Iowa Now | Can smoke from fires intensify tornadoes?
“Yes,” say University of Iowa researchers, who examined the effects of smoke—resulting from spring agricultural land-clearing fires in Central America—transported across the Gulf of Mexico and encountering tornado conditions already in process in the United States.
The UI study, published in the journal Geophysical Research Letters, examined the smoke impacts on a historic severe weather outbreak that occurred during the afternoon and evening of April 27, 2011. The weather event produced 122 tornadoes, resulted in 313 deaths across the southeastern United States, and is considered the most severe event of its kind since 1950.
The outbreak was caused mainly by environmental conditions leading to a large potential for tornado formation and conducive to supercells, a type of thunderstorm. However, smoke particles intensified these conditions, according to co-lead authors Gregory Carmichael, professor of chemical and biochemical engineering, and Pablo Saide, Center for Global and Regional Environmental Research (CGRER) postdoctoral fellow.
They say the smoke lowered the base of the clouds and increased wind shear, defined as wind speed variations with respect to altitude. Together, those two conditions increased the likelihood of more severe tornadoes. The effects of smoke on these conditions had not been previously described, and the study found a novel mechanism to explain these interactions.
