As Hurricane Matthew intensified into a Category 5 storm in the Caribbean this weekend, the tempest also produced vibrant colours in the sky. The rare atmospheric phenomena, known as lighting sprites, were photographed by an observer about 400 miles southwest of Puerto Rico.
The lightning sprites were seen as fleeting flashes of brilliant red light above the clouds.
Sometimes called "upward lightning" and "cloud-to-stratospheric lightning," sprites are momentary bursts of electricity that can literally reach the edge of space, about 50 miles above the ground. They're rarely documented because they are so short lived (typically about 10 milliseconds) and are often obscured by clouds. In fact, evidence of sprites is so rare, the phenomenon was thought to be a myth until it was photographed by a pilot in 1989.
Closely related to more typical lightning, sprites are thought to be produced when discharged electricity shoots out from the top of a cloud, instead of heading to the ground. Sprites are typically formed above powerful thunderstorms or hurricanes, where lots of electrical energy is churning.
See another view of the sprites over Matthew.
Still, the precise details of how sprites form is unknown. Scientists also don’t know if they play some important role in weather or if they're merely curiosities.
Here are a few tips on observing sprites from Andrew Fazekas, National Geographic’s Night Sky Guy: “To see them with the naked eye during a storm, find a sheltered location far away from the blinding lights of the city. Haze and air pollution can also block sprites from view.
“Gaze well above the top of a thundercloud while blocking out all the lightning action below with a piece of cardboard. Expect them to occur every 10 minutes or so on average at the height of the storm.”