In the devastating wildfires in France, officials said that firefighters had encountered a dangerous phenomenon that many of them had not seen before: a pyrocumulonimbus, or “fire cloud.”
These large, fire-fueled thunderstorms, also known as pyroCbs, are created by intense heat from large blazes or volcanic eruptions. They produce lightning and burning embers that can spark more fires, and they generate high and unpredictable winds that fan the flames and spread the embers. But they rarely bring rain.
One pyrocumulonimbus generated more blazes over the weekend in one of the hardest-hit areas of France, Marc Vermeulen, the director of fire and emergency services in the Gironde region, said at a news briefing on Sunday.
“While this type of fire occurs regularly in Canada and Australia, it is unprecedented in France,” Lt. Col. Eric Brocardi, a spokesman for the National Firefighters Federation of France, told Agence France-Presse.
“The fire became extremely virulent and unpredictable again generating its own wind and spreading erratically toward the Bordeaux metropolitan area,” Laurent Nuñez, France’s interior minister, also said on social media.
Wildfires are so hot they can sometimes create their own weather systems. The smoke from the fires acts as a plume of heat rising fast into the atmosphere, according to Britain’s Royal Meteorological Society. That chimney effect sucks in air at ground level, feeding the blazes oxygen and pushing them into new terrain.
As the hot air rises, it expands and cools, causing its moisture to condense. The water vapor and ash particles combine to form a gray or brown cloud that can then develop into a pyrocumulonimbus (pyro means “fire” in Greek) storm cloud.
In the Gironde region, 103,000 acres have burned, according to officials, and 220,000 people have been asked to evacuate from Gironde and the neighboring Landes region.
The pyrocumulonimbus phenomenon presents extreme challenges for firefighters.
“These fire-generated clouds are linked to extreme fire behavior that impedes firefighting efforts and can devastate communities,” according to NASA, which emphasized the need to better understand the clouds “given the ongoing and projected increases in fire activity and severity.”
Ephrat Livni contributed reporting.
The post Firefighters in France Encounter a ‘Fire Cloud’ appeared first on New York Times.
