It is exactly the same time image as Mikkeli's top flash image.

However, the destination is not the same. This would be north of here. It seems that in the picture from the southeast side, lightning (which caused Mikkeli's picture spriten?) Illuminates nearby trees. Apparently, however, from the north, lightning illuminates the edges of a couple of clouds (even from the sky, but difficult to distinguish from the twilight sky). And this sprite would be out of that flash. However, in a Peak-hold image, it must compete not only with an otherwise bright sky but also with the brightness level of another image raised by lightning (probably at a different time).

If the lower part were at 60 km, then it would be located at 25.13 E, 60.78 N. But if it is as high as the one determined in Mikkeli (80 km) then it would be 25.18 E. 60.96 N.

So I don’t consider this to be a sure top-flash observation, but it’s not a typical radiation trace, and hardly a reflection from the camera shield from the rear flash.

Most of the time (after the thunderstorms started), the clouds covered the sky area that could have been visible. There was an opening in that.

I added contrast to the image.

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Comments: 1 pcs
Panu Lahtinen - 20.5.2014 at 20.20 Report this

Kirjallisuudesta muistan myös havaintoja, joissa yläsalamat ovat muodostuneet satakin kilometria sivuun ne synnyttäneistä maasalamoista. Lisäksi on joitakin tapauksia, joissa myös pilvisalamat ovat saaneet aikaiseksi yläsalamoita. Ja koska Suomessa ei ole varsinaista pilvisalamapaikanninverkkoa, voi ne jäädä havaitsematta, vaikka kaikki maasalamat olisikin paikantuneet (100 % hyötysuhdetta ei toki ole niissäkään).

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