Tornadoes do more damages when travelling upward and tend to climb higher elevations rather than going downhill, according to a new study conducted by engineering researchers from the University of Arkansas.
They also discovered that when an area is surrounded by hills, tornadoes pass over the valleys below. The damage is only observed on the top of the hills.
The researchers, civil engineering professor Panneer Selvam and civil engineering graduate student Nawfal Ahmed, arrived at the conclusion after examining Google Earth images of the 2011 destructive tornadoes in Tuscaloosa, Ala., and Joplin, Mo.
They found resemblance between the two tornadoes in behavior and interaction with the terrain and claimed that the findings are applicable to all tornadoes.
The Tuscaloosa (April 27) and Joplin (May 22) tornadoes, that occurred within a month, are two of the most violent and costly natural disasters in recent U.S. history. The EF4 tornado in Tuscaloosa killed 64 people, while the EF5 Joplin twister killed 158 people.
"We wanted to understand the impact of terrain on damage magnitude and tornado path," said Selvam. "Information about this interaction is critical. It influences decisions about where and how to build, what kind of structure should work at a given site."
Selvam Ahmed placed tornado coordinates from the National Oceanic and Atmospheric Administration over Google Earth images and compared historical images to aerial photographs taken after the storms.
The data revealed greater damage as the tornadoes went uphill and massive damage on high grounds or ridges. When they arrive at a geographic intersection, tornadoes climb toward ridges rather than go downhill.
