One unusual feature of sprites is that they are relatively cold - they operate more like long fluorescent light tubes than hot compact light bulbs.
Sprite Lightning in HD | NASA Astronomy Picture of the Day
This phenomenon occurs in the sky over our heads, not the sea. It is a type of lightning known as red sprite, and rarely has it ever been photographed in this detail. Even though sprites have been recorded for over 30 years, their root cause remains unknown. Some thunderstorms have them, but most don't. These mysterious bursts of light in the upper atmosphere momentarily resemble gigantic jellyfish. A few years ago high speed videos were taken detailing how red sprites actually develop. The featured image was captured last month in high definition from Italy. In general, red sprites take only a fraction of a second to occur and are best seen when powerful thunderstorms are visible from the side.
Sprite Lightning in HD | NASA APOD
Cold, heat is a definition. What and where exactly are you measuring? What are your baselines?
Do Double Layers plasmas and other electromagnetic plasmoid features mask energetic processes happening inside the filaments?
Dusty plasmas in space, astrophysical jets (relativistic jets, relativistic plasma is collimated into jets) are often said to be measured as millions of degrees hot yet could just be energetic, excited, ionised, and not quite as hot.
Were upper atmosphere lightning sprites observed and recorded by older civilsations and inspired their mythology, religions and gods?
Red sprites, upwards lightning, are one component in Earth's Global Electric Circuit. Which links to the solar system electromagnetic circuitry, systems and feedbacks.
If these sprites are relatively cold then is it due to their filamentation being in a less energetic plasma glow mode? How their possible Townsend type electron avalanche discharge occurs?
Plasma discharge structures can imply Plasma and Electric Universe cosmology.