MSU researchers track ‘killer lightning’


Aug 30, 2007

Weather lab participates in federal Missile Defense pro

The violent thunderstorms that have rolled across Minnesota have been a treasure-trove of information for a group of researchers hunkered over computer monitors in a basement room at Minnesota State University.

Through a high-powered, light-sensitive camera mounted on the roof of Armstrong Hall, graduate student Josh Jans and others train the camera on the strongest storm fronts.

Their goal is to capture images — usually hundreds of miles away — of bright, powerful bursts of light above the clouds that last just a fraction of a second. They are one of six sites in the country working on the project for the U.S. Missile Defense Agency (the Star Wars program).

“With the storms this summer, we’ve captured more of them than anyone else,” said Jans, a grad student in MSU’s Weather Lab. His most recent capture was a dramatic bright flash above Brainerd during Monday night’s storms.

Cecil Keen, a professor of geography/atmospheric sciences at MSU, said there is interest in the powerful electrical flashes because they shoot upward where they can fry electrical components in everything from weather balloons, to satellites and high-flying jets.

The common cloud-to-ground lightning we see is negative lightning that starts near the bottom of clouds. But about 10 percent of lightning starts in upper clouds and is positive lightning — known as “killer lightning.”

Recently, researchers discovered some of those positive lightnings also shoot upward and a whole new family of lightning has come into being.

The upward flashes are referred to as mesospheric lightning. The mesosphere is the portion of atmosphere from about 20 to 50 miles above the earth’s surface.

References to mesospheric lightning go back to the 1800s with reports of quick, luminous flashes above the tops of cumulus thunderclouds. They are believed to account for some reports of UFOs.

The flashes are called sprites and can be white or colored. Sprites were only recently verified — just over a decade ago — by aircraft using high-speed video.

At MSU, Jans and others head to the basement weather lab when promising thunderstorms are predicted. For the system to work, the sky must be clear above Mankato. “We need to see atop the storm clouds, so cloud cover here dooms us,” Keen said.

The camera is extremely light sensitive and powerful. It has captured images across Minnesota and neighboring states, as far as Illinois.

The system uses a software, aptly called UFO. Jans directs the camera to the part of the sky he thinks will be most promising based on the live radar he monitors on another screen. Because of its high light sensitivity, he then uses the software to mask any lights from campus or the area that would trigger the camera.

The camera automatically saves any light images it captures. Then, after the storm, the hard work comes.

“The tedious part is going through each frame to see if it’s a sprite or just regular lightning or a light from an airplane,” Jans said.