CNA Explains: What are fire clouds, and why are they making Europe's wildfires more dangerous?

Europe's wildfires are becoming more dangerous due to a rare phenomenon: pyrocumulonimbus clouds, also called "fire clouds." These towering storm clouds form when the intense heat of a massive wildfire acts like a chimney, rapidly sending hot air, smoke, ash, and water vapor high into the atmosphere. As this plume rises into cooler air, moisture condenses, creating a mushroom-shaped cloud that resembles a thunderstorm. This process generates powerful, erratic winds around the blaze, pushing flames in unpredictable directions and making containment extremely difficult. The clouds can also produce lightning, potentially igniting new fires far from the main blaze. Furthermore, the strong updrafts can carry burning embers miles away, dropping them to start new fires across roads, rivers, and firebreaks. This "fire behavior" makes predicting and controlling the spread of wildfires exceptionally challenging. Fire clouds have been linked to some of the world's most destructive wildfires, including those in Australia and California. The current situation in Europe has heightened concerns about their impact on already severe blazes.

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These thunderstorms generated from the fire plumes can lead to even more erratic conditions, which are very, very difficult to contain.