It had hundreds of times more power than an atomic bomb. In 2022, the Hunga volcano triggered the largest thunderstorm in history. It spewed 9.5 cubic kilometers of molten rock and vaporized 146 teragrams of water. That’s enough to fill 58,000 Olympic-sized swimming pools.
The mushroom cloud rose 57 kilometers high. Halfway into space. A huge ring of lightning appeared, expanding from the epicenter of the eruption at about 180 kilometers per hour. It generated a staggering 2,600 lightning bolts per minute at its peak. The largest thunderstorm in history.
Water in the atmosphere
An average low-intensity thunderstorm may have one lightning flash per minute. In large supercells, those that cause tornadoes, the frequency of lightning is in the hundreds per minute. In the Hunga event, something superlative occurred. Lightning was recorded at a height several kilometers higher than ever thought possible. Researchers attribute this to the copious amounts of warm seawater injected into the atmosphere.
Another unusual feature of the Hunga eruption is gravity waves. They are produced when a trigger (such as extremely hot volcanic gases) pushes air up or down. They can be more buoyant than the surrounding atmosphere, creating distinct layers, such as oil and water.
A normal object would fall straight down after reaching its maximum height. But in this case the plume is trapped above the layer of normal atmosphere. As it falls, gravity forces the plume horizontally, creating waves like ripples in a pond. The water vapor cools to form hail. Chunks of ice accumulate static electricity as they rub against each other. This produces a higher frequency of lightning and thunder.
Volcanic mystery
But many mysteries remain. There is a point at which the ring of lightning seems to dissipate. And then the doughnut hole fills up again with thousands of flashes. “We don’t have any answers” for the doughnut hole, the researchers say. “For that we will probably have to wait for many more eruptions.”
