How raging wildfires can create their own weather
We have been hearing a lot about wildfires for the last several weeks — first out west and now burning in parts of Atlantic Canada.
These out-of-control blazes rage through forests and can leave a charred path of destruction in their wake, but some fires become so intense they can create their own weather systems.
How is this possible? Think of what the weather is like on a warm or hot day. Warm air and water vapour rise from the surface and cool during the process. It cools to a point where the water vapour condenses to form those puffy fair-weather cumulus clouds, or sometimes cumulonimbus clouds associated with thunderstorms.
Similarly, a fire’s mass amount of intense heat cools and expands as it rises into the atmosphere. Once cooled, the water vapour condenses onto smoke and ash particles, forming smokey cumulus clouds above the fire.
These are known officially as flammagenitus clouds or pyrocumulus clouds.
Like cumulus clouds, pyrocumulus clouds can continue to develop vertically in our atmosphere and sometimes produce rainfall. They also can grow into pyrocumulonimbus clouds where lightning strikes and, in rare cases, tornadoes form.
While rainfall from these clouds can be beneficial, these wildfire clouds can make the situation more volatile, including rapid shifts in wind and visibility and lightning strikes that can ignite new fires.
Smoke from fires can also impact local air quality and travel thousands of kilometres away from the scene, creating hazy skies and more vibrant scenes at sunrise and sunset.
The situation unfolding in parts of our region is devastating and unfortunate, but at the same time, it’s unbelievable to see the various forces of nature at work.