Graduate student Christopher Sterpka remembers the first time he saw ball lightning, as a 9- or 10-year-old staying at his grandparents’ house in West Hartford, Conn. He was home alone and watching a thunderstorm from a window one summer night.
“I remember this blue, kind of fuzzy ball just sort of descended diagonally out of the clouds,” said Sterpka, who conducts research in lightning physics at the University of New Hampshire’s Space Science Center. He watched the ball of light float down to the ground in the distance and disappear out of sight in a matter of 5–10 seconds. “I was terrified.”
Sterpka told his grandfather, a science teacher, when he returned home. His grandfather had no idea what it was but asked around. That’s when they heard what the strange sighting may have been: ball lightning. “It’s actually one of the incidents that probably got me interested in lightning in the first place.” Sterpka saw ball lightning again in his twenties while driving near a thunderstorm in Massachusetts.
Ball lightning has been reported for centuries but hasn’t been reliably observed by scientific instruments. A new website hosted by New Mexico Tech physicist Richard Sonnenfeld and Texas State University engineer Karl Stephan is collecting eyewitness accounts to improve the basic understanding of the phenomenon. They’ll compare the accounts with weather radar systems to characterize the factors that could lead to ball lightning.
“This is one thing that hasn’t been done,” said Martin Uman, a lightning scientist at the University of Florida who is not involved in the research. When it comes to ball lightning, there are lots of observations, but “nobody has correlated any of the observations with any other measurements.”
If ball lightning turns out to be explainable by science, the findings could revolutionize our understanding of physics. As it stands, nothing can explain a glowing ball with no fuel source that can last up to a minute, said Sonnenfeld. “That’s fascinating physics,” he said. “Revolutionary physics even, if you can believe it.”
A Scientific Riddle
Eyewitness accounts describe hovering balls of light typically about 20 centimeters in diameter, roughly the size of a bowling ball. The balls appear white, yellow, orange, blue, or (rarely) green and can last from mere seconds to up to a minute before fading, flashing, or exploding into nothing.
People have seen ball lightning outside their windows from a distance, mere meters away in their kitchen, roving down the aisles of airplanes, and coming down their chimneys. Other reports are widely different, like a luminous ring the size of a truck that lasted 10 minutes, as described by an Austrian woman. The balls of light typically happen during thunderstorms and may have led, in very rare cases, to burn injuries or deaths.
“In my opinion, there are probably multiple causes for what’s described as ball lightning,” Uman said.
Despite hundreds of eyewitness accounts from across the world and going back centuries, scientists can’t explain ball lightning or re-create it in the lab. Theories abound: Ball lightning is the result of a failed lightning bolt, of hot ionized silica, or of chains of charged particles. One paper even proposed that ball lightning came from magnetic stimulation in the brain. “I think that a lot of the theories have a piece of the truth,” Stephan said, “but none of them have the whole truth.”
“There are literally dozens of ball lightning theories because it’s an unconstrained situation,” Stephan said. “Since there [are] virtually no data, anybody can come up with a theory, and you can’t prove them wrong.”
A self-described “wet blanket” in the niche world of ball lightning scholarship, Stephan wants to “clear the underbrush” of scientific theories and see what’s left.
The public reporting website launched last year might help with that. Eyewitnesses fill out a Google form with the location, date, time, and description of the ball lightning sighting and send photos or videos to an email address.
Stephan and Sonnenfeld have received written reports of sightings from decades ago, like Sterpka’s account. Those are helpful, Sonnenfeld said, but he hopes for more recent sightings with more exact information.
Thunderstorms are tracked across the globe using national and global lightning networks that record every flash (with some error). With precise location and time information of a ball lightning sighting, the team could check how close a thunderstorm was to the event. The team could also investigate the charge of the nearby cloud-to-ground lightning (positive or negative) and the current of the lightning to learn more about the conditions. This kind of technology was not around 20 years ago, said Sonnenfeld.
It turns out there is a precedent for eyewitness accounts of strange lightning occurrences that turn out to be real.
For decades, pilots spoke of strange pink flashes of light above thunderclouds, but scientists had no explanation for the phenomenon. It wasn’t until a physicist accidentally captured a similar event on a low-light television camera while testing equipment for a rocket launch that the phenomenon came to light, wrote Matthew Cappucci for the Washington Post. This special type of lightning is called a sprite, and it occurs 50–90 kilometers above the ground, in the mesosphere. (For comparison, airplanes fly about 9–11 kilometers up.) Sprites flash reddish light over massive patches of sky for less than a tenth of a second. They’re said to happen after a positive bolt of lightning hits the ground from a thunderstorm below.
The perfect sighting of ball lightning would include multiple witnesses with accounts that agree, videos from more than one angle, the object casting a shadow, and enough detail to compare with radar. “No ball lightning sighting has had all that good stuff happen yet,” Stephan said. “But maybe it will someday.”
—Jenessa Duncombe (@jrdscience), Staff Writer