Wildfires can create their own weather, spreading the flames further – an atmospheric scientist explains how

Fires ExplosionsFire whirlwinds, gigantic storms: When fires get big and hot enough, they can create their own weather.

In these extreme fire situations, firefighters’ common methods of directly controlling the fire do not work and wildfires grow out of control. Firefighters observed many of these risks in Huge Fire Park burning near Chico, California, in the summer of 2024.

But how can a fire create weather?

I am one atmospheric scientist which uses data collected by satellites in weather forecast models to better anticipate extreme fire weather phenomena. Satellite data shows that fire-triggered storms are much more common than imagined just a few years ago. Here’s what’s happening.

Wildfire and climate connections

Imagine a wild landscape with dry grass, bushes and trees. A spark strikes, perhaps from lightning or a tree branch striking a power line. If the weather is hot, dry and windy, that spark can quickly ignite a wildfire.

When vegetation burns, large amounts of heat are released. This heats the air near the ground and this air rises like a hot air balloon because warm air is less dense than cold air. Cooler air then moves in to fill the void left by the rising air.

And so wildfires create their own wind patterns.

What happens next depends on the stability of the atmosphere. If the temperature cools rapidly with elevation above the ground, then the rising air will always be warmer than the surrounding air and will continue to rise. If it rises high enough, the moisture will condense, forming a cloud known as a pyrocumulus or flamegenite.

If the air continues to rise, at some point the condensed moisture will freeze.

Since a cloud contains liquid and frozen water particles, collisions between these particles can lead to electrical charge separation. If the charge accumulation is large enough, an electrical discharge – better known as lightning – will occur to neutralize the charges.

Whether a fire-induced cloud will become a storm depends on three main ingredients: a source of support, instability, and moisture.

dry lightning

Wildfire environments typically have limited humidity. When conditions in the lower atmosphere are dry, this can lead to what is known as dry lightning.

No one who lives in a wildfire-prone environment wants to see dry lightning. It occurs when a thunderstorm produces lightning, but the precipitation evaporates before reaching the ground. This means there is no rain to help put out lightning-caused fires.

Fire whirlpools

As air rises into the atmosphere, it may encounter different wind speeds and directions, a condition known as wind shear. This can cause the air to swirl. Rising air can tilt the spin vertical, looking like a tornado.

These fire whirls can have strong winds that can spread flaming ash, sparking new areas of fire. They are usually not true tornadoes, because they are not associated with rotating thunderstorms.

Decaying storms

Eventually, the storm triggered by the fire will begin to die down and what went up will come down again. The downdraft from the decaying storm can produce erratic winds on the groundfurther spreading the fire in directions that may be difficult to predict.

When fires create their own climate, their behavior can become more unpredictable and erratic, which only amplifies the threat to residents and firefighters battling the blaze. Anticipating changes in behavior in the event of a fire is important for everyone’s safety.

Satellites show that fire-created weather is not so rare

Meteorologists recognized the ability of fires to create storms at the end of the 1990s. But it was only with the launch of GOES-R Series satellites in 2017 that scientists had to high resolution images It is necessary to see that fire-induced weather is indeed common.

Today, these satellites can alert firefighters to a new fire even before 911 calls. This is important because there is a growing trend on the number, size, and frequency of wildfires in the United States.

Climate change and increasing fire risks

Heat waves and the risk of drought have been increasing in North America as global temperatures rise, more often leaving landscapes dry and forests primed to burn. And experiments with climate models indicate that human-caused climate change will continue to increase this risk.

As more people move to fire-risk areas in this increasingly hot climate, it is not surprising that the risk of starting fires and the spread is increasing. With fireworks come cascading dangers that persist long after the fire has been put out, like burn-scarred landscapes that are much more susceptible to landslides and debris flows that can affect water quality and ecosystems.

It is important to remember that fire is a natural part of the Earth system. Communities can reduce their vulnerability to fire damage building defensible spaces and firebreaks and making homes and properties less vulnerable. Firefighters can also reduce surrounding fuel loads with prescribed fire.

As a fire scientist Stephen J. Pyne writes, we, as humans, will have to reorient our relationship with fire so that we can learn to live with fire.

This article was republished from The conversation, an independent, nonprofit news organization that brings you trusted facts and analysis to help you understand our complex world. It was written by: Kyle Hilburn, Colorado State University

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Kyle Hilburn receives funding from the National Oceanic and Atmospheric Administration and the National Aeronautics and Space Administration.