If you see a thunderstorm in the distance late at night, look at the sky above the clouds and watch closely. You might just glimpse a sprite.
Sprites are a type of transient luminous event, like lightning, but fainter, faster and significantly larger, Jessica Leigh Hester explains for Atlas Obscura. Stephen Hummel, a dark sky specialist at the University of Texas at Austin, photographed a red jellyfish sprite on July 2 from the McDonald Observatory in Texas. The bright red formation appears to float between 28 and 55 miles high in the atmosphere, with a dispersed red cap and a flurry of tentacles underneath, Hummel tells Smithsonian magazine via email.
"Sprites usually appear to the eye as very brief, dim, grey structures. You need to be looking for them to spot them, and oftentimes I am not certain I actually saw one until I check the camera footage to confirm," Hummel tells Business Insider’s Aylin Woodward.
"While this is ordinarily true, this was no ordinary sprite," he writes Smithsonian magazine in an email. "I could clearly and unambiguously see it with the naked eye, although it was extremely brief. I immediately knew I had something spectacular. The coloration was very subtle to the eye because the human eye is not adept at seeing color in low light conditions, especially red, but the structure was all apparent."
To capture a sprite on camera, he usually needs to collect several hours of footage. This year, he's collected 70 hours' worth of footage amounting to about 70 sprites, half of those appearing in one storm, he tells Business Insider. He recorded four and a half hours of footage in order to photograph one sprite.
To see a jellyfish sprite, you need to be far away from the thunderstorm and watching it late at night in a place without much light pollution. Hummel spotted his sprite from about 100 miles away at 1:30 AM, he tells Atlas Obscura. The storm also needs to be making a lot of lightning. The Great Plains during the spring provides great opportunities to catch sprites, Matthew Cappucci wrote for the Washington Post in 2019.
Thunderstorms’ electrical activity goes beyond their classic lightning bolts.
“Regular lightning is really, really hot and energizes everything so much that almost all wavelengths of light are generated, making it white,” says Duke University electrical and computer engineering expert Steven Cummer to Atlas Obscura.
“Sprites are much lower energy, and thus only energize a few different molecules in air. The red color comes from energized nitrogen gas in the atmosphere.” Sprites can also look purple in low altitudes, Atlas Obscura reports.
Usually this weaker electrical discharge follows a positive lightning stroke, which happens when a cloud builds up positive charge.
“Negative strokes, from a buildup of negative charge, are about 10 times more common, so sprites aren’t strongly associated with the most common kind of lightning, but it’s not really that uncommon either,” physicist Jason Ahrns told Megan Gambino at Smithsonian in 2013. “More than just a positive stroke, the more charge that was moved during the stroke, the better the chances for a sprite.”
Sprite-chasers can target storms with a lot of positive lightning strokes to maximize their chances of catching sprites on camera, Ahrns says.
This summer, Hummel spotted a jellyfish sprite, characterized by its wide red top and tendrils of red lightning reaching out underneath. Well-formed jellyfish sprites are rare. Sprites commonly come in other shapes, like columns and carrots, too. And while lightning bolts are just an inch thick and miles long, jellyfish sprites can reach 30 miles across, per the Washington Post.
The existence of sprites was only confirmed in 1989, but since then, they’ve been photographed on every continent but Antarctica. Astronauts have even spotted sprites from space.
Editors' Note, August 31, 2020: This article has been edited to clarify some specifics about the phenomenon and the circumstances of Hummel's July 2 photograph.