Fujita scale(redirected from Twisdale Scale)
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Fujita scale(fo͞ojē`tə, fo͞o`jētə) or
F-Scale,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). Since 2007 the National Weather Service has used the Enhanced Fujita scale or EF-Scale, developed by the Texas Tech Univ. Wind Science and Engineering Research Center in conjunction with other wind engineers and meteorologists. Incorporating improved knowledge of wind speeds and the resulting damage, as well as including more damage indicators (and thus allowing for a more accurate assessment of a tornado based on the destruction it caused), the EF-scale retains the categories used by the Fujita scale but has revised the associated wind speeds.
The revised scale classifies tornadoes on a hierarchy beginning with category EF0, or "light" (winds of 65–85 mph; some damage to chimneys, TV antennas, roof shingles, trees, signs, and windows), which accounts for about 28% of all tornadoes. Category EF1, or "moderate" (winds of 86–110 mph; automobiles overturned, carports destroyed, and trees uprooted), accounts for about 39% of all tornadoes. Category EF2, or "significant" (winds of 111–135 mph; roofs blown off homes, sheds and outbuildings demolished, and mobile homes overturned), accounts for about 24% of all tornadoes. Category EF3, or "severe" (winds of 136–165 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 EF4, or "devastating" (winds of 166–200 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 EF5, or "incredible" (winds of over 200 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. Under the original Fujita scale, Category F0 had estimated winds of 40–72 mph; F1, 73–112 mph; F2, 113–157 mph; F3, 158–206 mph; F4, 207–260 mph; and F5, 261–318 mph.