科学美国人60秒:Smoke Makes Twisters More Likely to Strike

What could fires in Central America have to do with the deadliest outbreak of tornadoes in recent U.S. history? More than you might think, according to a new study. Researchers found that smoke wafting north from the Gulf of Mexico worsened the already-stormy weather brewing across the southeastern US on April 27, 2011. That afternoon, 122 twisters tore across the country, killing 313 people.

"It’s not that the outbreak happened because of the smoke." Pablo Saide, of the University of Iowa, and an author of a new study published in the journal Geophysical Research Letters. [Pablo Saide et al, Central American biomass burning smoke can increase tornado severity in the U.S.] "What’s happening is that this smoke, it interacts with clouds and with solar radiation."

Smoke consists of tiny particles, called aerosols, which can have complicated effects on weather. So Saide used a model to explore whether these particles influenced the tornado outbreak of April 27. He found smoke made twisters more likely to strike, and more ferocious when they did. However, at the moment, weather forecasts don’t consider aerosol particles. 

"This is difficult because weather models need to be finished very fast—because you want weather predictions for today, not for tomorrow. And including these aerosols makes it slower."

But Saide thinks it’s worth it. He says understanding the role of smoke and other airborne particles will help forecasters predict when weather conditions might change from dreary to deadly.

—Julia Rosen 

[The above text is a transcript of this podcast.]