Land-Clearing Smoke Linked to Stronger Tornadoes?

Smoke caused by land clearing may be linked to stronger, more intense tornadoes, according to a new study.

Researchers from the University of Iowa (UI) focused on a historic extreme weather event that occurred in April 2011, which produced 122 tornadoes and resulted in 313 deaths across the southeastern United States. This weather outbreak - considered the most severe event of its kind since 1950 - was caused mainly by environmental conditions leading to a large potential for tornado formation and conducive to supercells (a type of thunderstorm).

However, this team of researchers believes that smoke - resulting from spring agricultural land-clearing fires in Central America - swept across the Gulf of Mexico and intensified these tornado conditions.

"These results are of great importance, as it is the first study to show smoke influence on tornado severity in a real case scenario. Also, severe weather prediction centers do not include atmospheric particles and their effects in their models, and we show that they should at least consider it," co-lead author Gregory Carmichael said in a statement.

Researchers say the smoke lowered the base of the clouds and increased wind shear - wind speed variations with respect to altitude. Previous research has not focused on smoke's effects on tornadoes before, so for this study the UI team relied on novel computer simulations based upon data recorded during the 2011 event. One type of simulation included smoke and its effect on solar radiation and clouds, while the other omitted smoke.

The researchers hope their findings, published in the journal Geophysical Research Letters, will lead to more accurate forecasts that include "the implementation, testing and incorporation of these effects on operational weather prediction models," added co-lead author Pablo Saide.

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