California’s largest wildfire of the year is tearing through the Mojave Desert and creating dangerous spinning columns of flames known as fire whirls.
These twirling vortices are dangerous for crews battling the wildfire, because they can spread embers over long distances and spark fires beyond the main blaze’s edge, per a Facebook post from the Mojave National Preserve. The whirls can also rapidly change direction, making it difficult to anticipate where they will go next.
“These fire whirls are similar to dust devils but are specifically associated with the heat and energy released by a wildfire,” writes the preserve. “They can range in size from a few feet to several hundred feet in height, and their rotational speed can vary widely.”
The record-setting blaze, called the York Fire, is 93,078 acres in size and 85 percent contained as of Friday morning. Fueled by dry and windy weather, the wildfire is engulfing the landscape and sending clouds of smoke over inhabited areas, such as Las Vegas.
Fire whirls are created as super-hot air quickly rises from a blaze, per the National Oceanic and Atmospheric Administration (NOAA). As the air moves upward, it leaves behind empty space, and surrounding air rushes in to fill it. This rapid movement leads to powerful winds that can create a spinning column of air.
While the term fire whirl is sometimes used interchangeably with fire tornado (or ‘firenado’), some researchers say the scale of the two phenomena are different—though not all agree on exactly what distinguishes the two.
“Fire tornadoes are…the larger version of a fire whirl, and they are really the size and scale of a regular tornado,” Jason Forthofer, a firefighter and mechanical engineer at the U.S. Forest Service’s Missoula Fire Sciences Laboratory in Montana, told NPR’s Nick Mott in 2021.
According to a 1978 report from NOAA, fire whirls average 33 to 100 feet in diameter, with rotational velocities of 22 to 67 miles per hour. These whirls rise to the level of a fire tornado when they average 100 to 1,000 feet in diameter and spin at up to 90 miles per hour. Even larger is the fire storm, which the agency describes as “extremely violent.” These have been observed to be 1,000 to 10,000 feet wide, with winds in excess of 110 miles per hour.
In 2018, a monstrous 1,000-foot-diameter swirling fire vortex was caught on video during California’s Carr wildfire. According to researchers, this whirl had winds of around 143 miles per hour and reached temperatures up to 2,700 degrees Fahrenheit. The spinning blaze killed a firefighter who was helping to battle the flames.
Fire whirls can be incredibly deadly, especially in urban settings. In 1923, an earthquake ignited flames in Tokyo, leading to what was likely the most destructive fire whirl on record. Researchers estimate the vortex killed 38,000 people in less than 15 minutes.
NPR’s Joe Hernandez reports that recently, documentation of fire whirls and tornadoes has spiked—though it’s unclear whether they are becoming more common as climate change leads to more intense wildfires, or whether people are simply recording the phenomena more frequently.
The cause of the current, York Fire is still under investigation, though officials say it started on private land within the Mojave preserve. On Sunday, the flames crossed state lines into Nevada. The fire has charred iconic Joshua trees and blackbrush scrub, which are unlikely to regrow, though conservationists are trying to plant new trees, per the Associated Press.
“It will change the habitat, possibly permanently,” Ileene Anderson, a senior scientist at the Center for Biological Diversity, tells the publication.