Geline Salac

What are 'fire clouds', the ominous phenomenon seen in France?

Article (news)

fireclouds

Agence France-Presse

<p>PARIS, France - Firefighters battling devastating fires in France have had to contend with a new threat: immense fire clouds that create their own wind and even lightning that can spark fresh blazes.</p><p>Known as &quot;fire clouds&quot; or pyrocumulonimbus clouds, these ominous-looking thunderstorms are created by extreme wildfires and can exacerbate already extremely dangerous conditions.</p><p>This phenomenon, which is new to France, is yet another consequence of human-caused climate change, according to French researcher Jean-Baptiste Filippi, who studies wildfires.</p><p>As firefighters in southwest France struggle to bring a forest inferno under control before yet another heatwave descends on the country, Filippi told AFP about the phenomenon.</p><div><br/></div><div><strong>- What is a fire cloud? -</strong></div><div><br/></div><p>Filippi: It is a storm where a column of air forms above a fire.</p><p>It starts off as a cute little white cloud -- a cumulus cloud, which is formed because water vapour has turned into tiny droplets.</p><p>As the Sun heats the ground, the water vapour suddenly condenses. The cumulus becomes a much larger cloud, containing thousands of tonnes of suspended water.</p><p>Then, when the surrounding air has become heated enough, it forms a column with an anvil-shaped cloud -- the cumulonimbus.</p><p>This condenses even more air and generates more energy, with updrafts of more than 150 kilometres (90 miles) an hour.</p><p>It then rains, but the rain evaporates before it reaches the ground.</p><p>But it still cools the atmosphere where it falls, creating strong downdrafts.</p><div><br/></div><div><strong>- Are fire clouds rare? -</strong></div><div><br/></div><p>It is a common phenomenon in Portugal, California and Australia, where firefighters are more used to them. In Portugal, they had been rare until the deadly 2017 fires in Pedrogao Grande changed things.</p><p>In France, pyrocumulonimbus clouds are quite new. There were some in Landiras south of Bordeaux in 2022, but not for long.</p><p>Therefore, we need to learn how to manage fires that creates their own wind -- this is something relatively new.</p><div><br/></div><div><strong>- Is climate change to blame? -</strong></div><div><br/></div><p>Yes, it is. A consequence of global warming is more frequent heatwaves. While thunderstorms are common in the region of this fire, thunderstorm conditions after three successive heatwaves is a new combination.</p><div><br/></div><div><strong>- Are they predictable? -</strong></div><div><br/></div><p>Weather services can predict thunderstorms. But because these storms are located directly above a fire, we would need to know the fire&#x27;s exact location in advance. That&#x27;s impossible.</p><p>We can predict the conditions that will lead to these fires, but we won&#x27;t know exactly where they are.</p><p>The biggest challenge is how unpredictable they are. The fire in France&#x27;s southwest Gironde region started with northerly winds, then westerly, then southerly, then easterly, then back again to the south, then the west...</p><p>On top of that, there is this potential energy in the atmosphere which meant that, locally, the convection column sucked up the embers and carried the fire further afield.</p><p>The local conditions became catastrophic and the rate of the fire&#x27;s spread was staggering.</p><p>fbr/dl/rmb</p>

<p>Firefighters battling devastating fires in France have had to contend with a new threat: immense fire clouds that create their own wind and even lightning that can spark fresh blazes.</p>

Firefighters battling devastating fires in France have had to contend with a new threat: immense fire clouds that create their own wind and even lightning that can spark fresh blazes.