The eruption of the Hunga Tonga volcano continues to break records. His last? The greatest height from which lightning has ever been known.
The plume from the eruption caused flashes of lightning that began at an altitude of 20-30 kilometers above sea level, researchers reported in Geophysical Research Letters from June 28.
The explosion of the underwater volcano Hunga Tonga-Hunga Ha’apai in the island nation of Tonga occurred in January 2022. The recently reported stratospheric flares join a growing list of outstanding eruption statistics that include producing the largest concentration of lightning. ever discovered, and the plume is so high that it touched space, and also caused a tsunami the size of the Statue of Liberty.
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Volcanic lightning occurs when ash particles collide, creating static electricity. To estimate the height of the eruption’s flares, volcanologist Alexa Van Eaton and colleagues analyzed data from ground-based lightning detection networks, infrared lightning maps taken by satellites, and satellite images of the plume.
Although some types of lightning can travel much higher in the atmosphere, a lightning flash usually does not start above 20 kilometers above sea level. That’s because the air pressure is too low to form “leaders,” the channels of hot plasma that form the lightning typically seen in thunderstorms.
The rising plume from the eruption could have increased air pressure enough to produce lightning at extremely high altitudes, says Van Eaton of the USGS’s Cascade Volcano Observatory in Vancouver, Washington.
In the Hunga Tonga eruption data, “we’re seeing things we’ve never seen before,” said Jeff Lapierre, co-author of the study and principal lightning researcher at Advanced Environmental Monitoring, a Germantown, Maryland-based company. “Hunga completely changed our understanding of how natural events can change the atmosphere and environment where we thought lightning could exist.”
