Natural gas is mostly methane. In my piece on the Cornell study, my subhed was âLeakage of methane from fracking boosts shale gas global warming impact.â I didnât note until several paragraphs later that âNatural gas is composed largely of methane,â which comes from the second sentence of the study itself.
Tornado strength is currently measured on what is called the Enhanced Fujita Scale (adapted from the simpler Fujita Scale in 2007), which gives the tornado a rating from 0 to 5 based on estimated wind speeds and the severity of the damage.
F5: Incredible tornado (261-318 mph). Incredible damage. About 70 percent of tornadoes are weak and last between one and 10 minutes. About 10 percent of tornadoes are strong and last 20 minutes or more. Only two percent of tornadoes are considered violent. Violent tornadoes cause the most deaths and can last for well over an hour.