Fujita Tornado Scale

The Fujita Tornado Intensity Scale is a standard six-point scale used for rating the intensity of a tornado or other severe wind inferring its wind force from the type and extent of the damage it caused after it has passed over a man-made structure. It also measures both the path lenght and the path width.

The maximum wind speed is estimated and thus not comparable with direct measurements by Doppler radar. Class F5 tornadoes are rare. The scale was introduced in 1971 by Tetsuya Theodore Fujita and Allen Pearson and is also known as the Fujita-Pearson Scale.

The Fujita Scale may not be a perfect system for linking damage to wind speed, but it was simple to use in daily practice and it is widely accepted today.

However, one key point to remember is that the size of a tornado is not necessarily an indication of its intensity. Large tornadoes can be weak, small tornadoes van be violent. The Fujita scale is based on damage, not the appearance of the funnel. The Fujita scale is very subjective, and varies according to how experienced the surveyor is. The official rating is usually set by the national weather services.

Media hype and inexperience with tornado damage plays a big part in exaggerated F-Scale claims seen on television or in the papers.

The Fujita Tornado Damage Scale
F-SCALE	WIND SPEED		DAMAGE DESCRIPTION
	mph	kph
F0	<72	<116	light - some damage to chimneys; branches broken off trees, shallow-rooted trees uprooted, sign boards damaged	There is another innofficial Fujita force. F6 - inconceivable damage with estimated winds greater than 320 mph. These winds are very unlikely. The small area of damage they might produce would probably not be recognizable along with the havoc produced by F4 and F5 wind that would surround the F6 winds. Missiles, such as cars and refrigerators would do serious secondary damage that could not be directly identified as F6 damage. If this level is ever achieved, evidence for it might only be found in some manner of ground swirl pattern, for it may never be identifiable through engineering studies 广告 气象辞典 A is for Air Accessory clouds Advection Air masses and their sources Air-mass Thunderstorm Alpine Glow Altocumulus Anticyclone Atmosphere - Diagram Aurorae - Northern Lights Average rainfall over England and Wales Azores High Banner Cloud - the peak's flag Beaufort Scale Blizzard British Weather Terms Brocken Spectre Bubble High Burning Time CAPE - Convective Available Potential Energy Cap cloud Cc floccus Cc lacunosus Cc stratiformis Cc undulatus Central England Temperature Centres of action Ci fibratus Ci radiatus Ci spissatus Ci uncinus Ci vertebratus Cirrocumulus Cirrostratus Cirrus Clocks go Back from BST to GMT Cloud classification Cloud seeding Cloud species Cloud streets Cloud types (genera) Cloud variety Clouds - sentry of the sky Cold low Comma Cloud Convection Coriolis effect Corona Crepuscular rays Cut-off low Dew Dew Point Discovery of the Jet Stream Doppler radar Drifting snow - blowing snow Drought Earth's Atmosphere El Nino Föhn (foehn) wind Föhn wall Flash Flood Fog and Mist Fogbow Forecasting weather Frost hollow Fujita Scale Statistics Fujita Tornado Scale Funnel cloud Genoa Low Geostationary Satellites Geostrophic Wind Glaze and Black Ice Glory Grass Minimum Temperature Gulf Stream (Satellite) Gustnado Hailstorms in Britain Hail Highs and Lows and Winds History of Hurricane Names Hoar Frost Humidity Inversions Isobars on surface maps Jack Frost Jet stream cirrus from space Katabatic winds Key to our weather symbols Lake-effect snow Latent Heat Levanter cloud Lightning strike Millibar and hectopascal Mirages Mizzle NOAA satellites Nimbostratus North Atlantic Drift (Gulf Stream) Polar Orbiting Satellites Polar low - the arctic hurricane Precipitation Map Radiosonde Rain gauge Rime Roll cloud Rotor cloud Saffir-Simpson scales Sc duplicatus Sc perlucidus Sc undulatus Shelf Cloud Sometimes a bit fishy Sounding Southern Oscillation St. Swithun's Day Standard Reference Period Stevenson Screen Stratocumulus Stratosphere Sun pillar Supercooled clouds Surface wind Swell TORRO Thermocline Thunderstorm Probability Thunderstorms Tornado Alley Troposphere Troposphere - Diagram UV Index Ultraviolet radiation Virga or Fallstreak What Makes Northern Lights Happen? What does it mean? Where Lightning Strikes Why Skies are Blue Why Thunder Rumbles World Meteorological Organisation (WMO)