New research by scientists at the University of Iowa suggests that smoke from fires actually increases the likelihood and intensity of tornadoes.
Researchers came to this conclusion after studying one severe weather event that occurred on April 27, 2011. That day brought over 100 tornadoes that resulted in over 300 deaths in the southeast U.S.
Although the weather that day was already affected by those conditions that make tornadoes likely, smoke from fires in Central America that drifted into the area made the tornadoes more intense, and therefore, more dangerous.
Every spring, farmers all over the world clear their land by burning it. That causes smoke particles to rise into the air during a time when tornadoes are already likely in certain states. In models, researchers showed that with the 2011 event, those Central American smoke particles drifted across the Gulf of Mexico and joined up with a large weather cell, causing its wind shear to increase and its cloud base to fall, creating intense tornadic activity.
In their simulations, researchers studied tornadic activity with smoke and without. As expected, they found that smoke increased wind shear and lowered the cloud base of the 2011 storm. Their results suggest that this storm was possibly more severe because of the smoke.
This is the first published study done that looks at the link between tornadoes and smoke from fires.
"These results are of great importance, as it is the first study to show smoke influence on tornado severity in a real case scenario," says Gregory Carmichael, professor of chemical and biochemical engineering at the University of Iowa. "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."
These researchers plan on continuing their study, though to see if smoke played a part in any other particularly bad tornado events. They also hope to work with weather forecasters in including the presence of smoke for future weather prediction models.
Over the past three years, the U.S. has seen an average of 909 tornadoes per year, with 16 per year creating massive damage and resulting in fatalities. Although forecasting methods have slightly improved in previous years, understanding what makes tornado events more severe could improve weather forecasting and potentially save lives.
Although global warming plays a part in the increase in severe tornadoes in recent years, it is still important to understand other factors that make tornadic activity likely in certain areas.