As France and Spain battle some of the worst wildfires in recent history, experts are warning about a rare phenomenon that could make the fires even worse: pyrocumulonimbus, or “fire clouds.”
Wildfires usually spread when it’s hot, windy, and dry. But severe wildfires can actually create their own weather. One of the most dramatic examples is pyrocumulonimbus clouds—basically, thunderstorms caused by the fire itself. These are the most extreme type of fire clouds.
Here’s what you need to know about them.
What is a “fire cloud”?
Simply put, pyrocumulonimbus (or “pyroCb”) clouds are huge storm clouds created by a wildfire.
Massive wildfires release a lot of energy and heat, which rises quickly in a column of smoke. When that smoke plume rises high enough, the low pressure in the atmosphere cools the air, and moisture condenses to form a cloud. These clouds can produce lightning and strong winds.
If a wildfire is big and intense enough, the smoke plume can turn into a pyrocumulonimbus cloud. These clouds can reach heights of 10 to 15 kilometers (6 to 9 miles) and even push into the stratosphere. NASA calls them “the fire-breathing dragon of clouds.”
“It’s a full thunderstorm forming inside the fire plume,” says Rick McRae, an adjunct professor with the bushfire research group at the University of New South Wales (UNSW). “These things can take up about 10,000 cubic kilometers of the atmosphere, so they have a big impact.”
Why are these fire clouds so dangerous?
When pyrocumulonimbus clouds form, they can create winds that make the wildfires below spread even faster. They can also generate their own lightning, which can start new fires far away.
Experts say stronger wind gusts can make fire behavior more unpredictable, making conditions more dangerous for firefighters on the ground.
“The cloud is a sign that the fire is very dangerous,” says McRae, who worked as a senior fire manager for 30 years. “It confirms that it was right to evacuate a lot of people.”
How common are fire clouds?
Australia started seeing pyrocumulonimbus clouds at the beginning of this century, and experts say they seem to be happening more often.
They also formed during massive wildfires in California in 2022. But this could be new for France.
If confirmed, it would be the first time a pyroCb has been observed in France.
“It’s the first time France has had to seriously think about the idea of a pyroCb,” says McRae. “Whether or not they had one a few days ago isn’t really the question,” he adds. “The question is whether one is coming on Tuesday or Wednesday this week.”
Why are these clouds happening more often?
The climate crisis is creating more dangerous conditions for wildfires around the world, and also the conditions that lead to pyrocumulonimbus clouds.
“It’s not as simple as just turning up the temperature,” says McRae. “It’s full-on climate change. It’s changes in the atmosphere, changes in surface weather, changes in a lot of things.”
Experts say climate models suggest these trends will get worse in the future.
The wildfires in Europe are happening during peak tourist season in a region that has been hit by repeated heatwaves. Woodland areas have dried out due to a lack of rain since May.
Weather forecasters warn that another heatwave could hit France starting Tuesday, with temperatures reaching 40°C in some areas.
“There’s going to be a blob of intense heat moving from Czechia over four or five days,” says McRae.
Frequently Asked Questions
Here is a list of FAQs about fire clouds written in a natural tone with clear direct answers
BeginnerLevel Questions
1 What exactly is a fire cloud
Its a cloud that forms directly above a large intense wildfire The heat from the fire forces smoke ash and moisture high up into the atmosphere where it condenses into a cloud
2 Is a fire cloud dangerous
Yes very It can create its own weather including lightning strong winds and even fire tornadoes The lightning can start new fires far away from the main blaze
3 Whats the difference between a fire cloud and a regular cloud
A regular cloud forms from normal weather patterns A fire cloud is created by the heat of a wildfire and is filled with smoke and ash instead of just water droplets
4 Can a fire cloud produce rain
Sometimes If the cloud grows tall and cold enough it can produce rain However this rain is often dark and dirty and may evaporate before reaching the ground creating a dry thunderstorm
5 Why is it called a fire cloud
Because it is literally born from the fire The scientific name is a pyrocumulonimbus cloud
Advanced Technical Questions
6 How tall can a fire cloud get
They can grow incredibly tall reaching up to 50000 feet or moresometimes pushing into the stratosphere Thats as tall as a supercell thunderstorm
7 Can a fire cloud cause a fire tornado
Yes The intense updraft from a fire cloud can create a rotating column of air When this mixes with the fire it can form a fire whirl or even a true fire tornado
8 How does a fire cloud create its own lightning
The violent updraft inside the cloud causes ice particles and ash to collide building up an electrical charge This charge releases as lightning which can strike miles away from the main fire
9 Whats the difference between a pyrocumulus and a pyrocumulonimbus
