Tornadoes are nature’s most violent storms.  They damage or destroy everything in their path, including weather equipment.  Therefore, in order to gauge the strength of a tornado, experts use the Enhanced Fujita Scale.  It infers wind speeds from the damage left in the wake of a storm.

Dr. Ted Fujita, a severe weather research scientist at the University of Chicago, developed the original Fujita scale in 1971. The National Weather Service used it from 1973 until 2007, when they adopted the Enhanced Fujita scale. A commission of meteorologists and structural engineers formulated the new model.  It maintains the original scale’s six categories, but refines their wind speeds to reflect differences in construction quality and improved damage survey techniques.

The different categories, EF-0 through EF-5 represent increasing wind speeds and escalating degrees of damage.

Chart Data: NOAA