Nearly a week into devastating wildfires in France, officials said that firefighters had encountered a pyrocumulonimbus — a “fire cloud,” or a thundercloud created by intense heat. The phenomenon can spark new blazes and is “unprecedented in France,” officials said. Here's what to know.

nyti.msHeat From France’s Wildfires Creates a ‘Fire Cloud,’ or PyrocumulonimbusA pyrocumulonimbus — a thundercloud created by intense heat — is a phenomenon that can spark new blazes and is “unprecedented in France,” officials said.