A tornado is a violently rotating column of air which is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. In Optics, transparency (also called pellucidity) is the Material property of allowing Cumulonimbus (Cb is a type of Cloud that is tall dense and involved in Thunderstorms and other intense Weather. A cumulus cloud' is a type of Cloud with noticeable vertical development and clearly defined edges Tornadoes come in many sizes but are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud of debris. Condensation is the change of the physical state of aggregation (or simply state of matter from gaseous phase into liquid phase A funnel is a pipe with a wide often conical mouth and a narrow stem Debris (ˈdeɪbriː/ /dɛˈbriː is a word used to describe the remains of something that has been otherwise destroyed
Most tornadoes have wind speeds between 40 mph (64 km/h) and 110 mph (177 km/h), are approximately 250 feet (75 m) across, and travel a few miles (several kilometers) before dissipating. The kilometre ( American spelling: kilometer) symbol km is a unit of Length in the Metric system, equal to one thousand Some attain wind speeds of more than 300 mph (480 km/h), stretch more than a mile (1. 6 km) across, and stay on the ground for dozens of miles (more than 100 km). 
Although tornadoes have been observed on every continent except Antarctica, most occur in the United States. The United States of America —commonly referred to as the  They also commonly occur in southern Canada, south-central and eastern Asia, east-central South America, Southern Africa, northwestern and southeast Europe, Italy, western and southeastern Australia, and New Zealand. Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a Southern Africa is the Southernmost Region of the African Continent, variably defined by Geography or Geopolitics. Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest For a topic outline on this subject see List of basic Australia topics. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island 
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The word "tornado" is an altered form of the Spanish word tronada, which means "thunderstorm". This in turn was taken from the Latin tonare, meaning "to thunder". Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Thunder is the sound made by Lightning. Depending on the nature of the lightning and distance of the listener it can range from a sharp It most likely reached its present form through a combination of the Spanish tronada and tornar ("to turn"); however, this may be a folk etymology. Folk etymology is a term used in two distinct ways A commonly held misunderstanding of the origin of a particular word a False etymology.  A tornado is also commonly referred to as a twister, and is also sometimes referred to by the old-fashioned colloquial term cyclone. 
Most tornadoes take on the appearance of a narrow funnel, a few hundred yards (a few hundred meters) across, with a small cloud of debris near the ground. A funnel is a pipe with a wide often conical mouth and a narrow stem A cloud is a visible mass of droplets or frozen crystals floating in the atmosphere above the surface of the Earth or another Planetary body Debris (ˈdeɪbriː/ /dɛˈbriː is a word used to describe the remains of something that has been otherwise destroyed However, tornadoes can appear in many shapes and sizes.
Small, relatively weak landspouts may only be visible as a small swirl of dust on the ground. A landspout is a slang-term coined by meteorologist Howard B Bluestein in the early 1980s for a kind of Tornado not associated with the Mesocyclone of While the condensation funnel may not extend all the way to the ground, if associated surface winds are greater than 40 mph (64 km/h), the circulation is considered a tornado.  A tornado with a nearly cylindrical profile and relative low height is sometimes referred to as a stovepipe tornado. Large single-vortex tornadoes can look like large wedges stuck into the ground, and so are known as wedge tornadoes or wedges. A wedge is a triangular shaped tool a compound and portable Inclined plane, and one of the six classical Simple machines It can be used to separate The stovepipe classification is also used for this type of tornado, if it otherwise fits that profile. A wedge can be so wide that it appears to be a block of dark clouds, wider than the distance from the cloud base to the ground. Even experienced storm observers may not be able to tell the difference between a low-hanging cloud and a wedge tornado from a distance. Many, but not all major tornadoes are wedges. 
Tornadoes in the dissipating stage can resemble narrow tubes or ropes, and often curl or twist into complex shapes. These tornadoes are said to be roping out, or becoming a rope tornado. Multiple-vortex tornadoes can appear as a family of swirls circling a common center, or may be completely obscured by condensation, dust, and debris, appearing to be a single funnel. 
In addition to these appearances, tornadoes may be obscured completely by rain or dust. These tornadoes are especially dangerous, as even experienced meteorologists might not spot them. 
In the United States, on average tornadoes are around 500 feet (150 m) across, and stay on the ground for 5 miles (8 km). The United States of America —commonly referred to as the  Yet, there is an extremely wide range of tornado sizes, even for typical tornadoes. Weak tornadoes, or strong but dissipating tornadoes, can be exceedingly narrow, sometimes only a few feet across. A tornado was once reported to have a damage path only 7 feet (2 m) long.  On the other end of the spectrum, wedge tornadoes can have a damage path a mile (1. 6 km) wide or more. A tornado that affected Hallam, Nebraska on May 22, 2004 was at one point 2. Hallam Tornado Outbreak The Hallam Nebraska Tornado Outbreak was an outbreak of 56 Tornadoes in several Midwestern U Events 334 BC - The Greek army of Alexander the Great defeats Darius III of Persia in the Battle of the Granicus. "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " 5 miles (4 km) wide at the ground. 
In terms of path length, the Tri-State Tornado, which affected parts of Missouri, Illinois, and Indiana on March 18, 1925, was officially on the ground continuously for 219 miles (352 km). The Great Tri-State Tornado of Wednesday March 18, 1925, crossed from southeastern Missouri, through southern Illinois, then into southwestern Missouri ( or) is a state in the Midwestern region of the United States bordered by Iowa, Illinois, Kentucky, Tennessee The State of Illinois ( roughly ill-i-NOY is a state of the United States of America, the 21st to be admitted to the Union. The State of Indiana ( was the 19th US state admitted into the union Events 37 - The Roman Senate annuls Tiberius ' will and proclaims Caligula emperor Year 1925 ( MCMXXV) was a Common year starting on Thursday (link will display the full calendar of the Gregorian calendar. Many tornadoes which appear to have path lengths of 100 miles (160 km) or longer are actually a family of tornadoes which have formed in quick succession; however, there is no substantial evidence that this occurred in the case of the Tri-State Tornado.  In fact, modern reanalysis of the path suggests that the tornado began 15 miles (24 km) further west than previously thought. 
Tornadoes can have a wide range of colors, depending on the environment in which they form. Those which form in a dry environment can be nearly invisible, marked only by swirling debris at the base of the funnel. Condensation funnels which pick up little or no debris can be gray to white. While travelling over a body of water as a waterspout, they can turn very white or even blue. Funnels which move slowly, ingesting a lot of debris and dirt, are usually darker, taking on the color of debris. Tornadoes in the Great Plains can turn red because of the reddish tint of the soil, and tornadoes in mountainous areas can travel over snow-covered ground, turning brilliantly white. The Great Plains are the broad expanse of Prairie and Steppe which lie east of the Rocky Mountains in the United States and Canada 
Lighting conditions are a major factor in the appearance of a tornado. A tornado which is "back-lit" (viewed with the sun behind it) appears very dark. In the context of Lighting design, backlighting refers to the process of Illuminating the subject from the back The same tornado, viewed with the sun at the observer's back, may appear gray or brilliant white. Tornadoes which occur near the time of sunset can be many different colors, appearing in hues of yellow, orange, and pink. 
Dust kicked up by the winds of the parent thunderstorm, heavy rain and hail, and the darkness of night are all factors which can reduce the visibility of tornadoes. Tornadoes occurring in these conditions are especially dangerous, since only weather radar observations, or possibly the sound of an approaching tornado, serve as any warning to those in the storm's path. A weather radar is a type of Radar used to locate precipitation, calculate its motion estimate its type ( Rain Fortunately most significant tornadoes form under the storm's rain-free base, or the area under the thunderstorm's updraft, where there is little or no rain. In addition, most tornadoes occur in the late afternoon, when the bright sun can penetrate even the thickest clouds.  Also, night-time tornadoes are often illuminated by frequent lightning.
There is mounting evidence, including Doppler On Wheels mobile radar images and eyewitness accounts, that most tornadoes have a clear, calm center with extremely low pressure, akin to the eye of tropical cyclones. Doppler On Wheels (or DOW is a project maintained by the Center for Severe Weather Research led by Joshua Wurman, with the funding mainly provided by the The eye is a region of mostly calm Weather found at the center of strong Tropical cyclones The eye of a Storm is a roughly circular area and typically 30–65 km A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding This area would be clear (possibly full of dust), have relatively light winds, and be very dark, since the light would be blocked by swirling debris on the outside of the tornado. Lightning is said to be the source of illumination for those who claim to have seen the interior of a tornado. 
Tornadoes normally rotate cyclonically in direction (counterclockwise in the northern hemisphere, clockwise in the southern). In Meteorology, a cyclone refers to an area of closed circular fluid motion rotating in the same direction as the Earth. Northern Hemisphere is the half of a Planet that is North of the Equator —the word hemisphere literally means 'half ball' Southern Hemisphere is the half of a Planet that is South of the Equator —the word hemisphere literally means 'half ball' While large-scale storms always rotate cyclonically due to the Coriolis effect, thunderstorms and tornadoes are so small that the direct influence of Coriolis effect is inconsequential, as indicated by their large Rossby numbers. In physics the Coriolis effect is an apparent deflection of moving objects when they are viewed from a Rotating frame of reference. The Rossby number, named for Carl-Gustav Arvid Rossby, is a Dimensionless number used in describing fluid flow Supercells and tornadoes rotate cyclonically in numerical simulations even when the Coriolis effect is neglected.  Low-level mesocyclones and tornadoes owe their rotation to complex processes within the supercell and ambient environment. A mesocyclone is a Vortex of air approximately 2 to 10 km in diameter (the Mesoscale of meteorology within a convective Storm 
Approximately 1% of tornadoes rotate in an anticyclonic direction. Typically, only landspouts and gustnados rotate anticyclonically, and usually only those which form on the anticyclonic shear side of the descending rear flank downdraft in a cyclonic supercell. The rear flank downdraft or RFD is a region of dry air wrapping around the back of a Mesocyclone in a Supercell thunderstorm  However, on rare occasions, anticyclonic tornadoes form in association with the mesoanticyclone of an anticyclonic supercell, in the same manner as the typical cyclonic tornado, or as a companion tornado—either as a satellite tornado or associated with anticyclonic eddies within a supercell. An anticyclonic tornado is a Tornado which rotates in a Clockwise direction in the Northern Hemisphere and a Counterclockwise direction in the 
Tornadoes emit widely on the acoustics spectrum and the sounds are caused by multiple mechanisms. Acoustics is the interdisciplinary science that deals with the study of Sound, Ultrasound and Infrasound (all mechanical waves in gases liquids and solids An audio frequency (abbreviation AF) or audible frequency is characterized as a periodic vibration whose Frequency is audible to the average human Various sounds of tornadoes have been reported throughout time, mostly related to familiar sounds for the witness and generally some variation of a whooshing roar. Popularly reported sounds include a freight train, rushing rapids or waterfall, a jet engine from close proximity, or combinations of these. A train is a connected series of vehicles that move along a track ( Permanent way) to transport freight or passengers from one place to another A waterfall is usually a geological formation resulting from water often in the form of a Stream, flowing over an Erosion -resistant rock specific --->A jet engine is a Reaction engine that discharges a fast moving jet of Fluid to Many tornadoes are not audible from much distance; the nature and propagation distance of the audible sound depends on atmospheric conditions and topography.
The winds of the tornado vortex and of constituent turbulent eddies, as well as airflow interaction with the surface and debris, contribute to the sounds. In Fluid dynamics, turbulence or turbulent flow is a fluid regime characterized by chaotic Stochastic property changes In Fluid dynamics, an eddy is the swirling of a Fluid and the reverse current created when the fluid flows past an obstacle Funnel clouds also produce sounds. Funnel clouds and small tornadoes are reported as whistling, whining, humming, or the buzzing of innumerable bees or electricity, or more or less harmonic, whereas many tornadoes are reported as a continuous, deep rumbling, or an irregular sound of “noise”. Bees are flying Insects closely related to Wasps and Ants Bees are a Monophyletic lineage within the superfamily Apoidea 
Since many tornadoes are audible only in very close proximity, sound is not reliable warning of a tornado. And, any strong, damaging wind, even a severe hail volley or continuous thunder in a thunderstorm may produce a roaring sound. 
Tornadoes also produce identifiable inaudible infrasonic signatures. Infrasound is Sound with a Frequency too low to be heard by the human Ear.  Unlike audible signatures, tornadic signatures have been isolated; due to the long distance propagation of low-frequency sound, efforts are ongoing to develop tornado prediction and detection devices with additional value in understanding tornado morphology, dynamics, and creation.  Tornadoes also produce a detectable seismic signature, and research continues on isolating it and understanding the process. Seismology (from Greek grc σεισμός seismos, "earthquake" and grc -λογία -logia) is the scientific study of Earthquakes 
Tornadoes emit on the electromagnetic spectrum, for example, with sferics and E-field effects detected. The electromagnetic (EM spectrum is the range of all possible Electromagnetic radiation frequencies A Radio Atmospheric signal or Sferic (sometimes also spelled "Spheric" is a Broadband Electromagnetic impulse that occurs as a result of In Physics, the space surrounding an Electric charge or in the presence of a time-varying Magnetic field has a property called an electric field (that can  The effects vary, mostly with little observed consistency.
Correlations with patterns of lightning activity have also been observed, but little in way of consistent correlations have been advanced. Lightning is an atmospheric discharge of Electricity, which typically occurs during Thunderstorms and sometimes during volcanic eruptions or Tornadic storms do not contain more lightning than other storms, and some tornadic cells never contain lightning. More often than not, overall cloud-to-ground (CG) lightning activity decreases as a tornado reaches the surface and returns to the baseline level when the tornado lifts. In many cases, very intense tornadoes and thunderstorms exhibit an increased and anomalous dominance in positive polarity CG discharges.  Electromagnetics and lightning have little to nothing to do directly with what drives tornadoes (tornadoes are basically a thermodynamic phenomenon), though there are likely connections with the storm and environment affecting both phenomena. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of In Physics, thermodynamics (from the Greek θερμη therme meaning " Heat " and δυναμις dynamis meaning "
Luminosity has been reported in the past, and is probably due to misidentification of external light sources such as lightning, city lights, and power flashes from broken lines, as internal sources are now uncommonly reported and are not known to ever been recorded. Luminosity has different meanings in several different fields of science
In addition to winds, tornadoes also exhibit changes in atmospheric variables such as temperature, moisture, and pressure. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature For example, on June 24, 2003 near Manchester, South Dakota, a probe measured a 100 mbar (hPa) (2. Events 972 - Battle of Cedynia, the first documented victory of Polish forces takes place Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. Manchester was a small unincorporated community in Kingsbury County in the east-central part of the U The bar (symbol bar) decibar (symbol dbar) and the millibar (symbol mbar, also mb are units of Pressure. 95 inHg) pressure deficit. Inches of mercury, inHg or "Hg is a measuring unit for Pressure. The pressure dropped gradually as the vortex approached then dropped extremely rapidly to 850 mbar (hPa) (25. The bar (symbol bar) decibar (symbol dbar) and the millibar (symbol mbar, also mb are units of Pressure. 10 inHg) in the core of the violent tornado before rising rapidly as the vortex moved away, resulting in a V-shape pressure trace. Inches of mercury, inHg or "Hg is a measuring unit for Pressure. Temperature tends to decrease and moisture content to increase in the immediate vicinity of a tornado. 
Tornadoes often develop from a class of thunderstorms known as supercells. Tornadogenesis is the process by which a Tornado forms There are many types of tornadoes and each type of tornado can have several different methods of formation A supercell is a severe thunderstorm with a deep continuously rotating updraft (a Mesocyclone) A supercell is a severe thunderstorm with a deep continuously rotating updraft (a Mesocyclone) Supercells contain mesocyclones, an area of organized rotation a few miles up in the atmosphere, usually 1–6 miles (2–10 km) across. A mesocyclone is a Vortex of air approximately 2 to 10 km in diameter (the Mesoscale of meteorology within a convective Storm Most intense tornadoes (EF3 to EF5 on the Enhanced Fujita Scale) develop from supercells. The Enhanced Fujita Scale, or EF Scale, is the scale for rating the strength of Tornadoes in the United States estimated via the damage they cause In addition to tornadoes, very heavy rain, frequent lightning, strong wind gusts, and hail are common in such storms.
Most tornadoes from supercells follow a recognizable life cycle.  That begins when increasing rainfall drags with it an area of quickly descending air known as the rear flank downdraft (RFD). The rear flank downdraft or RFD is a region of dry air wrapping around the back of a Mesocyclone in a Supercell thunderstorm This downdraft accelerates as it approaches the ground, and drags the supercell's rotating mesocyclone towards the ground with it.
As the mesocyclone approaches the ground, a visible condensation funnel appears to descend from the base of the storm, often from a rotating wall cloud. A wall cloud, or pedestal cloud, is a Cloud formation associated with Thunderstorms It is a marked lowering typically beneath the rain-free base (RFB As the funnel descends, the RFD also reaches the ground, creating a gust front that can cause damage a good distance from the tornado. Usually, the funnel cloud becomes a tornado within minutes of the RFD reaching the ground.
Initially, the tornado has a good source of warm, moist inflow to power it, so it grows until it reaches the mature stage. This can last anywhere from a few minutes to more than an hour, and during that time a tornado often causes the most damage, and in rare cases can be more than one mile (1. 6 km) across. Meanwhile, the RFD, now an area of cool surface winds, begins to wrap around the tornado, cutting off the inflow of warm air which feeds the tornado.
As the RFD completely wraps around and chokes off the tornado's air supply, the vortex begins to weaken, and become thin and rope-like. This is the dissipating stage; often lasting no more than a few minutes, after which the tornado fizzles. During this stage the shape of the tornado becomes highly influenced by the winds of the parent storm, and can be blown into fantastic patterns. 
As the tornado enters the dissipating stage, its associated mesocyclone often weakens as well, as the rear flank downdraft cuts off the inflow powering it. In particularly intense supercells tornadoes can develop cyclically. As the first mesocyclone and associated tornado dissipate, the storm's inflow may be concentrated into a new area closer to the center of the storm. If a new mesocyclone develops, the cycle may start again, producing one or more new tornadoes. Occasionally, the old (occluded) mesocyclone and the new mesocyclone produce a tornado at the same time.
Though this is a widely-accepted theory for how most tornadoes form, live, and die, it does not explain the formation of smaller tornadoes, such as landspouts, long-lived tornadoes, or tornadoes with multiple vortices. These each have different mechanisms which influence their development—however, most tornadoes follow a pattern similar to this one. 
The Fujita scale and the Enhanced Fujita Scale rate tornadoes by damage caused. Tornadoes vary in intensity regardless of shape size and location The Fujita scale ( F-Scale) or Fujita-Pearson scale, is a scale for rating Tornado intensity based on the damage tornadoes inflict on human-built structures The Enhanced Fujita Scale, or EF Scale, is the scale for rating the strength of Tornadoes in the United States estimated via the damage they cause The Enhanced Fujita Scale was an upgrade to the older Fujita scale, with engineered (by expert elicitation) wind estimates and better damage descriptions, but was designed so that a tornado rated on the Fujita scale would receive the same numerical rating. In Science, Engineering, and Research, expert elicitation is the synthesis of opinions of Experts of a subject where there is uncertainty due An EF0 tornado will likely damage trees but not substantial structures, whereas an EF5 tornado can rip buildings off their foundations leaving them bare and even deform large skyscrapers. A skyscraper is a tall continuously habitable Building. There is no official definition or a precise cutoff height above which a building may clearly be classified as a skyscraper The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. The TORRO tornado intensity scale (or T-Scale) is a scale measuring Tornado intensity between T0 and T11 Doppler radar data, photogrammetry, and ground swirl patterns (cycloidal marks) may also be analyzed to determine intensity and award a rating. Pulse-Doppler is a Radar system capable of not only detecting target location (bearing range and altitude but also measuring its radial velocity (range-rate A weather radar is a type of Radar used to locate precipitation, calculate its motion estimate its type ( Rain Photogrammetry is the first Remote sensing technology ever developed in which geometric properties about objects are determined from photographic images
Tornadoes vary in intensity regardless of shape, size, and location, though strong tornadoes are typically larger than weak tornadoes. The association with track length and duration also varies, although longer track tornadoes tend to be stronger.  In the case of violent tornadoes, only a small portion of the path is of violent intensity, most of the higher intensity from subvortices. A multiple vortex tornado is a Tornado that contains several vortices rotating around inside of and as part of the main Vortex. 
In the United States, 80% of tornadoes are EF0 and EF1 (T0 through T3) tornadoes. The rate of occurrence drops off quickly with increasing strength—less than 1% are violent tornadoes, stronger than EF4, T8. 
Outside the United States, areas in south-central Asia, and perhaps portions of southeastern South America and southern Africa, violent tornadoes are extremely rare. This is apparently mostly due to the lesser number of tornadoes overall, as research shows that tornado intensity distributions are fairly similar worldwide. A few significant tornadoes occur annually in Europe, Asia, southern Africa, and southeastern South America, respectively. 
The United States has the most tornadoes of any country, about four times more than estimated in all of Europe, not including waterspouts.  This is mostly due to the unique geography of the continent. North America is a relatively large continent that extends from the tropical south into arctic areas, and has no major east-west mountain range to block air flow between these two areas. The Tropics are centered on the Equator and limited in Latitude by the Tropic of Cancer in the northern hemisphere at approximately 23°26' (23 The Arctic is the Region around the Earth 's North Pole, opposite the Antarctic region around the South Pole. In the middle latitudes, where most tornadoes of the world occur, the Rocky Mountains block moisture and atmospheric flow, allowing drier air at mid-levels of the troposphere, and causing cyclogenesis downstream to the east of the mountains. The middle latitudes are between 33 degrees 33' 33" North and 66 degrees 33' 33" and 64 degrees 33' 33" South and 33 degrees 33' 33" South Latitude, or Mountain peaks of the Rocky Mountains The Rocky Mountains, often called the Rockies, are a Mountain range in western North America. The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 75% of the atmosphere's mass and almost all of its Water vapor and Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere (a low pressure area The desert Southwest also feeds drier air and the dry line, while the Gulf of Mexico fuels abundant low-level moisture. A dry line, (also called dew point line, or Marfa front) is an important factor in Severe weather frequency in the Great Plains of The Gulf of Mexico ( Spanish: Golfo de México) is the ninth largest Body of water in the world This unique topography allows for many collisions of warm and cold air, the conditions that breed strong, long-lived storms many times a year. A large portion of these tornadoes form in an area of the central United States known as Tornado Alley. The Central United States is sometimes conceived as between the Eastern United States and Western United States as part of a three-region model roughly coincident For the book by William S Burroughs, see Tornado Alley (book.  This area extends into Canada, particularly Ontario and the Prairie Provinces. Ontario (ɒnˈtɛrioʊ is a province located in the central part of Canada, the largest by population and second largest after Quebec The Canadian Prairies is a region in western Canada, which may correspond to several different definitions natural or political Strong tornadoes also occasionally occur in northern Mexico. The United Mexican States ( or commonly Mexico (ˈmɛksɪkoʊ () is a federal constitutional Republic in North America.
The United States averages about 1,200 tornadoes per year. The Netherlands has the highest average number of recorded tornadoes per area of any country (more than 20, or 0. The Netherlands ( Dutch:, ˈnedərlɑnt is the European part of the Kingdom of the Netherlands, which consists of the Netherlands the Netherlands 0013 per sq mi (0. 00048 per km²), annually), followed by the UK (around 33, or 0. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located 00035 per sq mi (0. 00013 per km²), per year), but most are small and cause minor damage. In absolute number of events, ignoring area, the UK experiences more tornadoes than any other European country, excluding waterspouts. 
Bangladesh and surrounding areas of eastern India suffer from tornadoes of equal severity to those in the US, and occurring more frequently than anywhere else in the world, but such events are under-reported due to the scarcity of media coverage in third-world countries. ( Bengali: বাংলাদেশ inc-Latn Bangladesh) officially India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country Tornados kill about 179 people per year in Bangladesh, many more than in the US. This is due to high population density, poor quality of construction, lack of tornado safety knowledge, and other factors.  Other areas of the world that have frequent tornadoes include South Africa, parts of Argentina, Paraguay, and southern Brazil, as well as portions of Europe, Australia and New Zealand, and far eastern Asia. The Republic of South Africa (also known by other official names) is a country located at the southern tip of the continent of Africa For a topic outline on this subject see List of basic Argentina topics. Paraguay, officially the Republic of Paraguay ( Spanish: República del Paraguay; Guaraní: Tetã Paraguái) is one of the only |utc_offset = -2 to -4 |time_zone_DST = BRST |utc_offset_DST = -2 to -5 |cctld For a topic outline on this subject see List of basic Australia topics. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island 
Tornadoes are most common in spring and least common in winter.  Since autumn and spring are transitional periods (warm to cool and vice versa) there are more chances of cooler air meeting with warmer air, resulting in thunderstorms. Tornadoes can also be caused by landfalling tropical cyclones, which tend to occur in the late summer and autumn. Landfall is the event of a Tropical cyclone (also known as a hurricane or a Waterspout coming onto Land after being over water A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding But favorable conditions can occur at any time of the year.
Tornado occurrence is highly dependent on the time of day, because of solar heating.  Worldwide, most tornadoes occur in the late afternoon, between 3 and 7 pm local time, with a peak near 5 pm.  However, destructive tornadoes can occur at any time of day. The Gainesville Tornado of 1936, one of the deadliest tornadoes in history, occurred at 8:30 am local time. The Tupelo-Gainesville Outbreak was an outbreak of seventeen Tornadoes that struck the Southeastern United States from April 5 to 6th 1936 
Associations to various climate and environmental trends exist. Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of For example, an increase in the sea surface temperature of source region (e. Sea surface temperature (SST is the water Temperature close to the surface g. Gulf of Mexico and Mediterranean Sea) increases moisture content, potentially fueling an increase in severe weather and tornado activity, particularly in the cool season. 
Although insufficient support exists to make conclusions, evidence does suggest that the Southern Oscillation is weakly correlated with some changes in tornado activity; which vary by season and region as well as whether the ENSO phase is that of El Niño or La Niña. El Niño-Southern Oscillation ( ENSO; commonly referred to as simply El Niño) is a global coupled ocean-atmosphere phenomenon El Niño-Southern Oscillation ( ENSO; commonly referred to as simply El Niño) is a global coupled ocean-atmosphere phenomenon El Niño-Southern Oscillation ( ENSO; commonly referred to as simply El Niño) is a global coupled ocean-atmosphere phenomenon El Niño-Southern Oscillation ( ENSO; commonly referred to as simply El Niño) is a global coupled ocean-atmosphere phenomenon 
Climatic shifts affect tornadoes via teleconnections in shifting the jet stream and the larger weather patterns. Teleconnection in Atmospheric science refers to climate anomalies being related to each other at large distances (typically thousands of kilometers The climate-tornado link is confounded by the forces affecting larger patterns and by the local, nuanced nature of tornadoes. Although it is reasonable that the climate change phenomenon of global warming may affect tornado activity, any such effect is not yet identifiable due to the complexity, local nature of the storms, and database quality issues. Climate change is any long-term significant change in the “average weather” that a given region experiences Global warming is the increase in the average measured temperature of the Any effect would vary by region. 
Weather forecasting is handled regionally by many national and international agencies. Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location For the most part, they are also in charge of the prediction of conditions conducive to tornado development.
Severe thunderstorm warnings are provided to Australia by the Bureau of Meteorology. The Bureau of Meteorology is an Executive Agency of the Australian Government responsible for providing weather services to Australia and surrounding areas The country is in the middle of an upgrade to Doppler radar systems, with their first benchmark of installing six new radars reached in July 2006. Pulse-Doppler is a Radar system capable of not only detecting target location (bearing range and altitude but also measuring its radial velocity (range-rate A weather radar is a type of Radar used to locate precipitation, calculate its motion estimate its type ( Rain 
The European Union founded a project in 2002 called the European Severe Storms virtual Laboratory, or ESSL, which is meant to fully document tornado occurrence across the continent. The European Union ( EU) is a political and economic union of twenty-seven member states, located primarily in The ESTOFEX (European Storm Forecast Experiment) arm of the project also issues one day forecasts for severe weather likelihood.  In Germany, Austria, and Switzerland, an organization known as TorDACH collects information regarding tornadoes, waterspouts, and downbursts from Germany, Austria, and Switzerland. A secondary goal is collect all severe weather information. This project is meant to fully document severe weather activity in these three countries. 
In the United Kingdom, the Tornado and Storm Research Organisation (TORRO) makes experimental predictions. For the tornado scale developed by TORRO see TORRO scale. The Tornado and Storm Research Organisation (TORRO was founded by Terence Meaden The Met Office provides official forecasts for the UK. For the UKMET model see Tropical cyclone forecast model. The Met Office (originally an abbreviation for Meteorological Office,
In the United States, generalized severe weather predictions are issued by the Storm Prediction Center, based in Norman, Oklahoma. The Storm Prediction Center (SPC located in Norman, Oklahoma, is part of the National Centers for Environmental Prediction (NCEP operating under Norman is the largest city in and the County seat of Cleveland County in the U For the next one, two, and three days, respectively, they will issue categorical and probabilistic forecasts of severe weather, including tornadoes. There is also a more general forecast issued for the four to eight day period. Just prior to the expected onset of an organized severe weather threat, SPC issues severe thunderstorm and tornado watches, in collaboration with local National Weather Service offices. The National Weather Service ( NWS) once known as the Weather Bureau is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration Warnings are issued by local National Weather Service offices when a severe thunderstorm or tornado is occurring or imminent. This article describes the United States National Weather Service (NWS
In Japan, predictions and study of tornadoes in Japan are handled by the Japan Meteorological Agency. The or JMA, is the Japanese government's Weather service Charged with gathering and reporting weather data and forecasts in Japan it is a semi-autonomous In Canada, weather forecasts and warnings, including tornadoes, are produced by the seven regional offices of the Meteorological Service of Canada, a division of Environment Canada. The Meteorological Service of Canada (MSC is a division of Environment Canada, which primarily provides public meteorological information and Weather forecasts Environment Canada (EC, legally incorporated as the Department of the Environment under the Department of the Environment Act ( R
Rigorous attempts to warn of tornadoes began in the United States in the mid-20th century. Before the 1950s, the only method of detecting a tornado was by someone seeing it on the ground. Often, news of a tornado would reach a local weather office after the storm.
However, with the advent of weather radar, areas near a local office could get advance warning of severe weather. A weather radar is a type of Radar used to locate precipitation, calculate its motion estimate its type ( Rain The first public tornado warnings were issued in 1950 and the first tornado watches and convective outlooks in 1952. A tornado warning is an alert issued by government weather services to warn an area that a Tornado may be Imminent. See Severe weather terminology for a comprehensive article on related weather terms The Storm Prediction Center (SPC located in Norman, Oklahoma, is part of the National Centers for Environmental Prediction (NCEP operating under In 1953 it was confirmed that hook echoes are associated with tornadoes. The hook echo is one of the classical hallmarks of Tornado -producing Supercell Thunderstorms as seen on Weather radar. By recognizing these radar signatures, meteorologists could detect thunderstorms likely producing tornadoes from dozens of miles away. 
In the mid 1970s, the US National Weather Service (NWS) increased its efforts to train storm spotters to spot key features of storms which indicate severe hail, damaging winds, and tornadoes, as well as damage itself and flash flooding. A storm spotter is a specific type of Weather spotter who actively maintains a visual watch of the development and progression of specific weather events while actively relaying A flash flood is a rapid flooding of geomorphic lowlying areas - washes rivers and streams The program was called Skywarn, and the spotters were local sheriff's deputies, state troopers, firefighters, ambulance drivers, amateur radio operators, civil defense (now emergency management) spotters, storm chasers, and ordinary citizens. SKYWARN is a program of the United States ' National Weather Service (NWS SHERIFF is a telecom fraud detection and management system originally developed by BT and MCI. State police are a type of sub-national Territorial police force, particularly in Australia and the United States. Firefighters are rescuers extensively trained primarily to put out hazardous Fires that threaten civilian populations and property to rescue people from car accidents collapsed The Emergency Medical Technician ( EMT) exists in many countries and is a health care provider trained to provide prehospital emergency medical care See also Amateur radio An amateur radio operator is an individual who typically uses equipment at an Amateur radio station to engage in two-way Civil defense or civil defence (see spelling differences) is an effort to prepare Civilians for Military attack Emergency management (or disaster management) is the discipline of dealing with and avoiding risks When severe weather is anticipated, local weather service offices request that these spotters look out for severe weather, and report any tornadoes immediately, so that the office can issue a timely warning.
Usually spotters are trained by the NWS on behalf of their respective organizations, and report to them. The organizations activate public warning systems such as sirens and the Emergency Alert System, and forward the report to the NWS. A civil defense siren (also referred to as an air raid siren, tornado siren, tsunami siren, or other outdoor warning siren and also rarely referred The Emergency Alert System (EAS is a national warning system in the U  There are more than 230,000 trained Skywarn weather spotters across the United States. 
In Canada, a similar network of volunteer weather watchers, called Canwarn, helps spot severe weather, with more than 1,000 volunteers. Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page The Canwarn program is an organized severe weather spotting and reporting program organized and run by the Meteorological Services Division of Environment Canada.  In Europe, several nations are organizing spotter networks under the auspices of Skywarn Europe and the Tornado and Storm Research Organisation (TORRO) has maintained a network of spotters in the United Kingdom since the 1970s. For the tornado scale developed by TORRO see TORRO scale. The Tornado and Storm Research Organisation (TORRO was founded by Terence Meaden The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located
Storm spotters are needed because radar systems such as NEXRAD do not detect a tornado; only indications of one. NEXRAD or Nexrad ( Nex t-Generation Rad ar is a network of 158 high-resolution Doppler Weather radars operated by the National Weather Radar may give a warning before there is any visual evidence of a tornado or imminent tornado, but ground truth from an observer can either verify the threat or determine that a tornado is not imminent. Ground truth is a term used in Cartography, Meteorology, analysis of aerial photographs, Satellite imagery and a range of other Remote The spotter's ability to see what radar cannot is especially important as distance from the radar site increases, because the radar beam becomes progressively higher in altitude further away from the radar, chiefly due to curvature of Earth, and the beam also spreads out. Therefore, when far from a radar, only high in the storm is observed and the important areas are not sampled, and data resolution also suffers. Also, some meteorological situations leading to tornadogenesis are not readily detectable by radar and on occasion tornado development may occur more quickly than radar can complete a scan and send the batch of data.
Storm spotters are trained to discern whether a storm seen from a distance is a supercell. A supercell is a severe thunderstorm with a deep continuously rotating updraft (a Mesocyclone) They typically look to its rear, the main region of updraft and inflow. An updraft or downdraft ( air pocket) is the vertical movement of Air as a Weather related phenomenon Under the updraft is a rain-free base, and the next step of tornadogenesis is the formation of a rotating wall cloud. Tornadogenesis is the process by which a Tornado forms There are many types of tornadoes and each type of tornado can have several different methods of formation A wall cloud, or pedestal cloud, is a Cloud formation associated with Thunderstorms It is a marked lowering typically beneath the rain-free base (RFB The vast majority of intense tornadoes occur with a wall cloud on the backside of a supercell. 
Evidence of a supercell comes from the storm's shape and structure, and cloud tower features such as a hard and vigorous updraft tower, a persistent, large overshooting top, a hard anvil (especially when backsheared against strong upper level winds), and a corkscrew look or striations. Cumulonimbus (Cb is a type of Cloud that is tall dense and involved in Thunderstorms and other intense Weather. An overshooting top is a domed structure shooting out of the anvil of a Thunderstorm, sometimes into the Stratosphere. Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) Striations means a series of Ridges, furrows or Linear marks and are used in several ways Glacial striation Striation (geology Under the storm and closer to where most tornadoes are found, evidence of a supercell and likelihood of a tornado includes inflow bands (particularly when curved) such as a "beaver tail", and other clues such as strength of inflow, warmth and moistness of inflow air, how outflow- or inflow-dominant a storm appears, and how far is the front flank precipitation core from the wall cloud. Tornadogenesis is most likely at the interface of the updraft and rear flank downdraft, and requires a balance between the outflow and inflow. The rear flank downdraft or RFD is a region of dry air wrapping around the back of a Mesocyclone in a Supercell thunderstorm 
Only wall clouds that rotate spawn tornadoes, and usually precede the tornado by five to thirty minutes. Rotating wall clouds are the visual manifestation of a mesocyclone. A mesocyclone is a Vortex of air approximately 2 to 10 km in diameter (the Mesoscale of meteorology within a convective Storm Barring a low-level boundary, tornadogenesis is highly unlikely unless a rear flank downdraft occurs, which is usually visibly evidenced by evaporation of cloud adjacent to a corner of a wall cloud. The rear flank downdraft or RFD is a region of dry air wrapping around the back of a Mesocyclone in a Supercell thunderstorm A cloud is a visible mass of droplets or frozen crystals floating in the atmosphere above the surface of the Earth or another Planetary body A tornado often occurs as this happens or shortly after; first, a funnel cloud dips and in nearly all cases by the time it reaches halfway down, a surface swirl has already developed, signifying a tornado is on the ground before condensation connects the surface circulation to the storm. A funnel cloud is a Funnel -shaped Cloud of condensed Water droplets associated with a rotating column of air and extending from the base of Tornadoes may also occur without wall clouds, under flanking lines, and on the leading edge. Spotters watch all areas of a storm, and the cloud base and surface. This article refers to meteorology for the airborne base of Captain Scarlet see Cloudbase. 
Today, most developed countries have a network of weather radars, which remains the main method of detecting signatures likely associated with tornadoes. A weather radar is a type of Radar used to locate precipitation, calculate its motion estimate its type ( Rain In the United States and a few other countries, Doppler radar stations are used. Pulse-Doppler is a Radar system capable of not only detecting target location (bearing range and altitude but also measuring its radial velocity (range-rate A weather radar is a type of Radar used to locate precipitation, calculate its motion estimate its type ( Rain These devices measure the velocity and radial direction (towards or away from the radar) of the winds in a storm, and so can spot evidence of rotation in storms from more than a hundred miles (160 km) away. Direction is the information contained in the relative position of one point with respect to another point without the Distance information
Also, most populated areas on Earth are now visible from the Geostationary Operational Environmental Satellites (GOES), which aid in the nowcasting of tornadic storms. The Geostationary Operational Environmental Satellite (or GOES) program is a key element in United States' National Weather Service (NWS operations Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location 
The most extreme tornado in recorded history was the Tri-State Tornado which roared through parts of Missouri, Illinois, and Indiana on March 18, 1925. This is a list of some Tornado records. Tornado outbreaks Most tornadoes in single outbreak The Super Outbreak of April 3-4 1974 spawned The Great Tri-State Tornado of Wednesday March 18, 1925, crossed from southeastern Missouri, through southern Illinois, then into southwestern Missouri ( or) is a state in the Midwestern region of the United States bordered by Iowa, Illinois, Kentucky, Tennessee The State of Illinois ( roughly ill-i-NOY is a state of the United States of America, the 21st to be admitted to the Union. The State of Indiana ( was the 19th US state admitted into the union Events 37 - The Roman Senate annuls Tiberius ' will and proclaims Caligula emperor Year 1925 ( MCMXXV) was a Common year starting on Thursday (link will display the full calendar of the Gregorian calendar. It was likely an F5, though tornadoes were not ranked on any scale in that era. It holds records for longest path length (219 miles, 352 km), longest duration (about 3. 5 hours), and fastest forward speed for a significant tornado (73 mph, 117 km/h) anywhere on earth. In addition, it is the deadliest single tornado in United States history (695 dead).  It was also the second costliest tornado in history at the time, but has been surpassed by several others non-normalized. When costs are normalized for wealth and inflation, it still ranks third today. 
The deadliest tornado in world history was the Daultipur-Salturia Tornado in Bangladesh on April 26, 1989, which killed approximately 1300 people. The Daulatpur-Saturia Bangladesh Tornado was an extremely destructive Tornado that occurred in the Manikganj District, Bangladesh on April 26 ( Bengali: বাংলাদেশ inc-Latn Bangladesh) officially Events 1467 - The miraculous image in Our Lady of Good Counsel appear in Genazzano, Italy. Year 1989 ( MCMLXXXIX) was a Common year starting on Sunday (link displays 1989 Gregorian calendar) 
The most extensive tornado outbreak on record, in almost every category, was the Super Outbreak, which affected a large area of the central United States and extreme southern Ontario in Canada on April 3 and April 4, 1974. While there is no single agreed upon definition generally more than six Tornadoes in a day in the same region is considered a tornado outbreak. The Super Outbreak is the largest Tornado outbreak on record for a single 24-hour period Ontario (ɒnˈtɛrioʊ is a province located in the central part of Canada, the largest by population and second largest after Quebec Events 1043 - Edward the Confessor is crowned King of England. Events 1581 - Francis Drake completes a circumnavigation of the world and is knighted by Elizabeth I. Year 1974 ( MCMLXXIV) was a Common year starting on Tuesday (link will display full calendar of the 1974 Gregorian calendar. Not only did this outbreak feature an incredible 148 tornadoes in only 18 hours, but an unprecedented number of them were violent; six were of F5 intensity, and twenty-four F4. This outbreak had a staggering sixteen tornadoes on the ground at the same time at the peak of the outbreak. More than 300 people, possibly as many as 330, were killed by tornadoes during this outbreak. 
While it is nearly impossible to directly measure the most violent tornado wind speeds (conventional anemometers would be destroyed by the intense winds), some tornadoes have been scanned by mobile Doppler radar units, which can provide a good estimate of the tornado's winds. An anemometer is a device for measuring wind speed and is one instrument used in a Weather station. Doppler On Wheels (or DOW is a project maintained by the Center for Severe Weather Research led by Joshua Wurman, with the funding mainly provided by the The highest wind speed ever measured in a tornado, which is also the highest wind speed ever recorded on the planet, is 301 ± 20 mph (484 ± 32 km/h) in the F5 Moore, Oklahoma tornado. Moore is a sprawling residential city in Cleveland County, Oklahoma and is part of the Oklahoma City Metropolitan Area Though the reading was taken about 100 feet (30 m) above the ground, this is a testament to the power of the strongest tornadoes. 
Storms which produce tornadoes can feature intense updrafts, sometimes exceeding 150 mph (240 km/h). Debris from a tornado can be lofted into the parent storm and carried a very long distance. A tornado which affected Great Bend, Kansas in November, 1915 was an extreme case, where a "rain of debris" occurred 80 miles (130 km) from the town, a sack of flour was found 110 miles (177 km) away, and a cancelled check from the Great Bend bank was found in a field outside of Palmyra, Nebraska, 305 miles (491 km) to the northeast. Great Bend is a City situated along the Arkansas River in the southwestern part of Barton County, located in central Kansas, in the Central Palmyra is a village in Otoe County, Nebraska, United States. 
Though tornadoes can strike in an instant, there are precautions and preventative measures that people can take to increase the chances of surviving a tornado. Authorities such as the Storm Prediction Center advise having a tornado plan. The Storm Prediction Center (SPC located in Norman, Oklahoma, is part of the National Centers for Environmental Prediction (NCEP operating under When a tornado warning is issued, going to a basement or an interior first-floor room of a sturdy building greatly increases chances of survival.  In tornado-prone areas, many buildings have storm cellars on the property. Storm cellars are underground structures that are either located below buildings or are built underground near houses or other such buildings These underground refuges have saved thousands of lives. 
Some countries have meteorological agencies which distribute tornado forecasts and increase levels of alert of a possible tornado (such as tornado watches and warnings in the United States and Canada). See Severe weather terminology for a comprehensive article on related weather terms A tornado warning is an alert issued by government weather services to warn an area that a Tornado may be Imminent. Weather radios provide an alarm when a severe weather advisory is issued for the local area, though these are mainly available only in the United States. A weather radio service is a broadcast service which airs special weather-related emergency broadcasts and announcements
Unless the tornado is far away and highly visible, meteorologists advise that drivers park their vehicles far to the side of the road (so as not to block emergency traffic), and find a sturdy shelter. If no sturdy shelter is nearby, getting low in a ditch is the next best option. Highway overpasses are extremely bad shelter during tornadoes (see next section). 
One of the most persistent myths associated with tornadoes is that opening windows will lessen the damage caused by the tornado. Tornado myths are common misconceptions and Urban legends related to Tornadoes They often deal with tornado safety the minimization of tornado damage and false assumptions While there is a large drop in atmospheric pressure inside a strong tornado, it is unlikely that the pressure drop would be enough to cause the house to explode. Some research indicates that opening windows may actually increase the severity of the tornado's damage. Regardless of the validity of the explosion claim, time would be better spent seeking shelter before a tornado than opening windows. A violent tornado can destroy a house whether its windows are open or closed. 
Another commonly held belief is that highway overpasses provide adequate shelter from tornadoes. On the contrary, a highway overpass is a dangerous place during a tornado. In the 1999 Oklahoma tornado outbreak of May 3, 1999, three highway overpasses were directly struck by tornadoes, and at all three locations there was a fatality, along with many life-threatening injuries. The 1999 Oklahoma tornado outbreak was a Severe weather event that lasted from May 3 until May 6, 1999 and brought violent storms to Oklahoma Events 1491 - Kongo monarch Nkuwu Nzinga is baptised by Portuguese missionaries adopting the baptismal name of João Year 1999 ( MCMXCIX) was a Common year starting on Friday (link will display full 1999 Gregorian calendar) The small area under the overpasses created a kind of wind tunnel, increasing the wind's speed, making matters worse. A wind tunnel is a research tool developed to assist with studying the effects of air moving over or around solid objects  By comparison, during the same tornado outbreak, more than 2000 homes were completely destroyed, with another 7000 damaged, and yet only a few dozen people died in their homes. 
An old belief is that the southwest corner of a basement provides the most protection during a tornado. The safest place is the side or corner of an underground room opposite the tornado's direction of approach (usually the northeast corner), or the central-most room on the lowest floor. Taking shelter under a sturdy table, in a basement, or under a staircase increases chances of survival even more. 
Finally, there are areas which people believe to be protected from tornadoes, whether by a major river, a hill or mountain, or even protected by "spirits". The English word " spirit " comes from the Latin " spiritus " (breath Tornadoes have been known to cross major rivers, climb mountains, and affect valleys. As a general rule, no area is "safe" from tornadoes, though some areas are more susceptible than others.  (See Tornado climatology). Tornado climatology is the study of where and when Tornadoes occur as well as associated physical reasons for this distribution
Meteorology is a relatively young science and the study of tornadoes even more so. Although studied for about 140 years and intensively for around 60 years, there are still aspects of tornadoes which remain a mystery.  Scientists do have a fairly good idea of the development of thunderstorms and mesocyclones, and the meteorological conditions conducive to their formation; however, the step from supercell (or other respective formative processes) to tornadogenesis and predicting tornadic vs. A mesocyclone is a Vortex of air approximately 2 to 10 km in diameter (the Mesoscale of meteorology within a convective Storm A supercell is a severe thunderstorm with a deep continuously rotating updraft (a Mesocyclone) Tornadogenesis is the process by which a Tornado forms There are many types of tornadoes and each type of tornado can have several different methods of formation non-tornadic mesocyclones is not yet well understood and is the focus of much research.
Also under study are the low-level mesocyclone and the stretching of low-level vorticity which tightens into a tornado, namely, what are the processes and what is the relationship of the environment and the convective storm. Vorticity is a mathematical concept used in Fluid dynamics. It can be related to the amount of " circulation " or "rotation" (or more strictly the Intense tornadoes have been observed forming simultaneously with a mesocyclone aloft (rather than succeeding mesocyclogenesis) and some intense tornadoes have occurred without a mid-level mesocyclone. In particular, the role of downdrafts, particularly the rear-flank downdraft, and the role of baroclinic boundaries, are intense areas of study. An updraft or downdraft ( air pocket) is the vertical movement of Air as a Weather related phenomenon The rear flank downdraft or RFD is a region of dry air wrapping around the back of a Mesocyclone in a Supercell thunderstorm In Fluid dynamics, the baroclinity (sometimes called baroclinicity) is a measure of the Stratification in a fluid
Reliably predicting tornado intensity and longevity remains a problem, as do details affecting characteristics of a tornado during its life cycle and tornadolysis. Other rich areas of research are tornadoes associated with mesovortices within linear thunderstorm structures and within tropical cyclones. 
Scientists still do not know the exact mechanisms by which most tornadoes form, and occasional tornadoes still strike without a tornado warning being issued, especially in under-developed countries. Analysis of observations including both stationary and mobile (surface and aerial) in-situ and remote sensing (passive and active) instruments generates new ideas and refines existing notions. In situ (ɪn siːˈtuː is a Latin phrase meaning in the place. Remote sensing is the small or large-scale acquisition of information of an object or phenomenon by the use of either recording or real-time sensing device(s that is not in physical Numerical modeling also provides new insights as observations and new discoveries are integrated into our physical understanding and then tested in computer simulations which validate new notions as well as produce entirely new theoretical findings, many of which are otherwise unattainable. Note The term model has a different meaning in Model theory, a branch of Mathematical logic. A computer simulation, a computer model or a computational model is a Computer program, or network of computers that attempts to simulate an Importantly, development of new observation technologies and installation of finer spatial and temporal resolution observation networks have aided increased understanding and better predictions.
Research programs, including field projects such as VORTEX, deployment of TOTO (the TOtable Tornado Observatory), Doppler On Wheels (DOW), and dozens of other programs, hope to solve many questions that still plague meteorologists. V erification of the O rigins of R otation in T ornadoes Ex periment or VORTEX, is a field project that seeks to understand how a The TOtable Tornado Observatory (nicknamed "TOTO" after the dog in the movie The Wizard of Oz) is a large instrumented metal barrel which scientists attempted to put Doppler On Wheels (or DOW is a project maintained by the Center for Severe Weather Research led by Joshua Wurman, with the funding mainly provided by the  Universities, government agencies such as the National Severe Storms Laboratory, private-sector meteorologists, and the National Center for Atmospheric Research are some of the organizations very active in research; with various sources of funding, both private and public, a chief entity being the National Science Foundation. The National Severe Storms Laboratory (or NSSL) is a National Oceanic and Atmospheric Administration weather research laboratory located at the National Weather The National Center for Atmospheric Research ( NCAR) is a non-governmental U The National Science Foundation (NSF is a United States Government agency that supports fundamental Research and Education in all the non-medical
The National Severe Storms Laboratory (or NSSL) is a National Oceanic and Atmospheric Administration weather research laboratory located at the National Weather The National Geographic Magazine is the official journal of the National Geographic Society.