‘Giant plane’ lifted 50 miles into space by thunderstorm (Chris Holmes)
A huge lightning bolt that shot 50 miles into space above a thunderstorm has offered new insights into mysterious “giant jets” that carry huge amounts of electrical charge.
Scientists estimate that up to 50,000 “giant jets” can occur each year – and new research may help explain why they shoot up into space rather than down to earth.
The giant plume rises from a thunderstorm in Oklahoma and is the most powerful ever studied.
Normal lightning carries less than five coulombs of electric charge: the giant jet moved about 300 coulombs of electric charge into the ionosphere, the lower end of space.
The upward ejection included structures known as “leaders” that were 4400C, as well as jets of cooler plasma.
Correspondent Levi Boggs, a researcher at the Georgia Tech Research Institute (GTRI), said: “We were able to map this giant jet in three dimensions with really high-quality data.
“We were able to see many high-frequency (VHF) sources above the cloud top that had not been seen before with this level of detail.
“Using satellite and radar data, we were able to learn where the very hot leading part of the ejection was located above the cloud.”
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Steve Coomer, a professor of electrical and computer engineering at Duke, uses the electromagnetic waves that lightning emits to study the powerful phenomenon.
He operates a research facility where sensors resembling conventional antennas are lined up in an otherwise empty field, waiting to pick up signals from local storms.
Cummer said: “The VHF and optical signals have definitively confirmed what researchers suspected but had not yet proven: that the VHF radio from lightning is emitted by tiny structures called streamers, which are at the very top of the developing lightning as it progresses. -the strong 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 are rare.
Boggs learned about the Oklahoma event from a colleague who told him about a giant plane that was filmed by a citizen scientist who had a camera running in low light 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) sites and accessible to instruments on NOAA’s Geostationary Operational Environmental Satellite (GOES) network satellites .
Boggs found that data from these systems was available and worked with colleagues to collect it for analysis.
Boggs explained, “The detailed data show that these cold streamers begin their propagation just above the cloud top.
“They propagate all the way down to the lower ionosphere up to an altitude of 50-60 miles, making a direct electrical connection between the top of the cloud and the lower ionosphere, which is the lower boundary of space.”
Why do giant jets shoot a charge into space? The researchers speculate that something may be blocking the flow of charge downward or to other clouds.
Footage of the Oklahoma event showed little lightning activity from the storm before it launched the record-breaking giant jet.
Boggs said: “For whatever reason, there is usually a suppression of cloud-to-ground ejections.
“There’s a build-up of negative charge, and then we think the conditions at the top of the storm weaken the uppermost layer of charge, which is normally positive.” In the absence of lightning discharges that 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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