🟥 🌩 This image beautifully captures a red sprite, a rare and transient upper-atmospheric phenomenon, photographed from the International Space Station (ISS).
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#RedSprite #UpperAtmosphericLightning
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@NASA
▶️ Red sprites are large-scale electrical discharges that occur high above thunderstorm clouds, typically at altitudes of 50–90 km (mesosphere and lower ionosphere).
They appear as reddish-orange jellyfish-like structures with dangling tendrils below and diffuse glowing regions above.
In this photo, you can clearly see:
▪️ The bright central column with a vivid red-to-purple hue
▪️ Faint downward-streaming tendrils (the “jellyfish tentacles”)
▪️ A bluish-white carrot-shaped core at the top
▪️ The curved limb of Earth with a thin green airglow layer and the blackness of space beyond
Part of an astronaut’s arm in the foreground, giving scale and context.
▶️ Sprites are triggered by powerful positive cloud-to-ground lightning strokes ( CG) in the underlying thunderstorm.
Here’s the simplified process:
↘️ A strong CG lightning bolt removes a large amount of positive charge from the thundercloud top to the ground.
This suddenly leaves the cloud top with a huge excess of negative charge.
↘️ The intense electric field above the storm breaks down the air at mesospheric altitudes (where air pressure is extremely low).
↘️ Electrons avalanche upward and downward, exciting nitrogen molecules, which emit the characteristic red light (primarily the 1st positive band of N₂ at ~650–750 nm).
The blue/violet tones come from ionized nitrogen (N₂⁺).
Because they occur so high and last only milliseconds, sprites are usually only visible from space or from very distant, dark locations on the ground with an unobstructed view above active thunderstorms.