Fires Intensified Deadly Tornado Outbreak
Fires Intensified Deadly Tornado Outbreak
by Becky Oskin, Senior Writer | February 03, 2015 02:02pm ET
One of the deadliest tornado outbreaks in U.S. history was strengthened by smoke from burning farmlands in Central America, a new study suggests.
On April 27, 2011, some 200 terrifying twisters touched down across the Southeast — the most on record in a single day. Damages topped $11 billion, and 316 people died. (The devastation on April 27 was the worst of a four-day tornado outbreak spanning April 25 through April 28.)
The hardest hit states were Mississippi, Alabama, Tennessee and Georgia, which were struck by 15 tornadoes ranked EF-4 or higher on the Enhanced Fujita Scale. There were also four powerful EF-5 tornadoes — the highest possible tornado ranking — as severe storms raked through these states. (Destructive U.S. Tornadoes of April 2014: Gallery)
Researchers now say that air pollution intensified this incredible tornado outbreak. When supercell storms on April 27, 2011, mixed with smoke in the air, the volatile combination boosted the conditions that trigger tornados, according to a study published Jan. 26 in the journal Geophysical Research Letters.
However, the study notes that the twisters were primarily caused by the storms, not by smoke. "The smoke is not responsible for this outbreak," said Pablo Saide, lead study author and a postdoctoral researcher at the University of Iowa's Center for Global and Regional Environmental Research. "The main driver is the environmental conditions — the temperature and the wind profiles."
During the tornado outbreak, a satellite recorded high levels of smoke drifting across the Gulf of Mexico from burning fields in eastern Mexico and the Yucatan Peninsula. (Pollution from agricultural burning is also a concern in the United States, where several states have regulated the practice under the Clean Air Act of 1990.)
The pollution included soot and aerosols, which are fine particles and droplets suspended in the air. In the new study, the researchers looked at what effects these pollutants may have had on the birth of tornadoes, using a climate model. The researchers found two main effects, which required aerosols to be both close to the Earth's surface and above the cloud layer, Saide said.
More:
http://www.livescience.com/49681-severe-tornadoes-air-pollution-linked.html
Science:
http://www.democraticunderground.com/122835552