The mystery of “giant jet” lightning 100 times more powerful than normal

The mystery of "giant jet" lightning 100 times more powerful than normal

‘Gigantic jet’ soared 50 miles into space from storm (Chris Holmes)

A huge lightning bolt that soared 50 miles into space above a storm has offered new insights into , which carry large amounts of electrical charge.

Scientists believe that up to 50,000 “giant jets” can occur each year, and new research may help explain why instead of descending toward the ground.

The gigantic jet emerged from a storm in Oklahoma and is the most powerful ever studied.

Normal lightning carries less than five coulombs of electrical charge – the giant jet moved about 300 coulombs of electrical charge into the ionosphere, the lower edge of space.

The upward discharge included structures known as “leaders” that had a temperature of 4,400 °C, as well as streamers of colder plasma.

Corresponding author Levi Boggs, a research scientist at the Georgia Tech Research Institute (GTRI) said, “We were able to map this giant jet in three dimensions with high-quality data.

“We were able to see very high frequency (VHF) sources above the cloud top, which had not been seen before in this level of detail.

“Using satellite and radar data, we were able to figure out where the very hot leading part of the discharge was located above the cloud.”

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Steve Cummer, a professor of electrical and computer engineering at Duke, uses the electromagnetic waves emitted by lightning to study the powerful phenomenon.

It operates a research site where sensors that look like conventional antennas are set up in an otherwise empty field, waiting to pick up signals from local thunderstorms.

Cummer said: “The optical and VHF signals definitively confirmed what researchers had suspected but not yet proven: that the VHF radio in lightning is emitted by small structures called streamers that lie at the tip of the developing lightning, while which flows the strongest electric current. significantly behind this tip in an electrically conductive channel called the leader.”

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Giant jets have been observed and studied for the past two decades, but because there is no specific observing system to look for them, detections have been rare.

Boggs learned about the Oklahoma event from a colleague, who told him about a giant jet that had been photographed by a citizen-scientist who had a low-light camera running on May 14, 2018.

Fortunately, the event occurred at a location with a nearby VHF lightning mapping system, within range of two Next Generation Weather Radar (NEXRAD) locations, and accessible to instruments on satellites in the satellite network ·NOAA Geostationary Operational Environmental Surveys (GOES).

Boggs determined that data from these systems was available and worked with his colleagues to gather it for analysis.

Boggs explained: “The detailed data showed that those cold streamers start their propagation just above the cloud top.

“They propagate down into the lower ionosphere up to an altitude of 50 to 60 miles, making a direct electrical connection between the top of the cloud and the lower ionosphere, which is the lower edge of space.”

Why do giant planes charge into space? The researchers speculate that something may be blocking the flow of charge down or to other clouds.

Records of the Oklahoma event show little lightning activity from the storm before it fired the record-breaking jet.

Boggs said: “For whatever reason, there is usually a suppression of downloads from the cloud to the ground.

“There’s a build-up of negative charge, and then we think the conditions at the top of the storm weaken the upper layer of charge, which is usually positive. In the absence of the lightning discharges we normally see, the giant jet can relieve the build-up of excess negative charge in the cloud.”

Estimates of the frequency of giant jets range from 1,000 per year to 50,000 per year.

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