Red sprites seen over central Kansas on April 21, 2019
© Paul Smith
Red sprites seen over central Kansas on April 21, 2019.
A rare and elusive weather phenomenon was photographed last weekend in the central United States as severe thunderstorms swept across the region.

When lightning occurs, it usually either dances through the clouds of a thunderstorm or strikes the ground, but when conditions are right, a certain type of lightning bolt can extend well above the thunderstorm itself. This type of lightning is known as a "sprite."

The red color of the sprites is believed to be caused by the interaction between the sprites and nitrogen in the atmosphere, according to the University of Washington. This is why they are also known as "red sprites."

"Red sprites are short-lived, red flashes that occur about 80 kilometers (50 miles) up in the atmosphere. With long, vertical tendrils like a jellyfish, these electrical discharges can extend 20 to 30 kilometers up into the atmosphere and are connected to thunderstorms and lightning," NASA reported.

To put their size into perspective, most commercial jets fly at a cruising altitude of around 7 or 8 miles, just a fraction of the altitude of where sprites occur in the atmosphere.

This rare phenomenon was captured by nature photographer Paul Smith on two occasions over the past week when severe thunderstorms rumbled over the central U.S. Smith has been specializing in night photography since 2015, capturing mesmerizing images of the aurora, thunderstorms at night and red sprites.

Although sprites are bright and significantly larger than typical lightning bolts, they are seldom seen.

"Red sprites are difficult to observe because they last for just a few milliseconds and occur above thunderstorms -- meaning they are usually blocked from view on the ground by the very clouds that produce them," NASA said on its website.

"They are rarely seen with the human eye, so they are most often imaged with highly sensitive cameras," the National Oceanic and Atmospheric Administration explains in an article exploring various types of lightning.

Sprites are so large and emit so much energy that cameras and instruments on the International Space Station (ISS), which orbits about 250 miles above the Earth's surface, are able to detect them. Lightning research conducted in space originally helped scientists verify the existence of sprites 30 years ago.

For decades, pilots had reported large flashes of light extending high above thunderstorms, but their reports were largely discounted by the scientific community until the late 1980s.

In 1989, researchers at the University of Minnesota accidentally photographed sprites above a distant thunderstorm while using low-light cameras. Later that year, the existence of sprites was confirmed by instruments flying aboard Space Shuttle Discovery.

According to NASA, "in October 1989, Otha 'Skeet' Vaughan of NASA's Marshall Space Flight Center and scientists working on the Mesoscale Lightning Observation Experiment were able to verify the existence of these electrical discharges with their instrument on space shuttle flight STS-34."

Further research was conducted on additional space shuttle missions and from the ISS, which included the use of low-light cameras to photograph the phenomenon above thunderstorms around the globe.

A red sprite captured over Malaysia on April 30, 2012, by astronauts on the International Space Station
© Images/NASA/JSC
A red sprite captured over Malaysia on April 30, 2012, by astronauts on the International Space Station.
People hoping to capture an image of sprites for themselves need the proper equipment and a bit of luck. A low-light camera, such as a DSLR, a tripod, and the right perspective of a thunderstorm are needed to photograph a sprite.

"Viewers on the ground can photograph sprites by looking out on a thunderstorm in the distance, often looking out from high mountainsides over storms in lower plains," NASA explained.

However, sprites do not occur during every thunderstorm, so it may take several attempts to capture the elusive phenomonen in a photograph.

Anyone attempting to photograph lightning should do so with caution and from a safe distance as to not be in danger of being struck by lighting. Most lightning strikes close to a thunderstorm, but some bolts can strike over 10 miles away without warning.