The definition of the Fujita scale is a scale for measuring the wind speed of a tornado and its potential for destruction with F0 meaning wind speeds of 40-72 mph up to F6 which is wind speeds up to 319 to 380 mph.
An example of the Fujita scale is what a tornado expert would use to determine the damage a tornado could do if it sets down on a town.
a numerical scale for measuring the wind speed and corresponding destructive power of a tornado, ranging from F0 (40-72 mph) to F6 (319-380 mph)
Origin of Fujita scaleafter T. T. Fujita (1920-98), United States meteorologist who devised it
From the Japanese-American meteorologist Tetsuya Theodore "Ted" Fujita (藤田哲也).