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Title:'Fire-breathing dragon clouds’: a wildfire-fueled phenomenon explained
Date:8/6/2022 1:00:06 AM

Feared pyrocumulonimbus clouds, akin to fire-triggered thunderstorms, are becoming more frequent as blazes rage

Nasa calls them the “fire-breathing dragon of clouds”.

Aerial images of the McKinney fire taken this week captured an increasingly common phenomenon: a nearly 50,000ft plume known as a pyrocumulonimbus.

The fire, which is raging nearly uncontained in California’s Klamath national forest, is just the latest this year to produce the clouds. They are akin to fire-triggered thunderstorms, explained Derek Mallia, a researcher at the University of Utah who recently co-authored a paper showing how smoke plumes are getting taller, and they are of deep concern to firefighters.

Typically, thunderstorms are initiated by large-scale storm systems like a low pressure zone or a cold front. But if a fire is large enough and there is enough moisture in the atmosphere, it can create its own thunderstorm where smoke mixes with the resulting thunderstorm cloud. “Essentially, the fire is creating its own weather,” Mallia said.

Pyrocumulonimbus clouds are feared for several reasons. When they form above fires, the clouds can make the blaze below spread even faster. Sometimes they can also create their own lightning, which can spark more fires. Fire-triggered clouds tend to be drier and produce less rain, Mallia explained. “This can be problematic as pyrocumulonimbus clouds can produce a lot of wind, which can result in unpredictable fire behavior underneath the cloud and even cause new fires from lightning strikes.” That’s what happened in British Columbia during the summer of 2021, when one fire generated 700,000 flashes of lightning, as many as the province typically gets in one year.

They also can cause fires to move in erratic ways, because they create a vacuum between the cloud and the ground. The hotter a wildfire burns, the more rising air it produces, said David Peterson, a meteorologist at the US Naval Research Laboratory,...

Organization:Guardian - Climate Change
Date Added:8/6/2022 6:37:04 AM