Q: You sometimes hear of a “firenado.” What is it?
A: Firenadoes are whirlwinds of flame, says Brent McRoberts of Texas A&M University. “They are also called fire devils or fire whirls, and they are whirlwinds of flame that sometimes occur when intense heat and gusty wind conditions combine to form a tornado-like structure of fire. The formation is a result of the strong upward motion of very hot air, which leaves an area of lower pressure at the base of the fire. Strong winds swirl around this low pressure area and produce a core that can be 3 to 5 feet wide, can be 100 feet high or more, and can reach up to 2,000 degrees.”
Q: Where do they occur most often?
A: They seem to appear most often in hot and arid parts of the country, but they can occur almost anywhere there is a big wildfire, McRoberts adds. “They are frequently seen in Australia and parts of Africa on very hot days,” he notes. “There appears to be very few photos of them, but we know that a large one occurred in Canberra in 2003, and it’s believed a large firenado was the result of a big earthquake that hit Japan in 1923 that caused numerous fires in parts of Tokyo and eventually killed thousands. A large one is also believed to have formed in San Luis Obispo, California, in 1926 and killed several residents. People who have been near a firenado say the sound of it is deafening and it resembles the noise from a jet engine.”
Weather Whys is a service of the Department of Atmospheric Sciences at Texas A&M University