Wild Weather


Tornadoes - II

Enhanced Fujita Tornado Damage Scale

All tornadoes, and most other severe local windstorms, are assigned a single number from the Enhanced Fujita Scale according to the most intense damage caused by the storm. Here is a breakdown of the EF Scale:

Scale Rating Wind Speed Potential Damage
EF0 Weak 65 - 85 mph Light damage
Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged.
EF1 Weak 86-110 mph Moderate damage
The lower limit is the beginning of hurricane wind speed; peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads; attached garages may be destroyed.
EF2 Strong 111-135 mph Significant damage
Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; highrise windows broken and blown in; light-object missiles generated.
EF3 Strong 136-165 mph Severe damage
Roofs and some walls torn off well-constructed houses; most trees in forest uprooted; skyscrapers twisted and deformed with massive destruction of exteriors; heavy cars lifted off the ground and thrown.
EF4 Violent 166-199 mph Devastating damage
Well-constructed houses leveled; structures with weak foundations blown away some distance; trains overturned; cars thrown and large missiles generated. Skyscrapers and highrises toppled and destroyed.
EF5 Violent > 200 mph Incredible damage (rare)
Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile sized missiles fly through the air in excess of 100 m (109 yd); trees debarked; steel reinforced concrete structures badly damaged.

Determine the Strength of a Tornado

Here is an hands-on activity for you to explore how the width of a tornado and the pressure difference between the surrounding air and the center of the funnel relate to the destructive wind damage a twister can produce.

Step 1) Using the slider controls below to adjust the funnel width and core pressure difference in the simulation
Step 2) Click "Go". The simulation will show the effect and damage of the tornado you just built.
Step 3) Observe carefully the types of damage and determine its strength according to the Fujita Scale above.

Funnel width +        Funnel speed + Go