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      • Nick Nauslar: Well, the easy answer is: Any sort of weather that ignites and/or helps spread fire. Stronger winds; low, relative humidity; unstable atmospheric conditions; and thunderstorms all fall under the umbrella of fire weather.
      www.noaa.gov/stories/ask-scientist-how-can-weather-spark-and-spread-wildfires
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  2. Jan 24, 2019 · Scientists are tracking an increase in a little-known phenomenon in which intense wildfires can spawn their own thunderstorms, known as pyroCbs. Lightning from these storms can spark additional blazes far away and send plumes of smoke and aerosols into the stratosphere.

    • Overview
    • How firestorms get started
    • Firestorm damage
    • Fire weather and climate change

    As climate change stokes larger and more intense wildfires, firestorms are likely to become more common. Here’s why they occur and what makes them so dangerous.

    Weather and wildfires share a close relationship. Certain weather conditions are known to ignite wildfires: High temperatures and low humidity dry out the landscape, lightning strikes can spark a flame, and fast-moving winds spread flames across nearby desiccated land.

    But wildfires also spawn their own weather systems, including pyrocumulonimbus clouds—which NASA has called the “fire-breathing dragon of clouds” for the thunderbolts they hurl at Earth, fueling further blazes and sometimes even fire tornadoes.

    Fire weather has contributed to the scale of several historic conflagrations, including the 2009 Black Saturday bushfires that burned more than a million acres across Australia, and the wildfires across the West Coast of the United States in 2020. Here’s what causes firestorms—and why they’re becoming more common in a warming world.

    Firestorms form through a convective process, in which heat rises through the air. When a column of moist air over a fire becomes intensely hot, it rushes up into the atmosphere where it cools and condenses into droplets, creating fire clouds called pyrocumulus clouds. Unlike the fluffy white cumulus clouds that also are created by convection, fire clouds are grayish or brown because of the ash, smoke, and particulate matter that get swept into the updraft. The tops of these clouds can reach nearly six miles high.

    Left:

    Firefighters battle blazes from the Hog fire, which exploded across more than 9,500 acres of land in Northern California, near Susanville, on July 20, 2020. The fire was so intense it produced a pyrocumulonimbus cloud and fire whirls.

    Right:

    Firefighters look on as a thunderstorm cell draws in a smoke column from the Hog fire on July 21, 2020. Alhough pyrocumulonimbus clouds rarely produce precipitation, this one eventually evolved into a hail storm that extinguished some of the flames—and fanned others.

    Photographs by Josh Edelson, AFP/Getty Images

    Fire weather helped fuel some of the devastating wildfires in recent history. In 2009, the Black Saturday bushfires in the Australian state of Victoria generated clusters of pyroCb clouds that stretched more than nine miles high and ignited new fires that contributed to the fire’s spread across more than a million acres of land. The Black Saturday fires killed 173 people, the greatest loss of life from fire since Australia’s colonization in 1788.

    2:57

    Climate 101: Wildfires

    What are wildfires and how do they start? Learn how we can prevent destructive wildfires, and how we can manage wildfires to improve the health of forests.

    In 2017, an even bigger wildfire in the forests of British Columbia produced five fire thunderstorms nearly simultaneously. They blew smoke up to 14 miles into the stratosphere as black carbon in the smoke absorbed the sun’s energy and heated the plume, making it rise faster and farther. Multiple studies have shown that the plumes were comparable to those of a moderate volcanic eruption and remained in the atmosphere for almost nine months.

    In the United States, California has also seen several intense pyrocumulonimbus events. During the Carr fire near Redding in July 2018, a fire tornado spinning at speeds of up to 143 miles an hour was responsible for four of the eight deaths associated with the fire. In August 2020, several possible fire tornadoes were reported in Northern California during a record-breaking fire season rife with firestorms.

    As climate change stokes bigger and more intense wildfires, scientists believe the planet will experience a rise in firestorms. In 2019, Australia saw as many fire-generated storms as it had seen in the 20 preceding years. On September 7, 2020, smoke from a pyrocumulous cloud near Fresno, California, shot 10 miles into the stratosphere, a record for a fire in North America that likely released significant carbon emissions.

    In fact, scientists believe these firestorms are responsible for “a huge volume” of the pollutants in the upper atmosphere. But there’s still much that’s unknown about how firestorms might contribute to climate change, including whether their plumes damage the ozone layer that protects Earth from ultraviolet radiation and whether they might actually have a temporary cooling effect on the planet by blocking sunlight—a phenomenon seen in volcanic eruptions. Answering these questions will be key to understanding the true consequences of firestorms in a warming world.

    • Amy Mckeever
    • 3 min
  3. May 14, 2021 · A pyroCb is a thunderstorm generated by fire that creates its own positive feedback loops, including winds, lightning and sometimes deadly downdrafts that spread the fire outwards.

  4. Jun 17, 2024 · But climate change is making the weather conditions needed for wildfires to spread more likely, the IPCC says. Extreme, long-lasting heat draws more moisture out of soils and vegetation.

  5. Stronger winds; low, relative humidity; unstable atmospheric conditions; and thunderstorms all fall under the umbrella of fire weather. Q: How does the weather start wildfires and help them spread? NN : Lightning striking a tree and igniting it is the most common weather cause for wildfires.

  6. Aug 1, 2024 · Wildfire blowups, fire whirls, towering thunderstorms: When fires get large and hot enough, they can actually create their own weather. In these extreme fire situations, firefighters’...

  7. Aug 2, 2024 · Wildfire blowups, fire whirls, towering thunderstorms: When fires get large and hot enough, they can actually create their own weather. In these extreme fire situations,...

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