A tornado in central Oklahoma. The tornado itself is the thin tube reaching from the cloud to the ground. The lower part of this tornado is surrounded by a translucent dust cloud, kicked up by the tornado's strong winds at the surface

A tornado is a violently rotating column of air which is in contact with both a cumulonimbus cloud or, in rare cases, a cumulus cloud base and the surface of the earth. 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. Look up tornado in Wiktionary, the free dictionary. ... Image File history File links Download high-resolution version (1024x679, 59 KB) One of several tornadoes observed by the VORTEX-99 team on May 3, 1999, in central Oklahoma. ... Image File history File links Download high-resolution version (1024x679, 59 KB) One of several tornadoes observed by the VORTEX-99 team on May 3, 1999, in central Oklahoma. ... For other uses, see Oklahoma (disambiguation). ... Transparent glass ball In optics, transparency is the property of allowing light to pass. ... Cumulonimbus (Cb) is a type of cloud that is tall, dense, and involved in thunderstorms and other intense weather. ... This article or section does not adequately cite its references or sources. ... For other uses, see Condensation (disambiguation). ... A typical kitchen funnel. ... Debris (French, pronounced (IPA) dibri) 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. 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).^[1][2][3] Miles per hour is a unit of speed, expressing the number of international miles covered per hour. ... Kilometres per hour (American spelling: kilometers per hour) is a unit of both speed (scalar) and velocity (vector). ... A foot (plural: feet or foot;[1] symbol or abbreviation: ft or, sometimes, ′ – a prime) is a unit of length, in a number of different systems, including English units, Imperial units, and United States customary units. ... This article is about the unit of length. ... “Miles” redirects here. ... “km” redirects here. ...

Although tornadoes have been observed on every continent except Antarctica, most occur in the United States.^[4] 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.^[5] For other uses, see Asia (disambiguation). ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ... Categories: Africa geography stubs | Southern Africa ... For other uses, see Europe (disambiguation). ...

Definitions

A tornado near Seymour, Texas.

Tornado

A tornado is defined by the Glossary of Meteorology as "a violently rotating column of air, in contact with the ground, either pendant from a cumuliform cloud or underneath a cumuliform cloud, and often (but not always) visible as a funnel cloud..."^[6] In practice, for a vortex to be classified as a tornado, it must be in contact with both the ground and the cloud base. Scientists have not yet created a complete definition of the word; for example, there is disagreement as to whether separate touchdowns of the same funnel constitute separate tornadoes.^[3]

Condensation funnel

A tornado is not necessarily visible; however, the intense low pressure caused by the high wind speeds (see Bernoulli's principle) and rapid rotation (due to cyclostrophic balance) usually causes water vapor in the air to condense into a visible condensation funnel.^[4] The tornado is the vortex of wind, not the condensation cloud.

A funnel cloud is a visible condensation funnel with no associated strong winds at the surface. Not all funnel clouds evolve into a tornado. However, many tornadoes are preceded by a funnel cloud. Most tornadoes produce strong winds at the surface while the visible funnel is still above the ground, so it is difficult to discern the difference between a funnel cloud and a tornado from a distance.^[3]

Tornado family

Occasionally, a single storm will produce more than one tornado, either simultaneously or in succession. Multiple tornadoes produced by the same storm are referred to as a tornado family. ^[7]

Tornado outbreak

Occasionally, several tornadoes are spawned from the same large-scale storm system. If there is no break in activity, this is considered a tornado outbreak, although there are various definitions. A period of several successive days with tornado outbreaks in the same general area (spawned by multiple weather systems) is a tornado outbreak sequence, occasionally called an extended tornado outbreak.^[6][8][9]

Image File history File links Seymour_Texas_Tornado. ... Image File history File links Seymour_Texas_Tornado. ... Seymour is the county seat and only town in Baylor County, Texas, United StatesGR6. ... A cumulus cloud (Cu) is a cloud belonging to a class characterized by puffs, mounds or towers, with flat bases and tops that often resemble cauliflower. ... A funnel cloud. ... Bernoullis Principle states that for an ideal fluid (low speed air is a good approximation), with no work being performed on the fluid, an increase in velocity occurs simultaneously with decrease in pressure or a change in the fluids gravitational potential energy. ... In Atmospheric Science, Balanced Flow is an idealization of atmospheric motion in which flow is considered steady-state. ... Water vapor or water vapour (see spelling differences), also aqueous vapor, is the gas phase of water. ... Vortex created by the passage of an aircraft wing, revealed by coloured smoke A vortex (pl. ... For other uses, see Wind (disambiguation). ... For other uses, see Cloud (disambiguation). ... A funnel cloud. ... Often mistaken for single long track tornadoes, Tornado families are a series of tornadoes which occur along a similar path. ... 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. ... A tornado outbreak sequence (or extended tornado outbreak) is a period of continuous or near-continuous high tornado activity consisting of a series of tornado outbreaks. ...

Etymology

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". 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.^[10][11] Tornadoes are also commonly referred to as twisters.^[12] Latin was the language originally spoken in the region around Rome called Latium. ... For other uses, see Thunder (disambiguation). ... Folk etymology is a term used in two distinct ways: A commonly held misunderstanding of the origin of a particular word, a false etymology. ...

Types

A multiple-vortex tornado outside of Dallas, Texas on April 2, 1957.

Image File history File links 1957_Dallas_multi-vortex_1_edited. ... Image File history File links 1957_Dallas_multi-vortex_1_edited. ... Dallas redirects here. ... is the 92nd day of the year (93rd in leap years) in the Gregorian calendar. ... Year 1957 (MCMLVII) was a common year starting on Tuesday (link displays the 1957 Gregorian calendar). ...

True tornadoes

Multiple vortex tornado

A multiple vortex tornado is a type of tornado in which two or more columns of spinning air rotate around a common center. Multivortex structure can occur in almost any circulation, but is very often observed in intense tornadoes.

Satellite tornado

A satellite tornado is a term for a weaker tornado which forms very near a large, strong tornado contained within the same mesocyclone. The satellite tornado may appear to "orbit" the larger tornado (hence the name), giving the appearance of one, large multi-vortex tornado. However, a satellite tornado is a distinct funnel, and is much smaller than the main funnel.^[3]

A waterspout near the Florida Keys.

Waterspout

A waterspout is officially defined by the US National Weather Service simply as a tornado over water. However, researchers typically distinguish "fair weather" waterspouts from tornadic waterspouts.

• Fair weather waterspouts are less severe but far more common, and are similar in dynamics to dust devils and landspouts.^[13] They form at the bases of cumulus congestus cloud towers in tropical and semitropical waters.^[13] They have relatively weak winds, smooth laminar walls, and typically travel very slowly, if at all.^[13] They occur most commonly in the Florida Keys.^[14]
• Tornadic waterspouts are more literally "tornadoes over water". They can form over water like mesocyclonic tornadoes, or be a land tornado which crosses onto water. Since they form from severe thunderstorms and can be far more intense, faster, and longer-lived than fair weather waterspouts, they are considered far more dangerous.

A landspout near North Platte, Nebraska on May 22, 2004.

Landspout

Landspout is an unofficial term for a tornado not associated with a mesocyclone. The name stems from their characterization as essentially a "fair weather waterspout on land". Waterspouts and landspouts share many defining characteristics, including relative weakness, short lifespan, and a small, smooth condensation funnel which often does not reach the ground. Landspouts also create a distinctively laminar cloud of dust when they make contact with the ground, due to their differing mechanics from true mesoform tornadoes. Though usually weaker than classic tornadoes, they still produce strong winds and may cause serious damage.^[3][15]

A multiple vortex tornado is a tornado that contains several vortices rotating around and inside of and part of the main vortex. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... Image File history File links Trombe. ... Image File history File links Trombe. ... Palm trees in Islamorada The Florida Keys is an archipelago of about 1700 islands in the southeast United States. ... Waterspouts on the beach of Kijkduin near The Hague, the Netherlands on 2006 August 27. ... The National Weather Service (NWS) is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration (NOAA) of the United States government. ... Dust Devil Johnsonville, South Carolina A dust devil is a rotating updraft, 1000 meters or more high and tens of meters in diameter. ... A landspout is a tornado not associated with the mesocyclone of a thunderstorm. ... Cumulus congestus clouds are characteristic of unstable areas of the atmosphere which are undergoing convection. ... Laminar flow (bottom) and turbulent flow (top) over a submarine hull. ... Palm trees in Islamorada The Florida Keys is an archipelago of about 1700 islands in the southeast United States. ... It has been suggested that this article or section be merged into Supercell. ... A severe thunderstorm is a thunderstorm with winds 58 mph or greater, 3/4 inch or larger hail, or tornadoes. ... Image File history File links GID_Landspout. ... Image File history File links GID_Landspout. ... Grain elevator along the Union Pacific Railroad in downtown North Platte North Platte is a city in Lincoln County in southwestern Nebraska on I-80 where the South Platte River and the North Platte River join to form the Platte River. ... is the 142nd day of the year (143rd in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... A landspout is a tornado not associated with the mesocyclone of a thunderstorm. ... It has been suggested that this article or section be merged into Supercell. ... laminar and turbulent water flow over the hull of a submarine In fluid dynamics, laminar flow is a flow regime characterized by high momentum diffusion, low momentum convection, and pressure and velocity independence from time. ...

Tornado-like circulations

Gustnado

A gustnado (gust front tornado) is a small, vertical swirl associated with a gust front or downburst. Because they are technically not associated with the cloud base, there is some debate as to whether or not gustnadoes are actually tornadoes. They are formed when fast moving cold, dry outflow air from a thunderstorm is blown through a mass of stationary, warm, moist air near the outflow boundary, resulting in a "rolling" effect (often exemplified through a roll cloud). If low level wind shear is strong enough, the rotation can be turned horizontally (or diagonally) and make contact with the ground. The result is a gustnado.^[3][16] They usually cause small areas of heavier rotational wind damage among areas of straight-line wind damage. It is also worth noting that since they are absent of any Coriolis influence from a mesocyclone, they seem to be alternately cyclonic and anticyclonic without preference.

Dust devil in Johnsonville, South Carolina.

Dust devil

A dust devil resembles a tornado in that it is a vertical swirling column of air. However, they form under clear skies and are rarely as strong as even the weakest tornadoes. They form when a strong convective updraft is formed near the ground on a hot day. If there is enough low level wind shear, the column of hot, rising air can develop a small cyclonic motion that can be seen near the ground. They are not considered tornadoes because they form during fair weather and are not associated with any actual cloud. However, they can, on occasion, result in major damage, especially in arid areas.^[17][18]

Winter Waterspout

A winter waterspout, also known as a snow devil, an icespout, an ice devil or a snowspout, is an extremely rare meteorological phenomenon in which a vortex resembling that of a waterspout forms under the base of a snow squall.

Fire whirl

Tornado-like circulations occasionally occur near large, intense wildfires and are called fire whirls. They are not considered tornadoes except in the rare case where they connect to a pyrocumulus or other cumuliform cloud above. Fire whirls usually are not as strong as tornadoes associated with thunderstorms. However, they can produce significant damage.^[8]

Steam devil

A steam devil is a term describing a rotating updraft that involves steam or smoke. A steam devil is very rare, but they mainly form from smoke emitting from a power plant smokestack. Hot springs and deserts may also be suitable locations for a steam devil to form.

Cold air vortex

A cold air vortex or shear funnel is a tiny, harmless funnel cloud which occasionally forms underneath or on the sides of normal cumuliform clouds, rarely causing any winds at ground-level.^[19] Their genesis and mechanics are poorly understood, as they are quite rare, short lived, and hard to spot (due to their non-rotational nature and small size).

A Gustnado is a type of short-lived cyclonic circulation that can form with severe thunderstorms. ... An outflow boundary is a storm-scale or mesoscale boundary separating thunderstorm-cooled air (outflow) from the surrounding air; similar in effect to a cold front, with passage marked by a wind shift and usually a drop in temperature. ... The curl phase soon after an intense microburst impacted the surface Downburst damages in a straight line. ... A shelf cloud associated with a heavy or severe thunderstorm over Enschede, The Netherlands. ... A roll cloud is a low, horizontal tube-shaped arcus cloud associated with a thunderstorm gust front (or sometimes with a cold front). ... This article is about the meteorological phenomenon. ... In meteorology, an anticyclone is a weather phenomenon associated with atmospheric high pressure. ... Dust Devil Image copyleft: Image taken by me, released under GFDL Pollinator 05:53, Sep 19, 2004 (UTC) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Dust Devil Image copyleft: Image taken by me, released under GFDL Pollinator 05:53, Sep 19, 2004 (UTC) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Johnsonville is a city located in Florence County, South Carolina. ... A dust devil in the Mojave Desert. ... For the Marvel Comics character, see Windshear (comics). ... In general terms, the climate of a locale or region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life. ... A winter waterspout seen over Lake Ontario from Whitby Ontario, January 26, 1994 A winter waterspout, also known as a snow devil or a snowspout, is an extremely rare meteorological phenomenon in which a vortex resembling that of a waterspout forms under the base of a snow squall. ... For other uses, see Wildfire (disambiguation). ... A fire whirl with flames in the vortex. ... Pyrocumulus, or fire cumulus, is a dense cumuliform cloud usually found at an altitude of 1500 m. ... This article is about rotation as a movement of a physical body. ... An Updraft or Downdraft is refers to the vertical movement of air as a weather related phenomenom. ... For other uses, see Steam (disambiguation). ... This article does not cite any references or sources. ... A power station (also power plant) is a facility for the generation of electric power. ... Chimney stacks on a Newcastle upon Tyne building A chimney is a system for venting hot gases and smoke from a stove, furnace or fireplace to the outside atmosphere. ... Green Dragon Spring at Norris Geyser A hot spring is a place where warm or hot groundwater issues from the ground on a regular basis for at least a predictable part of the year, and is significantly above the ambient ground temperature (which is usually around 55~57°F or... A dune in the Egyptian desert In geography, a desert is a landscape form or region that receives little precipitation. ... A funnel cloud. ...

Characteristics

A wedge tornado, nearly a mile wide. This tornado hit Binger, Oklahoma.

A rope tornado in its dissipating stage.

Image File history File links Binger_Oklahoma_Tornado. ... Image File history File links Binger_Oklahoma_Tornado. ... Binger is a town located in Caddo County, Oklahoma. ... Image File history File links Download high resolution version (700x911, 57 KB) Summary A roping tornado, in the last stages of its life. ... Image File history File links Download high resolution version (700x911, 57 KB) Summary A roping tornado, in the last stages of its life. ...

Shape

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. However, tornadoes can appear in many shapes and sizes. A typical kitchen funnel. ... For other uses, see Cloud (disambiguation). ... Debris (French, pronounced (IPA) dibri) is a word used to describe the remains of something that has been otherwise destroyed. ...

Small, relatively weak landspouts may only be visible as a small swirl of dust on the ground. 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.^[15] 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. 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.^[20] A landspout is a tornado not associated with the mesocyclone of a thunderstorm. ... For other uses, see Wedge (disambiguation). ...

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.^[21]

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.^[17]

Size

In the United States, on average tornadoes are around 500 feet (150 m) across, and stay on the ground for 5 miles (8 km).^[17] 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.^[17] 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 2.5 miles (4 km) wide at the ground.^[2] is the 142nd day of the year (143rd in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ...

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). 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.^[8] In fact, modern reanalysis of the path suggests that the tornado began 15 miles (24 km) further west than previously thought.^[22] 1Time from first tornado to last tornado 2Most severe tornado damage; see Fujita Scale The Great Tri-State Tornado of Wednesday, March 18, 1925, crossed from southeastern Missouri, through southern Illinois, then into southwestern Indiana, and was the deadliest tornado in U.S. history. ... This article is about the U.S. state. ... Official language(s) English[1] Capital Springfield Largest city Chicago Largest metro area Chicago Metropolitan Area Area  Ranked 25th  - Total 57,918 sq mi (140,998 km²)  - Width 210 miles (340 km)  - Length 390 miles (629 km)  - % water 4. ... For other uses, see Indiana (disambiguation). ... is the 77th day of the year (78th in leap years) in the Gregorian calendar. ... Year 1925 (MCMXXV) was a common year starting on Thursday (link will display the full calendar) of the Gregorian calendar. ...

Appearance

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.^[17] For other uses, see Great Plains (disambiguation). ...

Photographs of the Waurika, Oklahoma tornado of May 30, 1976, taken at nearly the same time by two photographers. In the top picture, the tornado is front-lit, with the sun behind the east-facing camera, so the funnel appears nearly white. In the lower image, where the camera is facing the opposite direction, the tornado is back-lit, with the sun behind the clouds.^[23]

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. 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.^[24][12] Image File history File linksMetadata Download high resolution version (498x636, 30 KB)Montage of Waurika_Oklahoma_Tornado_Front-Lit. ... Image File history File linksMetadata Download high resolution version (498x636, 30 KB)Montage of Waurika_Oklahoma_Tornado_Front-Lit. ... Waurika is a city located in Jefferson County, Oklahoma. ... is the 150th day of the year (151st in leap years) in the Gregorian calendar. ... Year 1976 Pick up sticks(MCMLXXVI) was a leap year starting on Thursday (link will display full calendar) of the Gregorian calendar. ... For other uses, see Camera (disambiguation). ... Martha Byrne from As the World Turns, exhibiting the effects of back lighting on ones hair. ...

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. 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.^[8] Also, night-time tornadoes are often illuminated by frequent lightning. Weather radar in Norman, Oklahoma with rainshaft (Source: NOAA) Environment Canada King City (CWKR) weather radar station. ...

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. 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.^[25][26][27] A Doppler On Wheels unit observing a tornado near Attica, Kansas. ... Eye of the storm redirects here. ... Cyclone Catarina, a rare South Atlantic tropical cyclone viewed from the International Space Station on March 26, 2004 Hurricane and Typhoon redirect here. ...

Rotation

Tornadoes normally rotate cyclonically in direction (counterclockwise in the northern hemisphere, clockwise in the southern). 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. Supercells and tornadoes rotate cyclonically in numerical simulations even when the Coriolis effect is neglected.^[28][29] Low-level mesocyclones and tornadoes owe their rotation to complex processes within the supercell and ambient environment.^[30] This article is about the meteorological phenomenon. ... Northern hemisphere highlighted in yellow. ... southern hemisphere highlighted in yellow (Antarctica not depicted). ... In the inertial frame of reference (upper part of the picture), the black object moves in a straight line. ... The Rossby number, named for Carl-Gustav Arvid Rossby, is a dimensionless number used in describing fluid flow, usually in geophysical phenomena in the oceans and atmosphere. ... It has been suggested that this article or section be merged into Supercell. ...

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.^[31] 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.^[32] A classic hook echo, indicating the presence of a rear flank downdraft (and in this case, a tornado). ... An anticyclonic tornado is a tornado which rotates in a clockwise direction in the Northern Hemisphere and a counterclockwise direction in the Southern Hemisphere. ...

Sound and seismology

Tornadoes emit widely on the acoustics spectrum and the sounds are cased by multiple mechanisms. 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. Many tornadoes are not audible from much distance; the nature and propagation distance of the audible sound depends on atmospheric conditions and topography. Acoustics is the branch of physics concerned with the study of sound (mechanical waves in gases, liquids, and solids). ... An audio frequency (abbreviation: AF) is any frequency from about 20 hertz to about 20 kilohertz, which is the approximate range of sound frequencies that is audible to humans. ... For other uses, see Train (disambiguation). ... For other uses, see Waterfall (disambiguation). ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ...

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. 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”.^[33] Turbulent flow around an obstacle; the flow further away is laminar Laminar and turbulent water flow over the hull of a submarine Turbulence creating a vortex on an airplane wing In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by low-momentum diffusion, high momentum convection, and... In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid flows past an obstacle. ... For other uses, see Western honey bee and Bee (disambiguation). ...

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.^[34]

An illustration of generation of infrasound in tornadoes by the Earth System Research Laboratory's Infrasound Program.

Tornadoes also produce identifiable inaudible infrasonic signatures.^[35] 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.^[36] Tornadoes also produce a detectable seismic signature, and research continues on isolating it and understanding the process.^[37] Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The Earth System Research Laboratory (ESRL) is a laboratory in National Oceanic and Atmospheric Administration (NOAA)/Office of Oceanic and Atmospheric Research (OAR). ... Infrasound is sound with a frequency too low to be detected by the human ear (less than approximately 20 hertz). ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the movement of waves through the Earth. ...

Electromagnetic, lightning, and other effects

Tornadoes emit on the electromagnetic spectrum, for example, with sferics and E-field effects detected.^[36][38] The effects vary, mostly with little observed consistency. Although some radiations are marked as N for no in the diagram, some waves do in fact penetrate the atmosphere, although extremely minimally compared to the other radiations The electromagnetic (EM) spectrum is the range of all possible electromagnetic radiation. ... A frequency vs. ... In physics, an electric field or E-field is an effect produced by an electric charge that exerts a force on charged objects in its vicinity. ...

Correlations with patterns of lightning activity have also been observed, but little in way of consistent correlations have been advanced. 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.^[39] 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. Not to be confused with lighting. ... Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. ... Thermodynamics (Greek: thermos = heat and dynamic = change) is the physics of energy, heat, work, entropy and the spontaneity of processes. ...

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. This article does not cite any references or sources. ...

In addition to winds, tornadoes also exhibit changes in atmospheric variables such as temperature, moisture, and pressure. For example, on June 24, 2003 near Manchester, South Dakota, a probe measured a 100 mbar (hPa) (2.95 inHg) pressure deficit. The pressure dropped gradually as the vortex approached then dropped extremely rapidly to 850 mbar (hPa) (25.10 inHg) in the core of the violent tornado before rising rapidly as the vortex moved away, resulting in a V-shape pressure trace. Temperature tends to decrease and moisture content to increase in the immediate vicinity of a tornado.^[40] For other uses, see Temperature (disambiguation). ... Dew on a spider web Moldy bread Moisture generally refers to the presence of water, often in trace amounts. ... Atmospheric pressure is the pressure at any given point in the Earths atmosphere. ... is the 175th day of the year (176th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... Manchester, South Dakota was a small town located in South Dakota. ... The bar (symbol bar), decibar (symbol dbar) and the millibar (symbol mbar, also mb) are units of pressure. ... For other uses, see Pascal. ... Pressure is the application of force to a surface, and the concentration of that force in a given area. ... The bar (symbol bar), decibar (symbol dbar) and the millibar (symbol mbar, also mb) are units of pressure. ... For other uses, see Pascal. ... Pressure is the application of force to a surface, and the concentration of that force in a given area. ...

Life cycle

A sequence of images showing the birth of a tornado. First, the rotating cloud base lowers. This lowering becomes a funnel, which continues descending while winds build near the surface, kicking up dust and other debris. Finally, the visible funnel extends to the ground, and the tornado begins causing major damage. This tornado, near Dimmitt, Texas, was one of the best-observed violent tornadoes in history.

Further information: Tornadogenesis

Image File history File links Download high resolution version (700x1389, 75 KB) Summary This sequence of three photographs was taken by a member of the VORTEX project outside of Dimmit, TX on June 2, 1995. ... Image File history File links Download high resolution version (700x1389, 75 KB) Summary This sequence of three photographs was taken by a member of the VORTEX project outside of Dimmit, TX on June 2, 1995. ... Dimmitt is a city located in Castro County, Texas. ... A sequence of images showing the birth of a supercellular tornado. ...

Supercell relationship

See also: Supercell

Tornadoes often develop from a class of thunderstorms known as supercells. Supercells contain mesocyclones, an area of organized rotation a few miles up in the atmosphere, usually 1–6 miles (2–10 km) across. Most intense tornadoes (EF3 to EF5 on the Enhanced Fujita Scale) develop from supercells. In addition to tornadoes, very heavy rain, frequent lightning, strong wind gusts, and hail are common in such storms. Satellite view of a supercell A supercell is a severe thunderstorm with a deep rotating updraft (a mesocyclone) [1]. Supercell thunderstorms are the largest, most severe class of single-cell thunderstorms. ... Satellite view of a supercell A supercell is a severe thunderstorm with a deep rotating updraft (a mesocyclone) [1]. Supercell thunderstorms are the largest, most severe class of single-cell thunderstorms. ... It has been suggested that this article or section be merged into Supercell. ... 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. ...

Most tornadoes from supercells follow a recognizable life cycle.^[15] That begins when increasing rainfall drags with it an area of quickly descending air known as the rear flank downdraft (RFD). This downdraft accelerates as it approaches the ground, and drags the supercell's rotating mesocyclone towards the ground with it. A classic hook echo, indicating the presence of a rear flank downdraft (and in this case, a tornado). ...

Formation

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. As the funnel descends, the rear flank downdraft, also known as 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. A wall cloud with tail cloud A wall cloud is a cloud formation. ...

Maturity

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.

Demise

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.^[23][24][8]

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.^[41]

Intensity and damage

An example of EF1 damage. Here, the roof has been substantially damaged, and the garage door blown outwards, but the walls and supporting structures are still intact.

Main article: Tornado intensity and damage

The Fujita scale and the Enhanced Fujita Scale rate tornadoes by damage caused. 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. 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. 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 (cycloidal marks) may also be analyzed to determine intensity and award a rating. Image File history File links EF1_tornado_damage_example. ... Image File history File links EF1_tornado_damage_example. ... 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. ... A garage door is a large door on a garage or carport that can either be opened manually or by a garage door opener. ... One of the earliest photographs of a tornado. ... F-scale redirects here. ... 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 science, engineering, and research, expert elicitation is the synthesis of opinions of experts of a subject where there is uncertainty due to insufficient data, when such data is unattainable because of physical constraints or lack of resources. ... For other uses, see Skyscraper (disambiguation). ... The TORRO tornado intensity scale (or T-Scale) is a scale measuring tornado intensity between T0 and T10. ... 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). ... Weather radar in Norman, Oklahoma with rainshaft (Source: NOAA) Environment Canada King City (CWKR) weather radar station. ... Photogrammetry is a remote sensing technology 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.^[42] In the case of violent