The Hunga Tonga volcano eruption continues to break records. Its latest? The highest altitudes that lightning has ever been known to start.
The plume from the eruption produced lightning flashes that kicked off 20 to 30 kilometers above sea level, researchers report in the June 28 Geophysical Research Letters.
The explosion of the underwater Hunga Tonga-Hunga Ha’apai volcano, in the island nation of Tonga, occurred in January 2022. The newly reported stratosphere-scraping flashes join the eruption’s growing list of standout stats, which include producing the greatest concentration of lightning ever detected and a plume so tall it touched space as well as generating a tsunami the size of the Statue of Liberty (SN: 12/13/22; SN: 8/29/22).
Volcanic lightning occurs when colliding ash particles make static electricity. To estimate the altitudes of the eruption’s flashes, volcanologist Alexa Van Eaton and colleagues analyzed data from ground-based lightning detection networks, infrared maps of lightning captured by satellites and satellite images of the plume.
Though some types of lightning can extend much higher into the atmosphere, a lightning flash doesn’t typically get started more than 20 kilometers above sea level. That’s because the air pressure is too low to form “leaders,” the channels of hot plasma that make up the lightning typically seen in thunderstorms.
The rising plume from the eruption may have raised the air pressure enough to create lightning at unusually high altitudes, says Van Eaton, of the U.S. Geological Survey’s Cascades Volcano Observatory in Vancouver, Wash.
In the Hunga Tonga eruption data, “we’re seeing stuff that we’ve never seen before,” says Jeff Lapierre, a study coauthor and principal lightning scientist at the company Advanced Environmental Monitoring, based in Germantown, Md. “Hunga has completely changed the way we think of how natural events can change the atmosphere, and the environment where we thought lightning could exist.”
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