Space and Physics
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An enormous red circle briefly appeared in the Italian sky last week. This fleeting event, lasting a fraction of a second, looks like the dusting of a crimson doughnut but in reality, is a rare atmospheric event known as an ELVE. ELVES are an Emission of Light and Very Low-Frequency perturbations due to Electromagnetic Pulse Sources, one of those backronyms that makes you roll your eyes so hard you fear they might get stuck.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.ELVES are an excitation of nitrogen in the atmosphere caused by electrical discharges, taking the color red like in the lower edges of northern lights. They are flat and they can extend for hundreds of kilometers in the ionosphere. These peculiar events were only discovered in 1990 by the crew of Space Shuttle Discovery on the mission that sent the Ulysses probe to study the Sun. But unlike northern lights, they are not related to solar activity.
These ELVES are a product of thunderstorms and in fact, they are seen high above them. The electrons that interact with the nitrogen might have been energized by what goes on below it.
The author of the image is Valter Binotto, an Italian photographer who has previously won the Wildlife Photographer of the Year Award. He was following a thunderstorm about 300 kilometers (186 miles) from his location when he snapped this photo of the event.
ELVES are not the only whimsical phenomenon related to thunderstorms. There are blue jets, red sprites, TROLLs, Pixies, GHOSTs, and Gnomes. There are a lot of transient luminous events happening in the upper atmosphere which are not well defined: as they often form above thunderclouds, it is difficult to study them from the ground.
But sometimes, there are good alignments between distant storms and a camera in the right place at the right time, like this painting-like image of red sprites in Chile. Maybe it was a good choice to name them after mythological beings since it is so difficult to see them.
[H/T: spaceweather.com]
