However, we’re still in the dark about exactly how these huge electrical illuminations grow so long. Researchers believe that cloud size is one factor, because the larger the cloud system, the more potential there is for lightning flashes to occur within it. Also required, MacGorman adds, are certain “mesoscale processes – large scale wind flows that enable that system to be tied together to persist for a long time.”
So with the stage set by these monster clouds, what’s actually happening within them? “These megaflashes appear to be like a continuous sequence of discharges in very close succession,” said Christopher Emersic, a research fellow who studies thunderstorm electrification at the University of Manchester, in the UK.
He hypothesizes that if a cloud system is highly charged across a large area, a series of discharges can propagate through It like a line of falling dominoes. “If dominoes are all set up without too big a gap, one triggers another in a large series of topples. Otherwise it ‘fails’ and, in this case, you’ll get only a smaller spatial lightning event rather than a megaflash,” Emersic told Live Science.
The larger the parent cloud, the more opportunity there is for the discharge to continue propagating. “Hence why megaflashes could, in principle, be as large as the parent cloud, should the charge structure be conducive,” Emersic said.
That also means there are likely much bigger flashes out there than we’ve already seen. “Storms can get larger than [the ones we’ve measured from],” MacGorman said.
In other words, we still don’t know exactly how big the biggest lightning bolt could be.
despite the apocalyptic picture they paint, megaflashes aren’t necessarily more dangerous than regular lightning: “A spatially extensive flash doesn’t necessarily mean it carries more energy,” Emersic explained.
That said, because the cloud systems from which they originate are so vast, megaflash strikes can be difficult to predict.
“Such events can often lead to ground strikes far away” from the main lightning activity in the convective core, “Emersic said. “Someone on the ground could think the storm has passed, but be caught by surprise by one of these spatially extensive discharges seemingly from nowhere.”
It’s also possible that in a warming world, there might be an uptick in the types of storms that give rise to megaflashes, Emersic said. “And so indirectly, that can make the conditions more likely, increasing increasing their frequency.”
For now, though, megaflashes aren’t that common: MacGorman estimates that they make up only about 1% of lightning flashes overall. Nevertheless, researchers like him will go on hunting – and no doubt discovering – even bigger behemoths for us to marvel at.
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