A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which, from an observer looking down toward the surface of the Earth, winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern. Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than 180 kilometers per hour, are about 80 meters across, and travel several kilometers before dissipating. The most extreme tornadoes can attain wind speeds of more than 480 kilometers per hour (300 mph), are more than 3 kilometers (2 mi) in diameter, and stay on the ground for more than 100 km (62 mi).
The Fujita scale, or Fujita–Pearson scale, is a scale for rating tornado intensity, based primarily on the damage tornadoes inflict on human-built structures and vegetation. The official Fujita scale category is determined by meteorologists and engineers after a ground or aerial damage survey, or both; and depending on the circumstances, ground-swirl patterns, weather radar data, witness testimonies, media reports and damage imagery, as well as photogrammetry or videogrammetry if motion picture recording is available. The Fujita scale was replaced with the Enhanced Fujita scale (EF-Scale) in the United States in February 2007. In April 2013, Canada adopted the EF-Scale over the Fujita scale along with 31 "Specific Damage Indicators" used by Environment Canada (EC) in their ratings.
The 2005 Birmingham tornado was one of the strongest tornadoes recorded in Great Britain in nearly 30 years, occurring on 28 July 2005 in the suburbs of Birmingham. It formed on a day when thunderstorms were expected to develop across the Midlands and eastern England. The tornado struck at approximately 14:30 BST in the Sparkbrook area and also affected King's Heath, Moseley and Balsall Heath as it carved a 7 kilometre-long path through the city.
The TORRO tornado intensity scale is a scale measuring tornado intensity between T0 and T11. It was proposed by Terence Meaden of the Tornado and Storm Research Organisation (TORRO), a meteorological organisation in the United Kingdom, as an extension of the Beaufort scale.
The Enhanced Fujita scale rates tornado intensity based on the severity of the damage they cause. It is used in some countries, including the United States, Canada, France, China, and Mongolia.
The Tornado and Storm Research Organisation (TORRO) was founded by Terence Meaden in 1974. Originally called the Tornado Research Organisation, it was expanded in 1982 following the inclusion of the Thunderstorm Census Organisation (TCO) after the death of its founder Morris Bower and his wife. The current Head of TORRO is Paul Knightley, a professional meteorologist.
Tornado intensity is the measure of wind speeds and potential risk produced by a tornado. Intensity can be measured by in situ or remote sensing measurements, but since these are impractical for wide-scale use, intensity is usually inferred by proxies, such as damage. The Fujita scale, Enhanced Fujita scale, and the International Fujita scale rate tornadoes by the damage caused. In contrast to other major storms such as hurricanes and typhoons, such classifications are only assigned retroactively. Wind speed alone is not enough to determine the intensity of a tornado. An EF0 tornado may damage trees and peel some shingles off roofs, while an EF5 tornado can rip well-anchored homes off their foundations, leaving them bare; even deforming large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler radar data, photogrammetry, and ground swirl patterns may also be analyzed to determine the intensity and assign a rating.
The 2006 London tornado was a significant United Kingdom tornado spawned from a squall line moving over the city on 7 December 2006 at approximately 11:02 GMT. Its intensity is estimated to have been T5 on the TORRO scale, equating to F2 on the Fujita scale.
The London Tornado of 1091 is the earliest reported tornado in England, occurring in London on Friday, 17 October 1091. It has been reckoned by modern assessment as possibly a T8 on the TORRO scale making it potentially the strongest recorded tornado in the British Isles, although this estimate is based on reports written 30 years after the tornado. The church of St Mary-le-Bow in the city of London was badly damaged; four rafters 26 feet (7.9 m) long were driven into the ground so that only 4 feet (1.2 m) protruded above the surface. Other churches in the area were demolished, as were over 600 houses. For all the damage inflicted, the tornado claimed just two known victims from a population of about 18,000. The tornado is mentioned in chronicles by Florence of Worcester and William of Malmesbury, the latter describing it as "a great spectacle for those watching from afar, but a terrifying experience for those standing near".
The European Severe Storms Laboratory (ESSL) is a scientific organisation that conducts research on severe convective storms, tornadoes, intense precipitation events, and avalanches across Europe and the Mediterranean. It operates the widely consulted European Severe Weather Database (ESWD).
This page documents the tornadoes and tornado outbreaks of 1981, primarily in the United States. Most tornadoes form in the U.S., although some events may take place internationally. Tornado statistics for older years like this often appear significantly lower than modern years due to fewer reports or confirmed tornadoes.
The following is a glossary of tornado terms. It includes scientific as well as selected informal terminology.
The 1981 United Kingdom tornado outbreak is regarded as the largest recorded tornado outbreak in European history. In the span of 5 hours and 26 minutes during the late morning and early afternoon of 23 November 1981, 104 confirmed tornadoes touched down across Wales and central, northern and eastern England.
The International Fujita scale rates the intensity of tornadoes and other wind events based on the severity of the damage they cause. It is used by the European Severe Storms Laboratory (ESSL) and various other organizations including Deutscher Wetterdienst (DWD) and State Meteorological Agency (AEMET). The scale is intended to be analogous to the Fujita and Enhanced Fujita scales, while being more applicable internationally by accounting for factors such as differences in building codes.
This page documents the tornadoes and tornado outbreaks of 1946, primarily in the United States. Most recorded tornadoes form in the U.S., although some events may take place internationally. Tornado statistics for older years like this often appear significantly lower than modern years due to fewer reports or confirmed tornadoes.
