Sprites are rare and fleeting events, lasting between just 10 and 100 milliseconds (Image: Steven A Cummer, Duke University)

Mysterious flashes of light called “sprites”, that occur above thunderclouds during powerful storms, have been captured on film in unprecedented detail by researchers using an ultra-high-speed camera.

The best images yet of the flashes – which resemble a giant undulating jellyfish with its tentacles falling from a halo of light – have allowed the team to pick apart their structure and mechanics.

Sprites are fleeting events, which normally last between 10 and 100 milliseconds. The researchers hope their results will help inform models of the chemical and physical nature of the flashes.


In summer 2005, researchers from Duke University, US, and collaborators from FMA Research in Fort Collins, Colorado, US, kept a watchful eye on the skies above the Great Plains from the Yucca Ridge Field Station in Fort Collins, hoping to capture sprites in action using their 7000-frames-per-second camera. And capture it they did. Previously, the best published sprite images were recorded at 1000 frames per second.

Lightning streamers

“The whole structure develops a lot in one millisecond. So by going with the faster video we really see all the pieces and how they develop in time,” says Steven Cummer, assistant professor of electrical and computer engineering at Duke’s Pratt School of Engineering.

And with so much energy being pumped into a small region, Cummer says sprites may drive atmospheric chemistry that does not normally occur. “The significance at this point lies in what chemical effects these [sprites] may have on the upper atmosphere,” Cummer told New Scientist.

The researchers say sprites typically begin at an altitude of about 50 miles (80 kilometres) in the sky in single spots where the electric field creates a spark. Those produce falling “streamers” that branch out as they fall. Much brighter, thicker channels follow, expanding upward from the original spots.

Natural beauty

Based on the new images, the team says “isolated dots” that glow intensely and often outlast the rest of the sprite are the result of a collision of streamers. Cummer says such collisions may account for as many as half of the observed dots.

In July and August 2005, the group imaged 66 sprite events above Kansas and Nebraska. They captured their clearest images on 13 August, their final day of observations. Their findings from that event are to be posted in the online version of Geophysical Research Letters on 22 February.

“When a sprite is captured on film, it’s extremely exciting,” says Nicolas Jaugey, a member of Cummer’s team. “You just see a flash on the TV screen, but when you retrieve the recording from the high-speed camera and see its development, it’s very beautiful.”