“Upside down” lightning as powerful as strongest Earth-bound Bolts

August 24th, 2009 - 12:10 pm ICT by ANI  

National Geographic Washington, August 24 (ANI): In a new research, a team of scientists has determined that lightning that shoots upward from clouds can be as powerful as the strongest bolts that strike the ground.

According to a report in National Geographic News, these rarely seen, highly charged meteorological events are known as ‘gigantic jets’, and they flash up to the lower levels of space, or ionosphere.

While they don’t occur every time there is lightning, they are substantially larger than their downward striking cousins.

But researchers had witnessed gigantic jets just a handful of times, leaving much unknown about the strength and electrical activity of the unusual lightning strikes.

On July 21, 2008, a team led by Steven Cummer at Duke University in North Carolina had a stroke of luck.

The scientists had set up an automated video system equipped to study magnetic activity from thunderstorms moving through the area around the university.

“My research group had actually been interested in studying sprites, a different lightning phenomenon in the upper atmosphere,” Cummer said.

Six months into the project, tropical storm Cristobal moved over the region, and the video system captured a gigantic jet rising from the tempest.

“Essentially nothing was known about the electrical nature of gigantic jets, (so) we immediately started analyzing our data to understand what was going on,” Cummer said.

The researchers found that the upward lightning carried 144 Coulombs of electrical charge.

Whereas a conventional lightning bolt follows a six-inch channel and travels about 4.5 miles down to earth, the gigantic jet recorded by the scientists contained multiple channels and traveled about 40 miles upward.

“This gigantic jet carried as much charge to the upper atmosphere as the very biggest cloud-to-ground lightning strokes, about a hundred to a thousand times bigger than a typical lightning stroke,” Cummer said.

The finding totally shocked the research team, since it’s the first clear proof that an electric charge can move directly from the troposphere into the ionosphere, two layers of Earth’s atmosphere.

Until now, “we didn’t know whether gigantic jets actually made electrical contact with the upper atmosphere to discharge the thunderstorm,” Cummer said.

“That thunderstorms can be electrically connected to the upper atmosphere and push quite a bit of electric charge up there is a surprise,” he added.

Cummer is planning to install a low-light, high-speed camera to capture gigantic jet images in color, which could provide additional information about chemical processes and temperatures inside the phenomenon. (ANI)

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