Picture an eerie red glow, high in the night sky, flickering ominously above a violent thunderstorm. Though such an apparition sounds like otherworldly magic, it is actually a very real atmospheric phenomenon referred to as sprites.
The first known written record of a sprite sighting was in 1730, but it took until 1989 to successfully photograph these mysterious lights. Like those in the photograph (taken in the Czech Republic), sprites generally appear red to orange in color and vertically elongate in shape. Sometimes a similarly-colored “halo” also appears above sets of sprites while they flash and flicker.
During the many years I spent as a Weather Observer, I have never witnessed sprites. Sprites are similar in some ways to lightning, but wildly different in others. Both are atmospheric phenomena made of plasma that occur due to electrical activity during storms. Unlike lightning, which reaches temperatures hotter than the surface of the sun, sprites are made of cool nonthermal plasma, similar to mercury vapor fluorescent light bulbs. Lightning and sprites also take place at vastly different elevations; lightning generally occurs in the troposphere (less than 10 km above the earth’s surface), while sprites occur in the mesosphere (50-100 km above the earth’s surface).
Sprites are an astounding sight, but very particular circumstances are required to see them. Because sprites occur above powerful thunderstorms, they are often obscured from view by the storm’s clouds. Sprites can be seen from the ground only on the rare occasion that a strong enough storm has a cloud-free area nearby. These apparitions can be observed more reliably from space; astronauts aboard the International Space Station can see sprites far more often than the average person.