Key facts
- Wildfires in France are generating "pyrocumulonimbus" clouds, described as fire-generated thunderstorms.
- These clouds form when intense heat from fires rapidly lifts air, smoke, ash, and water vapor.
- The phenomenon can spread embers over long distances and spark new fires, complicating firefighting efforts.
- Record heatwaves and dry conditions across Europe have exacerbated wildfire risks.
- Scientists anticipate that climate change will lead to more frequent occurrences of these fire clouds.
Wildfires in France have created "pyrocumulonimbus" clouds, a phenomenon scientists describe as fire-generated thunderstorms, which are making the blazes more dangerous and unpredictable. These clouds form when the intense heat from a large wildfire rapidly lifts air, smoke, ash, and water vapor high into the atmosphere. As this air cools, water vapor condenses, and if the fire is powerful enough and the atmosphere unstable, it can grow into a towering cumulonimbus cloud, similar to those that produce thunderstorms.
The turbulent winds generated by these fire clouds can propel embers in all directions, leading to the rapid spread of fires and the ignition of new blazes, sometimes miles ahead of the main fire front. French firefighting authorities have linked this phenomenon to the wildfires near Bordeaux, noting it has not been previously observed in the country. The situation in Gironde remains challenging, with a new heatwave forecast to bring temperatures as high as 40C (104F) later this week, and officials warn the wildfire could burn for many weeks.
Across Europe, intense heatwaves and minimal rainfall have created dry conditions highly susceptible to wildfires, impacting regions like France, Spain, and the UK. Scientists predict that climate change will likely increase the frequency and intensity of such fire-generated thunderstorms. Similar events have been documented in Australia, where embers landed up to 30km ahead of a fire front, and in California in 2021, where fires generated clouds that towered over the blazes.