National Geographic Your Shot submitter Peter Vancoillie took the photograph from about 18 miles (30 kilometers) away from the volcanic lightning storm, which not "unlike a regular old thunderstorm," said Martin Uman, a lightning expert at the University of Florida in Gainesville.
The same ingredients are present: water droplets, ice, and possibly hail—all interacting with each other and with particles, in this case ash from the eruptions, to cause electrical charging, Uman said. (See pictures of the Iceland volcano's ash plume.)
The volcanic-lightning pictures are "really very sensational," Uman said. "Somebody ought to be up there with an HD movie camera—it's ready for the IMAX theater."
Photograph by Peter Vancoillie, Your Shot
Purple Bolts at Iceland Volcano
Italian photographer and scientist Marco Fulle flew at sunset on Sunday over Iceland's erupting Eyjafjallajökull volcano to capture this picture of purple lightning bolts streaking through the sky.
It's unknown how such sparks form, though one possibility is that electrically charged silica—an ingredient of magma—interacts with the atmosphere when it bursts out of Earth's crust, Steve McNutt of the Alaska Volcano Observatory said in February.
Fiery lava mixes with blue ash and golden lightning over the erupting Eyjafjallajökull volcano in an April 18, 2010, picture.
The Iceland volcano's lightning is probably creating distinct symphony of sounds, said the University of Florida's Uman. For instance, small sparks of about 30 feet (9 meters) to about 300 yards (91 meters) make sounds like rifle shots, while the miles-long bolts produce the deep, familiar rumbling we associate with thunderstorms, he explained.
All types of lightning, particularly volcanic lightning, are still largely mysteries to scientists, University of Florida's Uman said.
Since people can't easily get inside thunder and lightning storms, no one knows exactly how they form, he said. However, scientists can install instruments near volcanoes' vents to measure certain data, such as the lightning-detection devices that scientists are installing right now in Iceland, he said.
Inhaling the tiny pieces of glassy sand and dust in the cloud can cause irritation of the eyes, nose, and throat, say experts who advise Europeans to stay indoors when the ash begins to fall. Finer particles can also penetrate deep into the lungs and cause breathing problems, particularly among those with respiratory issues like asthma or emphysema. (See "Iceland Volcano Ash Plume Prompts Health Worries.")
But if people could witness the volcanic lightning safely, it would be an incredible experience, Uman said.
"Everyone would want to see that," Uman said. "It's like going to see aurora borealis near the North Pole—it's a once-in-a-lifetime experience."