Last week, Ontarians gawked at apocalyptic skies as forest fire smoke descended upon much of the province, blocking out the sun and corrupting air quality as far as New York City.
These smoggy conditions are the result of what the province’s latest numbers are saying is already the worst forest fire season on record, beating out 2021 as 7,250 square kilometres of Ontario’s forests burn to the ground. The massive amounts of smoke are spoiling outdoor fun and increasing health risks across the province, but they’re also having a surprising impact on weather patterns.
Within five to 10 kilometres of a forest fire, there’s an immense heat, but away from the flames and under a blanket of smoke, a cooling effect is often seen. This is because the smoke particles scatter and absorb the sun’s rays, making it harder for heat to reach the earth’s surface, says Brian Wiens, the managing director at Canada Wildfire NSERC Strategic Network.
“Smoke acts like a cloud, scattering sunlight back,” says Wiens. “We’ve seen that temperatures will get forecasted, for example, and then it gets smoky and all of a sudden it’s several degrees cooler outside than what was originally forecasted.”
Do these cloud sayings really predict the weather?
Since rising hot air is required for thunder- and rain-cloud formation, cold ground conditions can also mean less storms and precipitation. On top of cool conditions, Wiens points to a growing body of research that indicates smoke particles disrupt the precipitation process itself. “An abundance of carbon particles within clouds can make it harder for the raindrops to coalesce and become large enough to fall to earth,” he says.
The result is drier conditions that only increase the potential for more forest fires. On top of that, Wiens says emerging research suggests that when thunderstorms do form, the smoke particles can alter the physics of a thundercloud and make them more dangerous.
This is why we get such stormy weather in the summer
“In a smoky situation, the way thunderstorms form seems to change, and you get more positive strokes—when electrons are drawn from the ground into the cloud, instead of from the cloud to the ground,” he says. “These strokes are stronger than negative ones and tend to be a higher risk for starting more fires.”
As global temperatures continue to rise, Wiens says forest fires will become more prevalent, and drier conditions, paired with more fire-prone thunderstorms, may only make matters worse. So while a string of cooler days under dense smoke may seem like a relief, “the overall impact of climate change is stronger,” says Wiens. “The climate becoming hotter, drier, and windier is going to create more fires than a day or two of cooling can offset.”
Related Story Here’s what cottagers should know before the next thunderstorm rolls in
Related Story What could the Super El Niño mean for Canadian cottagers?
Related Story Cottage Q&A: Why does mild winter weather cause cloudy skies?