According to a new research the frequency of the large tornado outbreak is increasing in the United States. Researchers found that the cause is not about the global warming as previous models suggest.
The study by researachers and Joel E. Cohen, whom is a visiting scholar at the University of Chicago, finds that occurring increase of large outbreaks does not involve global warming.
Instead, their research shows that the growth in frequency to trends in the vertical wind shear found in certain supercells. This is a change not related to a warmer climate.
Cohen said that whatever is pushing this rise in extreme tornado outbreaks, during which the vast majority of tornado-related fatalities occur, is far from obvious in the present state of climate science.
Tornado outbreaks or large-scale weather events that last one to three days. Featuring several thunderstorms and six or more tornadoes in close cycle.
The study that was published in December 16 issue of Science, the researchers used National Oceanic and Atmospheric Administration datasets and other new statistic tools.
This new statistical tool involves extreme value analysis. This is a branch of statistics dealing with deviations. It analyzes observation-based meteorological estimates associated with tornado outbreaks.
The researchers found that over the century the number of tornado outbreaks doubled. This means that in 1965 the worst outbreak expected over five years would have had about 40 tornadoes.
While in 2015 the worst outbreak expected over five years would have had about 80 tornadoes.
According to the Science Daily, Cohen said upon viewing the data of thousands of tornado outbreaks over the last century in the United States.
To be able to understand the increased frequency in tornado outbreaks, the researchers looked at two factors: convective available potential energy, or CAPE which is a measure of the amount of energy available for convection, and storm relative helicity, which is a measure of vertical wind shear.
According to UChicago News, the study rises another question what climate change could to sever thunderstorms and what is responsible for recent trends.
The study also says that in the near future we are expected to have more large scaled tornado outbreaks.
