Most people know lightning can spark wildfires. But wildfires can also spark lightning—a phenomenon that has puzzled scientists for decades. Now, re

Air pollution helps wildfires create their own lightning

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2021-06-14 16:30:08

Most people know lightning can spark wildfires. But wildfires can also spark lightning—a phenomenon that has puzzled scientists for decades. Now, researchers have revealed a key cause of this phenomenon: air pollution. Dirtier air means more lightning above wildfires—and more rain, too.

The finding “demonstrates that we should be thinking about the impact air pollution has on weather systems, including the impact on storms,” says Joel Thornton, an atmospheric scientist at the University of Washington, Seattle, who was not involved in the research.

Many factors are believed to cause lightning during a wildfire. Scientists have blamed everything from air currents to urbanization. These elements have been hard to disentangle in the air above land because the rough topography, changing land use, and varying heat create a complex set of variables that are hard to tease out.

Enter Australia’s devastating 2019–20 fire season. Known as “Black Summer,” massive blazes charred more than 186,000 square kilometers of land, and large amounts of smoke billowed southeast over the Tasman Sea. But the vast, flat, cool surface of the sea provided an opportunity to study the fires over a relatively blank canvas.