Lightning strikes can be both thrilling and terrifying to witness from the ground, but what’s even more amazing is that these intense bolts of plasma can sometimes erupt in the opposite direction, zigzagging up into space in dazzling displays known as gigantic jets.
Scientists led by Levi Boggs, a research scientist at the Georgia Tech Research Institute, have described the strongest gigantic jet ever seen, which erupted from a cloudtop in Oklahoma and darted 50 miles above the Earth’s surface, delivering the largest charge transfer to space on record.
Unlike most lightning bolts, which carry less than five coulombs (a measure of charge), this jet delivered a whopping 300 coulombs to the ionosphere, the lowest part of space, when it struck on May 14, 2018. That is nearly double the previous largest charge by a massive jet and is on par with the largest cloud-to-ground strokes ever recorded.
According to a study published last week in Science Advances, the jet was captured on film by a nearby citizen scientist using a low-light camera, as well as other instruments on the ground and in space, revealing never-before-seen details about these mysterious upward strikes that have “broad implications to lightning physics beyond that of gigantic jets.”
“Observations of gigantic jets are extremely rare—only a few per year, if that,” Boggs explained in an email. “As a result, I take advantage of any opportunity to study them, because capturing them with dedicated field campaigns is extremely difficult.” I was told about this video by chance, and fortunately, the event in the video was also observed by a ground-based radio mapping network and optical instruments in geostationary orbit.”
The jet has perplexed scientists such as Boggs because it emerged from “unusual circumstances” in a “unique thundercloud,” according to the study. Most massive jets occur in tropical environments and near areas of a storm that are strongly convective, but this one occurred in a weakly convective area.
“Normally, gigantic jets occur near the equator from tropical storms with really tall cloud tops (18 km) that penetrate into the stratosphere and associated cloud top turbulence,” Boggs explained. “However, this event occurred in the middle of the continental United States and had relatively low cloud tops (14 km) with little cloud top turbulence.”
“There was no lightning activity in the parent storm cell prior to the gigantic jet, which has never been observed before,” he continued. “This allowed the parent storm to accumulate a significant amount of electric charge, allowing the gigantic jet to transfer the most charge to the ionosphere on record (300 coulombs).”
The citizen scientist video was captured from the ground in Hawley, Texas, just across the state line, but the jet was also detected by a sophisticated mapping system for very high frequency (VHF) radio signals caused by lightning bolts, two Next Generation Weather Radar (NEXRAD) stations, and NOAA’s Geostationary Operational Environmental Satellite (GOES) network.
Boggs and his colleagues sifted through this opportune avalanche of information in search of clues about the origin and dynamics of the Oklahoma jet. The findings supported theories about the behavior of key plasma components of lightning bolts, known as streamers and leaders, which have temperatures of 400 degrees Fahrenheit and 8,000 degrees Fahrenheit, respectively.
“The combined 3D radio and optical data provide critical insight into the plasma nature of gigantic jets,” the researchers wrote. “Moreover, the radio and optical data provide the first conclusive evidence that the VHF observed by lightning networks is produced by streamers ahead of the leader.”
Despite the fact that the Oklahoma jet provided this incredible glimpse into an unrivaled jet, many questions about these enigmatic events remain. Solving these mysteries is an intriguing scientific endeavor in and of itself, but it also has practical implications because massive jets could disrupt spacecraft operations.
“Because these events connect with the lower edge of space and transfer charge to that region, they may have effects on space weather that affect communications and electromagnetic signals between the ground and satellites in orbit,” Boggs explained. He also stated that while it is possible for the jets to collide with an aircraft, it is extremely unlikely because pilots avoid flying over thunderclouds.
Nobody knows how many of these jets are launched into space each year, with estimates ranging from 1,000 to 50,000, leaving plenty of room for future discoveries. Boggs and his colleagues hope to see more of these brilliant events, which could potentially illuminate the skies with gamma rays, the most energetic form of light.
“Our findings indicate that as the discharge escapes the cloud, the electric field at the tip should be extremely large, possibly large enough to produce gamma rays,” Boggs concluded. “Terrestrial gamma ray flashes (TGFs) have been observed from lightning for several years now, but never from a massive jet.” Our findings suggest that massive jets may also produce TGFs.”