A Penn State graduate student, sitting in a field in central Pennsylvania, is capturing a record of sprites and elves that were seen over northern Texas. Not the mythical creatures from a storybook, but these sprites and elves are optical phenomena that occur during some thunderstorms. Sprites are red, vertically oriented flashes of light caused by ionized nitrogen that appear above thunderheads and can rise from 30 up to 50 miles above the ground. They are 1 to 60 miles in diameter.
Sprites last only a few tens of milliseconds.
Elves are diffuse glows of ionized gas molecules that occur just below the ionosphere about 56 mile above the ground. Shorter-lived than sprites, they last for only a few hundred of microseconds. Sprites and elves can occur individually or together. Sprites can barely be seen with the naked eye and are easily photographed with low-light cameras. However, elves are fainter, and we require light amplification equipment to see them.