FILE - This aerial photo taken April 28, 2011 shows tornado damage in Pleasant Grove, Ala. The photos and mementoes that were blown for hundreds of miles during the tornado outbreak two

 

              FILE - This aerial photo taken April 28, 2011 shows tornado damage in Pleasant Grove, Ala. The photos and mementoes that were blown for hundreds of miles during the tornado outbreak two
FILE - This aerial photo taken April 28, 2011 shows tornado damage in Pleasant Grove, Ala. The photos and mementoes that were blown for hundreds of miles during the tornado outbreak two years ago are giving researchers new insight on how debris is carried. University of Georgia associate professor John Knox says a new study has documented how one photo traveled nearly 220 miles through the atmosphere over Alabama and Tennessee. (AP Photo/Dave Martin, File)