The scale for measuring tornado intensity, developed by T. Theodore Fujita of the University of Chicago, examines the damage caused by the tornado after it has passed over a man-made structure. Though the scale has been updated, here are general ranges for each level:
F0 Wind speed of less than 73 mph: Light damage. Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged.
F1 Wind speed of 73-112 mph: Moderate damage. Roof surfaces peeled off; mobile homes pushed off foundations or overturned; moving autos blown off roads.
F2 Wind speed of 113-157 mph: Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground.
F3 Wind speed of 158-206 mph: Severe damage. Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown.
F4 Wind speed of 207-260 mph: Devastating damage. Well-constructed houses leveled; structures with weak foundations blown away some distance; cars thrown and large missiles generated.
F5 Wind speed of 261-318 mph: Incredible damage. Strong frame houses leveled off foundations and swept away; automobile-size missiles fly through the air in excess of 100 meters (109 yards); trees debarked; incredible phenomena will occur.
Source: NOAA
