Indeed. Two decades ago an astonishing phenomenon was discovered: intense flashes in the mesosphere , a region of the atmosphere located thirty miles above the ground and believed to be devoid of activity. These flashes, related to thunderbolts but located tens of kilometers above the clouds, were dubbed sprites .
Sprites are light events that last hundredths of a second and show a fuzzy upper part and a lower region populated with “tentacles”. They can extend from 40 to almost 100 kilometers above the ground and are produced simultaneously with the lightning that triggers them or with a certain delay.
A sprite occurs when a thundercloud has a negative electrical charge at the bottom and a positive charge at the top . Generally, the rays emerge from the lower region and show negative polarity, but sometimes rays with positive polarity emerge, much more powerful and dangerous. The latter produce an electric field that rises towards the upper atmospheric layers and that triggers the sprite . Several chemical reactions that generate free electrons are required for them to occur. Scientists from the Andalusian Institute of Astrophysics (IAA-CSIC) have now discovered that there are not two reactions, as previously thought, but three (the third called “associative detachment”) that put electrons into circulation. Their results have been published in the journal Nature Geoscience .
Sprites constitute a type within a wide family of electrical phenomena that take place in the mesosphere, which are known as Transient Light Events (TLEs) and among which are also elves , halos, blue jets and gigantic blue jets .
