from the explosion of the volcano the largest lightning storm in history - Corriere.it

from the explosion of the volcano the largest lightning storm in history - Corriere.it


Of Paolo Virtuani

Recorded over 192 thousand flashes. At the peak reached 2,615 flashes in one minute: some reached up to 30 kilometers in height

On January 15, 2022 the explosion of the underwater volcano Hunga Tonga, in the Pacific, has established some absolute records. Not only was it the strongest explosion in the last 140 years, it has the record of the strongest winds ever recorded (725 kilometers per hour) below 200 kilometers high, also the shock wave went around the world and it was also recorded by barometers in Italy, finally generating a tsunami that devastated the main island of the archipelago and an ash cloud that reached a height of 58 km.

The primacy of lightning

Now it is known that Hunga Tonga it also generated the largest lightning storm ever recorded: over 192,000 lightning strikes (for a total of almost 500,000 electrical impulses - in fact, several impulses can be developed during a single lightning strike, ed), with a peak of 2,615 flashes in one minute. Some of these flashes developed at a height of between 20 and 30 kilometers as had never been observed before and reached a distance of 250 km from the volcano. The study was published in Geophysical Research Letters
. The eruption triggered a supercharged lightning storm never seen before, said Alexa Van Eaton, a volcanologist with the United States Geological Survey (USGS) who led the analysis. Hunga Tonga was the first Freatoplinian eruption observed live, previously this category of eruptions was known only in geological sequences.

Volcanic lightning

Lightning during volcanic eruptions (they were also observed in the eruption of Vesuvius in 79 AD) are caused by the electrostatic energy of the ash and lapilli particles fired into the atmosphere. In the case of Hunga Tonga the mega lightning storm was amplified by the explosion below sea level in shallow water. The molten lava was vaporized upon contact with water and charged with static electricity in collisions with ashes, with evaporated and supercooled water in the upper atmosphere, and with hail particles that developed at high altitudes. The study of the flashes also demonstrated that the eruption lasted 11 hours in four distinct phases, much longer than the two hours observed by optical instruments. Another peculiarity never observed before were the rings of concentric lightning pulsating on the volcano, a phenomenon that has never been seen in weather storms. Single circular flashes had been observed, but never in concentric rings.

June 22, 2023 (change June 22, 2023 | 2:49 pm)



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