Monday, March 31, 2008
Courtesy Harald Edens
A thin bolt of lightning called a "blue jet" shoots out the top of this New Mexico thunderstorm in a rare image captured last summer by New Mexico Institute of Mining and Technology researcher Harald Edens.
Researcher Snaps a Rare Photo of 'Blue Jet' Lightning, a Bolt Striking Upward
By John Fleck
Journal Staff Writer
Lightning researcher Harald Edens at first did not realize what he had in his camera last July 19.
It was only later, as he was looking at his pictures, that he noticed the tiny flash coming off the top of a cloud a bolt of lightning going not down, but up.
"It was a pleasant surprise," said Edens, a graduate student at the New Mexico Institute of Mining and Technology's Langmuir Laboratory for Atmospheric Research.
This week, a group of researchers including Edens has gone a long way toward explaining how the rare and mysterious "blue jets" and their unusual lightning kin work.
The most common types of lightning bounce around inside a cloud, or come crashing down from a cloud to the ground beneath it. But, on rare occasions, lightning can take truly strange paths.
It can fly out the top of a cloud, as Edens' did. Sometimes, the upward flash can be gigantic.
And then there is the famous "bolt from the blue."
The storm cloud can be miles away, when suddenly a bolt of lightning darts from its side. It arches across the sky and touches down far from the rain and lightning, a bolt coming out of a clear blue sky.
In the scientific journal Nature Geoscience published March 23, a team led by Tech lightning researcher Paul Krehbiel goes a long way toward explaining what causes the different species in the strange menagerie of lightning.
Using data collected at Langmuir and elsewhere, combined with computer simulations done by team members at Penn State, the scientists show how such strange types of lightning compare with the ordinary cloud-to-ground bolts common to New Mexico thunderstorms.
In general, lighting happens when an imbalance builds up in a cloud's electrical charge much like the shock you get after shuffling your feet on carpet.
In ordinary cloud-to-ground lightning, a large negative electrical charge builds up in the center of a cloud. The lightning bolt begins at the bottom of this electrically charged region and comes crashing out of the bottom of the cloud.
The "blue jet" Edens photographed last summer happens when a massive positive charge builds up near the top of the cloud, sending a lightning bolt crashing upward.
Various combinations of positive and negative charges can send the bolts in a variety of directions, the scientists concluded.
For Edens, the summers are about more than just studying lightning. An experienced weather photographer, he thrives on thunderstorms.
"I'm nuts about photographing lightning," he said.