Where does the F come from in an F5 tornado ?

The tornado is “a violently rotating column of air, pendant from the cumuliform cloud as well as underneath a cumuliform cloud, and often (although not always) visible like a funnel cloud. ” Literally, in order for any vortex to be classified as being a tornado, it must be in contact with the ground as well as the cloud base. Weather scientists didn’t find it so simple in practice, however, to classify and also to define tornadoes. For example, the difference is actually unclear between a strong mesocyclone (parent thunderstorm circulation) on the earth, and a big, weak tornado. Wind speeds in tornadoes vary from values below that of hurricane speeds to greater than 300 miles hourly! Differing from hurricanes that will produce wind rates of speed of similar values over relatively widespread areas, the maximum winds in tornadoes in many cases are confined to very small areas, and vary greatly over very small distances, even within your funnel itself. The tales of complete destruction of just one house in the center of many that will be totally undamaged tend to be true and very well documented.

In 1971, Dr. T. Theodore Fujita from the University of Chicago, il devised a six-category scale to classify U. S. tornadoes into 6 intensity categories, named F0-F5. These categories are based on the estimated highest winds occurring inside the funnel. The Fujita Tornado Scale, more commonly known as the “F Scale”, has subsequently ended up being the accepted and acknowledged scale for calculating wind speeds within tornadoes based on the damage performed to buildings as well as other structures. It is used extensively by the National Weather Service in investigating tornadoes, and by technicians in correlating destruction of building structures as well as techniques with various wind speeds brought on by tornadoes. All tornadoes are actually assigned an F scale when described by meteorologists.

The F Scale bridges the gap between the Beaufort Wind Velocity Scale and Mach figures (ratio of the speed of an object to the speed of sound) by linking Beaufort Force 12 together with Mach 1 inside twelve steps. The equation relating the wind velocities (V in mph) while using the F scale (F) is V = 14. 1 * ((F+2) to the 1. 5 power).

F1 on the actual F Scale is corresponding to B12 (73 mph) in the Beaufort scale, which is the actual minimum windspeed necessary to upgrade a tropical storm into a hurricane. F12 on the actual F Scale is corresponding to M1 (738 mph) in Mach numbers. Though the F Scale itself ranges up to F12, the strongest tornadoes max out within the F5 range (261 to 318 mph).

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