French wildfire created country's 1st recorded pyrocumulonimbus cloud, igniting more fires

By — Thomas Adamson, Associated Press Thomas Adamson, Associated Press Leave your feedback Share Copy URL https://www.pbs.org/newshour/world/french-wildfire-created-countrys-1st-recorded-pyrocumulonimbus-cloud-igniting-more-fires Email Facebook Twitter LinkedIn Pinterest Tumblr Share on Facebook Share on Twitter French wildfire created country's 1st recorded pyrocumulonimbus cloud, igniting more fires World Jul 27, 2026 5:28 PM EDT PARIS (AP) — A wildfire in southwest France grew so powerful that its smoke column became a thunderstorm, generating lightning that struck the ground and ignited new fires beyond the original blaze, French officials said. READ MORE: France says enormous wildfire that forced 220,000 people to flee has stopped growing Put another way, that means the inferno was no longer simply being propelled by the weather. It was making its own. The thundercloud also produced violent, erratic winds capable of driving the flames in new directions. The phenomenon, called a pyrocumulonimbus, or pyroCb, is rare in Europe and more commonly documented in North America and Australia, where it occurs only over some of the most extreme fires. France's national firefighters federation said it had never before recorded one in the country. The blaze erupted near Saumos on July 22 and has since burned more than 420 square kilometers (162 square miles) of forests and scrubland, damaged or destroyed more than 240 homes and forced 220,000 people to evacuate in Gironde. At about 6:20 p.m. Friday, two days after the fire began, the departmental fire and rescue service said it had generated a pyrocumulonimbus. The cloud weakened overnight as humidity rose, then formed again several times. An electrified black thundercloud Repeatedly, heat and smoke have surged upward into a vast black thundercloud, electrified and lit from within. "Imagine a campfire so large and hot that the smoke rising off it turns into a storm-like cloud," said Theodore M. Giannaros, a fire meteorologist at the National Observatory of Athens. "That is a pyroCb — a storm cloud born from the intense heat that a wildfire produces." It takes more than a big fire. There is no set temperature at which one forms, Giannaros said; what is needed is the kind of atmosphere that breeds dry thunderstorms — very hot, very dry air near the ground, with cooler and moister air above it. Hot air loaded with smoke and moisture then rises rapidly from the flames. As it climbs and cools, water vapor condenses around particles of ash. Above the freezing level, droplets become ice crystals whose collisions separate electrical charges, as in an ordinary thunderstorm. Lightning and more destruction follow Beneath this storm lies a landscape already primed to burn. The cloud then amplifies the disaster that created it. Rising air pulls powerful winds toward the fire, while downdrafts punch gusts back to the surface. Those shifts can turn the flames, divide them into several fronts or send them racing in a ne