Forest fire bloatingfire whirlwinds, powerful thunderstorms: when fires get big and hot enough, they can actually create their own weather.
In these extreme fire situationsConventional firefighting methods of directly controlling fires are not working, and forest fires are raging out of control.
But how can fire create weather?
I atmospheric scientist who uses the data collected by satellites in weather forecasting models to better predict extreme fire weather. Satellite data shows that fire-induced thunderstorms are far more common than anyone realized just a few years ago. Here's what's going on.
The Link Between Forest Fires and Weather
Picture a wild landscape of dry grass, brush, and trees. A spark falls, perhaps from lightning or a tree branch striking a power line. If the weather is hot, dry, and windy, that spark can quickly start a wildfire.
When vegetation burns, it releases a lot of heat. This heats the air near the ground, and this air rises like a balloon because hot air is less dense than cold air. Cooler air then rushes in to fill the void left by the rising air.
Here's how Forest fires create their own wind patterns.
What happens next depends on atmospheric stability. If the temperature drops rapidly with height above the ground, the rising air will always be warmer than the surrounding environment and will continue to rise. If it rises high enough, the moisture will condense, forming a cloud known as a pyrocumulus cloud or flammagenitus.
If the air continues to rise, at some point the condensed moisture will freeze.
When a cloud contains both liquid and frozen water particles, collisions between these particles may lead to separation of electric chargesIf the accumulated charge is large enough, an electrical discharge, better known as lightning, will occur, which will neutralize the charges.
Whether a cloud caused by a fire becomes a thunderstorm depends on three key ingredients: source of lift, instability and moisture.
Dry lightning
Wildfire sites typically have limited moisture. When conditions in the lower atmosphere are dry, this can lead to what is known as dry lightning.
No one living in a wildfire-prone environment wants to see dry lightning. This occurs when a thunderstorm produces lightning, but the precipitation evaporates before it reaches the ground. This means there is no rain to help put out the fires caused by lightning.
Fire whirlwinds
As air rises in the atmosphere, it can encounter different wind speeds and directions, a condition known as wind shear. This can cause the air to rotate. The rising air can tilt the rotation to a vertical position, tornado-like.
These fire whirls can have powerful winds that can spread flaming ash, starting new fires. However, they are not usually true tornadoes because they are not associated with rotating thunderstorms.
Fading Storms
Eventually, a wildfire-driven thunderstorm will begin to die out, and what went up will come back down. The downdraft from a dying thunderstorm can produce unstable winds on earthwhich further spreads the fire in an unpredictable direction.
When fires create their own weather, their behavior can become more unpredictable and erratic, which only increases the threat to residents and firefighters fighting the blaze. Predicting changes in fire behavior is important for everyone's safety.
Satellites show fires are not uncommon in the weather
Meteorologists admitted the ability of fires to cause thunderstorms in the late 1990s. But only after the launch GOES-R Series satellites in 2017 that scientists had high resolution images It is necessary to see that fire weather is in fact a common occurrence.
Today, these satellites can alert firefighters to new fires. even before the 911 callsThis is important because there is upward trend the number, size, and frequency of wildfires in the United States.
Climate change and the growing risk of fires
Heat waves and drought risk were grows in North Americawith rising global temperatures, which often leave dry landscapes and forests ripe for fire. And experiments with climate models show that Human-induced climate change will continue to increase this risk..
As more people move into fire-prone areas in a warming climate, risk of fires also grows. With the fires come cascading hazards that persist long after the fire has gone out, such as fire-damaged landscapes, are much more susceptible to landslides and mudflows that can impact water quality and ecosystems.
Communities can reduce their vulnerability to fire by constructing defensive spaces and firebreaks and make homes and property less vulnerableFirefighters can also reduce surrounding combustible loads through prescribed fire.
It is important to remember that fire is a natural part of the Earth system. As a scientist who studies fire Stephen J. Pine writes that we humans will have to reorient our relationship with fire in order to learn to live with fire.
This article is republished from Talka nonprofit, independent news organization providing you with facts and trusted analysis to help you make sense of our complex world. He wrote: Kyle Hilburn, Colorado State University
Read more:
Kyle Hilburn receives funding from the National Oceanic and Atmospheric Administration and the National Aeronautics and Space Administration.