Fujita scale

Fujita scale (fjē`tə, f`jētə) or F-Scale, standard scale for rating the severity of tornadoes as a measure of the damage they cause, devised in 1951 by the Japanese-American meteorologist Tetsuya (Ted) Fujita (1920–98). It classifies tornadoes on a hierarchy beginning with category F0, or "light" (winds of 40–72 mph; some damage to chimneys, TV antennas, roof shingles, trees, signs, and windows), which accounts for about 28% of all tornadoes. Category F1, or "moderate" (winds of 73–112 mph; automobiles overturned, carports destroyed, and trees uprooted), accounts for about 39% of all tornadoes. Category F2, or "significant" (winds of 113-157 mph; roofs blown off homes, sheds and outbuildings demolished, and mobile homes overturned), accounts for about 24% of all tornadoes. Category F3, or "severe" (winds of 158–206 mph; exterior walls and roofs blown off homes, metal buildings collapsed or severely damaged, and forests and farmland flattened), accounts for about 6% of all tornadoes. Category F4, or "devastating" (winds of 207–260 mph; few walls, if any, left standing in well-built homes and large steel and concrete missiles thrown great distances) accounts for about 2% of all tornadoes. Category F5, or "incredible" (winds of 261–318 mph; homes leveled or carried great distances and schools, motels, and other larger structures have considerable damage with exterior walls and roofs gone), accounts for less than 1% of all tornadoes. Category F6, or "inconceivable" (winds of 319–379 mph; automobiles become missiles), accounts for far less than 1% of all tornadoes.