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Fire Weather

Fire Weather

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 In another EarthDate, we talked about ways to prevent wildfires. Now, we’ll talk about what’s encouraging them. In a warming climate, the air holds more moisture. It draws more water from plants, making them drier and more combustible. Summers become longer, which extends the fire season and gives fire-prone lands more chances to burn. Expanding development also puts more people in fire zones. Human activity starts four out of five fires, which increases burned areas sevenfold. Drought across the West, intensified by development and agricultural water use, makes fires more likely. But one of the strongest contributors to fires are fires themselves. Wildfires, it turns out, can make their own weather—which causes them to spread. Two of California’s biggest fires last year produced devastating firestorms. Towering flames heat the air, creating a rapidly rising updraft, which pulls air into the base of the fire, feeding it with oxygen and increasing the intensity. These updrafts may eventually spiral into what’s called a fire whirl—essentially a tornado of flames, with winds up to 150 miles an hour. Meanwhile, smoke fills the air with particulates, on which water vapor can condense, forming thunderheads above fires that can produce lightning and start more fires. Scientists are now studying fire weather, and re-creating it in lab conditions, to better understand how to control wildfires once they begin.
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