Red sprites over a distant lightning system. Filmed in the Irbitsky district of the Sverdlovsk region on the night of August 3-4, 2017.
Sprites are poorly understood electrical discharges that hit the stratosphere, mesosphere and thermosphere. At the moment, it has been established that they occur over strong thunderstorms with an abundance of positive lightning between the cloud and the ground.
A little over a year ago, on August 2, albeit in low resolution, I still managed to capture the red sprites using an analog surveillance camera. Now, with a little experience and new equipment, I started observing again
On the evening of August 3, a powerful thunderstorm system began to form rapidly in the Tyumen region between Ishim, Tobolsk and Tyumen, possibly including one or more supercells. Just at that time, the sky over the east of the Sverdlovsk region cleared of clouds, which promised a clear night. The current situation provided an excellent chance to try out the new ultra-sensitive camera in action and try to capture sprites and other related phenomena in the upper atmosphere.
Using maps, satellite images, and lightning detector data, I determined the direction to the center of the thunderstorm system and established local landmarks, which I used to direct the new camera to the area where sprites are most likely to appear. It should be borne in mind that the thunderstorm is at a distance of almost 500 km and the sprites should be looked for not high above the horizon.
The result was not long in coming, already at the moment of fine-tuning the tripod I noticed the much-desired jellyfish-like discharges on the tablet screen. Since this was almost my first acquaintance with the capabilities of the camera, I had to deal with the sensitivity settings and other parameters directly at the moment of observation, which is why the picture quality on recording differs at different time intervals.
In total, with the help of the new camera, it was possible to record about 15 discharges at an altitude of about 10 ° above the horizon, most of which were identified as sprites. There were both huge and bright specimens, and hardly distinguishable ones. Often meteors flew into the frame.
Shooting parameters:
Promotional video:
Resolution - 1920x1080
Bitrate - 10 Mbps
Recording speed - 25 fps
Exposure per frame - 1/30
Focal length - 25 mm (ef 125 mm)
Aperture - f / 1.2
As it turned out a little later, the first to capture the sprites was the 2002 KPC-S190S camera, which continuously monitors the eastern horizon. In the dark, except for street lights, meteors and stars brighter than magnitude 0, she sees nothing at all. It would seem that this suggests that the sprites are bright enough for observation with the naked eye, but over the entire night I did not see anything like that. In this case, one should not exclude the fact that the CCD matrix of the old camera, although it does not have high sensitivity, is still susceptible to IR radiation, and a significant part of the sprite's brightness can be concentrated precisely in the part of the spectrum invisible to the eye.
An attempt was also made to shoot sprites on a DSLR. The attempt was generally successful, but the result turned out to be much more modest - with ISO2000 settings, shutter speed of 10 seconds and aperture of f / 4, only the brightest part of them is visible, and then after processing and stretching the red channel.
Quick reference:
Sprites are poorly understood electrical discharges in the stratosphere, mesosphere and thermosphere. At the moment, it has been established that sprites appear over strong thunderstorms with an abundance of positive lightning between the cloud and the ground.
Ilya Yankovsky