• inshallah2 [none/use name]
    ·
    3 years ago

    Emphasis mine. Jesus fuck...

    The Bootleg Fire Is Now Generating Its Own Weather - The New York Times

    Mr. Redman said that nearly every day the fire had created tall updrafts of hot air, smoke and moisture called pyrocumulus clouds, some of them reaching up to 30,000 feet. One day, he said, they saw one of these clouds collapse, which can happen in early evening when the updraft stops.

    "All that mass has to come back down," he said, which forces air at the surface outward, creating strong, gusty winds in all directions that can spread a fire. "It's not a good thing."

    Last Wednesday, though, conditions led to the creation of a larger, taller cloud called a pyrocumulonimbus, which is similar to a thunderhead. It likely reached an altitude of about 45,000 feet, said Neil Lareau, who studies wildfire behavior at the University of Nevada, Reno.

    Like a thunderhead, the huge cloud spawned lightning strikes, worrying firefighters because of their potential to start new fires. It may have also brought precipitation.

    "Some of these events rain on themselves," said John Bailey, a professor of forestry at Oregon State University.

    Rain can be a good thing, by dampening some of the fuels and helping slow the fire. But by cooling the air closer to the surface, rain can also create dangerous downdrafts, Dr. Lareau said.

    There have also been reports of fire whirls, small spinning vortexes of air and flames that are common to many wildfires and are often inaccurately described as fire tornadoes. Fire whirls are small, perhaps a few dozen feet in diameter at their largest, and last for a few seconds to a few minutes.

    But Dr. Lareau said there were some indications that the Bootleg Fire might have created an actual fire tornado, which can be several thousand feet in diameter, have wind speeds in excess of 65 miles an hour, extend thousands of feet into the air and last much longer. "It looks like it's been producing some pretty significant rotation," he said.

    Fire tornadoes occur as a plume of hot air rises within a fire, which draws more air from outside to replace it. Local topography and differences in wind direction, often caused by the fire itself, can impart a spin to this in-rushing air, and stretching of the air column can cause it to rotate faster, like a figure skater pulling her arms in to increase her spin.