The following is a glossary of tornado terms. It includes

scientific Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for ...

as well as selected informal terminology.

A

* ''

Advanced Radar Research Center The Advanced Radar Research Center (ARRC) is the largest academic radar program in the United States. The ARRC’s mission is to enhance safety, security, environmental quality, and economic prosperity through interdisciplinary research and the dev ...

'' (ARRC) - * ''

Advection In the field of physics, engineering, and earth sciences, advection is the transport of a substance or quantity by bulk motion of a fluid. The properties of that substance are carried with it. Generally the majority of the advected substance is al ...

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Air parcel In fluid dynamics, within the framework of continuum mechanics, a fluid parcel is a very small amount of fluid, identifiable throughout its dynamic history while moving with the fluid flow. As it moves, the mass of a fluid parcel remains constant, ...

'' - * ''

American Geophysical Union The American Geophysical Union (AGU) is a 501(c)(3) nonprofit organization of Earth, atmospheric, ocean, hydrologic, space, and planetary scientists and enthusiasts that according to their website includes 130,000 people (not members). AGU's ...

'' (AGU) - * ''

American Meteorological Society The American Meteorological Society (AMS) is the premier scientific and professional organization in the United States promoting and disseminating information about the atmospheric, oceanic, and hydrologic sciences. Its mission is to advance th ...

'' (AMS) - * ''Anticipated convection'' (AC) - A convective outlook. * ''

Angular momentum In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational analog of linear momentum. It is an important physical quantity because it is a conserved quantity—the total angular momentum of a closed syst ...

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Anticyclone An anticyclone is a weather phenomenon defined as a large-scale circulation of winds around a central region of high atmospheric pressure, clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere as viewed from ...

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Anticyclonic rotation Anticyclonic rotation, or anticyclonic circulation, is atmospheric motion in the direction opposite to a planet's rotation. For Earth, this motion is in a clockwise direction in the Northern Hemisphere and counterclockwise in the Southern Hemisp ...

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Anticyclonic 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. The term is a naming convention denoting the anomaly from normal rotation which is ...

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Anticyclogenesis Anticyclogenesis is the development or strengthening of an anticyclonic circulation in the atmosphere. It is the opposite of anticyclolysis (the dissolution or weakening of an anticyclone) and has a cyclonic equivalent known as cyclogenesis. Anti ...

'' * '' Arcus cloud'' * ''

Atmospheric pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, ...

'' - Atmosphere

B

* ''

Baroclinity In fluid dynamics, the baroclinity (often called baroclinicity) of a stratified fluid is a measure of how misaligned the gradient of pressure is from the gradient of density in a fluid. In meteorology a baroclinic flow is one in which the densi ...

'' or ''baroclinicity'' - baroclinic * '' Barotropity or ''barotropicity'' - barotropic * Bear's cage - (tornado chaser slang) The precipitation that wraps around a mesocyclone, possibly hiding a tornado on the ground. * ''

Beaufort scale The Beaufort scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale. History The scale was devised in 1805 by the Irish hydrographer Francis Beaufort ...

'' - * ''

Bernoulli's principle In fluid dynamics, Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluid's potential energy. The principle is named after the Swiss mathematici ...

'' - * Blob - Informal term coined by

Erik N. Rasmussen Erik Nels Rasmussen (born January 27, 1957) is an American meteorologist and leading expert on mesoscale meteorology, severe convective storms, forecasting of storms, and tornadogenesis. He was the field coordinator of the first of the VORTEX pro ...

for a descending reflectivity core (DRC). * Boundary - * ''

Bounded weak echo region The bounded weak echo region, also known as a BWER or a vault, is a radar signature within a thunderstorm characterized by a local minimum in radar reflectivity at low levels which extends upward into, and is surrounded by, higher reflectivities a ...

'' (BWER) - * ''

Bow echo A bow echo is the characteristic radar return from a mesoscale convective system that is shaped like an archer's bow. These systems can produce severe straight-line winds and occasionally tornadoes, causing major damage. They can also become de ...

'' - * BRN shear - * '' Bulk Richardson Number'' (BRN) - * Bulk shear - * ''

Buoyancy Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the ...

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C

* ''

Capping inversion A capping inversion is an elevated inversion layer that caps a convective planetary boundary layer. The boundary layer is the part of the atmosphere which is closest to the ground. Normally, the sun heats the ground, which in turn heats th ...

'' (cap) - * ''

Center for Analysis and Prediction of Storms The Center for Analysis and Prediction of Storms (CAPS) was established at the University of Oklahoma in 1989 as one of the first eleven National Science Foundation Science and Technology Centers. Located at the National Weather Center in Norman, ...

'' (CAPS) - * Center for Severe Weather Research (CSWR) - * Chaser convention - Originally it referred to serendipitous meeting of chasers in the field akin to "chaser convergence", but now it mostly refers to th
National Storm Chasers Convention
held annually in the Denver, Colorado area. * Cloud tag - * Cluster outbreak - * Cold air funnel - (colloquialism) * ''

Cold front A cold front is the leading edge of a cooler mass of air at ground level that replaces a warmer mass of air and lies within a pronounced surface trough of low pressure. It often forms behind an extratropical cyclone (to the west in the Northern ...

'' - * Collar cloud - * ''

Colorado low A Colorado low is a low-pressure area that forms in southeastern Colorado or northeastern New Mexico, typically in the winter. After forming, the system moves across the Great Plains. Colorado lows can produce heavy wintry precipitation, and ha ...

'' - * Cool air advection (CAA) - * Condensation funnel - The area of a funnel cloud or tornado where

cloud In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may ...

has condensed. This is not the same thing as a tornado, which is a vortex of wind. * Confluence - * ''

Cooperative Institute for Mesoscale Meteorological Studies The Cooperative Institute for Mesoscale Meteorological Studies is a research organization created in 1978 by a cooperative agreement between the University of Oklahoma (OU) and the National Oceanic and Atmospheric Administration (NOAA). CIMMS p ...

'' (CIMMS) - * ''

Cooperative Institute for Meteorological Satellite Studies __NOTOC__ The Cooperative Institute for Meteorological Satellite Studies (CIMSS) is a research institute where scientists study the use of data from geostationary and polar orbit weather satellites to improve forecasts of weather (including trop ...

'' (CIMSS) - * ''

Cooperative Institute for Precipitation Systems The Cooperative Institute for Precipitation Systems (CIPS) is a collaborative project headed by Saint Louis University to promote understanding of significant precipitation events. It originally focused on the Midwestern United States but expanded ...

'' (CIPS) - * ''

Cooperative Institute for Research in the Atmosphere The Cooperative Institute for Research in the Atmosphere (CIRA) is a scientific research institution at Colorado State University (CSU) that operates under a cooperative agreement with the National Oceanic and Atmospheric Administration (NOAA) Off ...

'' (CIRA) - * ''

Convection Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the c ...

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Convective available potential energy In meteorology, convective available potential energy (commonly abbreviated as CAPE), is the integrated amount of work that the upward (positive) buoyancy force would perform on a given mass of air (called an air parcel) if it rose vertically thro ...

'' (CAPE) - * '' Convective condensation level'' (CCL) - * ''

Convective inhibition Convective inhibition (CIN or CINH) is a numerical measure in meteorology that indicates the amount of energy that will prevent an air parcel from rising from the surface to the level of free convection. CIN is the amount of energy required to o ...

'' (CIN or CINh) - * ''

Convective instability In meteorology, convective instability or stability of an air mass refers to its ability to resist vertical motion. A ''stable'' atmosphere makes vertical movement difficult, and small vertical disturbances dampen out and disappear. In an ''uns ...

'' - * '' Convective outlook'' - * Convective storm - * ''

Convective storm detection Convective storm detection is the meteorological observation, and short-term prediction, of deep moist convection (DMC). DMC describes atmospheric conditions producing single or clusters of large vertical extension clouds ranging from cumulus co ...

'' - * '' Convective storm prediction'' - * ''

Convective temperature The convective temperature (CT or Tc) is the approximate temperature that air near the surface must reach for cloud formation without mechanical lift. In such case, cloud base begins at the convective condensation level (CCL), whilst with mechanica ...

'' (CT or T_c) - * ''

Convergence Convergence may refer to: Arts and media Literature *''Convergence'' (book series), edited by Ruth Nanda Anshen *Convergence (comics), "Convergence" (comics), two separate story lines published by DC Comics: **A four-part crossover storyline that ...

'' - * Core - * Core flow region - * Core punching (or punching the core) - * Corridor outbreak - * ''

Cumulonimbus cloud Cumulonimbus (from Latin ''cumulus'', "heaped" and ''nimbus'', "rainstorm") is a dense, towering vertical cloud, typically forming from water vapor condensing in the lower troposphere that builds upward carried by powerful buoyant air currents. ...

'' (Cb) - * Cycloidal marks - * ''

Cyclonic rotation Cyclonic rotation, or cyclonic circulation, is atmospheric motion in the same direction as a planet's rotation, as opposed to anticyclonic rotation. For Earth, the Coriolis effect causes cyclonic rotation to be in a counterclockwise direction in the ...

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Cyclogenesis Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere (a low-pressure area). Cyclogenesis is an umbrella term for at least three different processes, all of which result in the development of some sort of cycl ...

'' - * ''

Cyclone In meteorology, a cyclone () is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above (opposite to an an ...

'' An area of cyclonic low pressure, from the scale of an extratropical or tropical cyclone to mesolow to a mesocyclone to a tornadocyclone or even to a tornado. - (slang) Historically, used in the US to a tornado.

D

* Damage survey - * DAPPL database - Short for Damage Area Per Path Length, this is one of three US tornado databases and was maintained by

Ted Fujita was a Japanese-American meteorologist whose research primarily focused on severe weather. His research at the University of Chicago on severe thunderstorms, tornadoes, hurricanes, and typhoons revolutionized the knowledge of each. Although ...

at the

University of Chicago The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park neighborhood. The University of Chicago is consistently ranked among the b ...

including tornadoes from 1916 to 1992. * '' Debris cloud'' - * Deepening low - * Deep convection - * Deep shear - * Denver Convergence Vorticity Zone (''DCVZ'') - * ''

Derecho A ''derecho'' (, from es, derecho, link=no , 'straight') is a widespread, long-lived, straight-line wind storm that is associated with a fast-moving group of severe thunderstorms known as a mesoscale convective system. Derechos can cause hurri ...

'' - * '' Descending reflectivity core'' (''DRC'') - * ''

Dew point The dew point is the temperature to which air must be cooled to become saturated with water vapor, assuming constant air pressure and water content. When cooled below the dew point, moisture capacity is reduced and airborne water vapor will ...

'' (''T_d'') - * ''

Dew point depression The dew point depression (T-Td) is the difference between the temperature and dew point temperature at a certain height in the atmosphere. For a constant temperature, the smaller the difference, the more moisture there is, and the higher the r ...

'' - * Dewpoint surge line - * '' Diffluence'' - A pattern of wind flow in which air moves outward (in a "fan-out" pattern) away from a central axis that is oriented parallel to the general direction of the flow. It is the opposite of confluence. * Digging low or digging wave - * Direct hit - * Directional shear - * ''

Divergence In vector calculus, divergence is a vector operator that operates on a vector field, producing a scalar field giving the quantity of the vector field's source at each point. More technically, the divergence represents the volume density of ...

'' - * '' Doppler on Wheels'' (''DOW'') - * '' Doppler weather radar'' - * Dry convection (or dry mixing) - A vertical exchange of air without precipitation at the ground. * ''

Dry line A dry line (also called a dew point line, or Marfa front, after Marfa, Texas) is a line across a continent that separates moist air and dry air. One of the most prominent examples of such a separation occurs in central North America, especially ...

'' (''DL'') - * Dryline bulge - * '' Dry punch'' - * ''

Dry thunderstorm A dry thunderstorm is a thunderstorm that produces thunder and lightning, but where most of its precipitation evaporates before reaching the ground. Dry lightning refers to lightning strikes occurring in this situation. Both are so common in the ...

'' * ''

Dust devil A dust devil is a strong, well-formed, and relatively short-lived whirlwind. Its size ranges from small (half a metre wide and a few metres tall) to large (more than 10 m wide and more than 1 km tall). The primary vertical motion is ...

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Downburst In meteorology, a downburst is a strong downward and outward gushing wind system that emanates from a point source above and blows radially, that is, in straight lines in all directions from the area of impact at surface level. Capable of pro ...

'' - * ''

Downdraft In meteorology, an updraft is a small-scale current of rising air, often within a cloud. Overview Localized regions of warm or cool air will exhibit vertical movement. A mass of warm air will typically be less dense than the surrounding region, ...

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E

* ''

Earth System Research Laboratory The Earth System Research Laboratories (ESRL) is an alliance of four NOAA scientific labs, all located in the David Skaggs Research Center on the Department of Commerce campus in Boulder, Colorado. Organized under NOAA’s Office of Oceanic and ...

'' (ESRL) - * ''

Eddy Eddie or Eddy may refer to: Science and technology *Eddy (fluid dynamics), the swirling of a fluid and the reverse current created when the fluid flows past an obstacle * Eddie (text editor), a text editor originally for BeOS and now ported to Lin ...

'' - * Elevated mixed layer (EML) - * '' Energy-helicity index'' (''EHI'') - * Energy scale (E scale) - Wind speed scales proposed by Nikolai Dotzek for application to

tornado A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, alt ...

es,

downburst In meteorology, a downburst is a strong downward and outward gushing wind system that emanates from a point source above and blows radially, that is, in straight lines in all directions from the area of impact at surface level. Capable of pro ...

tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dep ...

s, other storms and wind in general.Tornado Terms
- Tornado Terminology * ''

Enhanced Fujita scale The Enhanced Fujita scale (abbreviated as EF-Scale) rates tornado intensity based on the severity of the damage they cause. It is used in some countries, including the United States, Canada, China, and Mongolia. The Enhanced Fujita scale repl ...

'' (''EF scale'') - * Enhanced wording - * ''

Entrainment Entrainment may refer to: * Air entrainment, the intentional creation of tiny air bubbles in concrete * Brainwave entrainment, the practice of entraining one's brainwaves to a desired frequency * Entrainment (biomusicology), the synchronization of ...

'' - * ''

Environment and Climate Change Canada Environment and Climate Change Canada (ECCC; french: Environnement et Changement climatique Canada),Environment and Climate Change Canada is the applied title under the Federal Identity Program; the legal title is Department of the Environment ...

'' - * ''

Environmental Modeling Center The Environmental Modeling Center (EMC) is a United States Government agency, which improves numerical weather, marine and climate predictions at the National Centers for Environmental Prediction (NCEP), through a broad program of research in d ...

'' (EMC) - * Environmental Research Laboratories (ERL) - * ''

Environmental Science Services Administration The Environmental Science Services Administration (ESSA) was a United States Federal executive agency created in 1965 as part of a reorganization of the United States Department of Commerce. Its mission was to unify and oversee the meteorologica ...

'' (ESSA) - The predecessor agency (1965-1970) to

NOAA The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...

(1970-present). * ''

Equivalent potential temperature Equivalent potential temperature, commonly referred to as theta-e \left( \theta_e \right), is a quantity that is conserved during changes to an air parcel's pressure (that is, during vertical motions in the Earth's atmosphere, atmosphere), even if w ...

'' (theta-e) - * ''

Extratropical cyclone Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable ...

'' - * '' Eye of a tropical cyclone'' -

F

* Filling low - * ''

Fire whirl A fire whirl or fire devil (sometimes referred to as a fire tornado) is a whirlwind induced by a fire and often (at least partially) composed of flame or ash. These start with a whirl of wind, often made visible by smoke, and may occur when in ...

'' - * '' Forecast Decision Training Branch'' (''FDTB'') - * Forecast Systems Laboratory (''FSL'') - * '' Forward-flank downdraft'' (or ''front-flank downdraft'') (''FFD'') - * '' Fractus cloud'' (Fr) - * '' Front'' - * ''

Frontogenesis Frontogenesis is a meteorological process of tightening of horizontal temperature gradients to produce fronts. In the end, two types of fronts form: cold fronts and warm fronts. A cold front is a narrow line where temperature decreases rapidly. A ...

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Fujita scale The Fujita scale (F-Scale; ), or Fujita–Pearson scale (FPP scale), is a scale for rating tornado intensity, based primarily on the damage tornadoes inflict on human-built structures and vegetation. The official Fujita scale category is deter ...

'' (''F scale'') - * ''

Funnel cloud A funnel cloud is a funnel-shaped cloud of condensed water droplets, associated with a rotating column of wind and extending from the base of a cloud (usually a cumulonimbus or towering cumulus cloud) but not reaching the ground or a water su ...

'' -

G

* Gate-to-gate shear - * ''GMT'' (''

Greenwich Mean Time Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London, counted from midnight. At different times in the past, it has been calculated in different ways, including being calculated from noon; as a c ...

'') - * '' Ground truth'' - * ''

Gust front An outflow boundary, also known as a gust front, 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 ...

'' - * ''

Gustnado A gustnado is a brief, shallow surface-based vortex which forms within the downburst emanating from a thunderstorm. The name is a portmanteau by elision of "gust front tornado", as gustnadoes form due to non-tornadic straight-line wind featur ...

'' -

H

* Handoff - (slang) * '' Helicity'' - * High-precipitation supercell (HP) - * ''

High-pressure area A high-pressure area, high, or anticyclone, is an area near the surface of a planet where the atmospheric pressure is greater than the pressure in the surrounding regions. Highs are middle-scale meteorological features that result from interpl ...

'' (''H'') - * High risk (HIGH) - * ''

Hook echo A hook echo is a pendant or hook-shaped weather radar signature as part of some supercell thunderstorms. It is found in the lower portions of a storm as air and precipitation flow into a mesocyclone, resulting in a curved feature of reflectivit ...

'' - * ''

Horseshoe vortex The horseshoe vortex model is a simplified representation of the vortex system present in the flow of air around a wing. This vortex system is modelled by the ''bound vortex'' (bound to the wing) and two '' trailing vortices'', therefore having ...

'' - * ''

Hurricane A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dep ...

'' -

I

* ''

In situ ''In situ'' (; often not italicized in English) is a Latin phrase that translates literally to "on site" or "in position." It can mean "locally", "on site", "on the premises", or "in place" to describe where an event takes place and is used in ...

'' - * '' Inflow'' - * Inflow jet - * Inflow notch - * Instability - * Intense tornado - A tornado rated F3-F5 or EF3-EF5. * Institute for Disaster Research (IDR) -

J

* Jet max (or jet maximum) - * Jet streak - * ''

Jet stream Jet streams are fast flowing, narrow, meandering air currents in the atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are westerly winds (flowing west to east) ...

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K

* ''

Kinematics Kinematics is a subfield of physics, developed in classical mechanics, that describes the motion of points, bodies (objects), and systems of bodies (groups of objects) without considering the forces that cause them to move. Kinematics, as a fiel ...

'' - * ''

K-index The ''K''-index quantifies disturbances in the horizontal component of earth's magnetic field with an integer in the range 0–9 with 1 being calm and 5 or more indicating a geomagnetic storm. It is derived from the maximum fluctuations ...

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Kelvin–Helmholtz instability The Kelvin–Helmholtz instability (after Lord Kelvin and Hermann von Helmholtz) is a fluid instability that occurs when there is velocity shear in a single continuous fluid or a velocity difference across the interface between two fluids. K ...

'' (''KH waves'') -

L

* ''

Landspout __NOTOC__ Landspout is a term created by atmospheric scientist Howard B. Bluestein in 1985 for a kind of tornado not associated with a mesocyclone. The ''Glossary of Meteorology'' defines a landspout as : "Colloquial expression describing torn ...

'' - * ''

Lapse rate The lapse rate is the rate at which an atmospheric variable, normally temperature in Earth's atmosphere, falls with altitude. ''Lapse rate'' arises from the word ''lapse'', in the sense of a gradual fall. In dry air, the adiabatic lapse rate is ...

'' - * '' Lee trough'' - * ''

Lemon technique The Lemon technique is a method used by meteorologists using weather radar to determine the relative strength of thunderstorm cells in a vertically sheared environment. It is named for Leslie R. Lemon, the co-creator of the current conceptual mode ...

'' - * ''

Level of free convection The level of free convection (LFC) is the altitude in the atmosphere where an air parcel lifted adiabatically until saturation becomes warmer than the environment at the same level, so that positive buoyancy can initiate self-sustained convection. ...

'' (''LFC'') - * ''

Lifted condensation level The lifted condensation level or lifting condensation level (LCL) is formally defined as the height at which the relative humidity (RH) of an air parcel will reach 100% with respect to liquid water when it is cooled by dry adiabatic lifting. The ...

'' (''LCL'') - * ''

Lifted index The lifted index (LI) is the temperature difference between the environment Te(p) and an air parcel lifted adiabatically Tp(p) at a given pressure height in the troposphere (lowest layer where most weather occurs) of the atmosphere, usually 500 h ...

'' (''LI'') - * Lifting mechanism (''lift'') - * ''

Lightning Lightning is a naturally occurring electrostatic discharge during which two electrically charged regions, both in the atmosphere or with one on the ground, temporarily neutralize themselves, causing the instantaneous release of an average ...

'' (''LTG'') - * ''

Line echo wave pattern A line echo wave pattern (LEWP) is a weather radar formation in which a single line of thunderstorms presenting multiple bow echoes forms south (or equatorward) of a mesoscale low-pressure area with a rotating "head". LEWP often are associated w ...

'' (''LEWP'') - * Long track tornado (''LT'') - * Low-precipitation supercell (''LP'') - * ''

Low-pressure area In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather (such as cloudy, windy, with possible ...

'' (''L'') - * '' Low-topped supercell'' (''LT'') -

M

* Maxitornado – * Megasupercell – * Mesoanticyclone – An anticyclonic mesocyclone * ''

Mesoscale meteorology Mesoscale meteorology is the study of weather systems smaller than synoptic scale systems but larger than microscale and storm-scale cumulus systems. Horizontal dimensions generally range from around 5 kilometers to several hundred kilometers. Ex ...

'' – * ''

Mesocyclone A mesocyclone is a meso-gamma mesoscale (or storm scale) region of rotation (vortex), typically around in diameter, most often noticed on radar within thunderstorms. In the northern hemisphere it is usually located in the right rear flank (back ...

'' – * ''

Mesohigh A mesohigh (sometimes called a "bubble high") is a mesoscale high-pressure area that forms beneath thunderstorms. While not always the case, it is usually associated with a mesoscale convective system. In the early stages of research on the subject ...

'' – * ''

Mesolow A squall is a sudden, sharp increase in wind speed lasting minutes, as opposed to a wind gust, which lasts for only seconds. They are usually associated with active weather, such as rain showers, thunderstorms, or heavy snow. Squalls refer to the ...

'' – * ''

Mesonet In meteorology and climatology, a mesonet, portmanteau of mesoscale network, is a network of automated weather and, often, environmental monitoring stations designed to observe mesoscale meteorological phenomena and/or microclimates. Dry lin ...

'' – * ''

Mesoscale convective complex A mesoscale convective complex (MCC) is a unique kind of mesoscale convective system which is defined by characteristics observed in infrared satellite imagery. They are long-lived, often form nocturnally, and commonly contain heavy rainfall, win ...

'' (''MCC'') – * '' Mesoscale convective discussion'' (''MCD'') – * ''

Mesoscale convective system A mesoscale convective system (MCS) is a complex of thunderstorms that becomes organized on a scale larger than the individual thunderstorms but smaller than extratropical cyclones, and normally persists for several hours or more. A mesoscale con ...

'' (''MCS'') – * ''

Mesoscale convective vortex A mesovortex is a small-scale rotational feature found in a convective storm, such as a quasi-linear convective system (QLCS, i.e. squall line), a supercell, or the eyewall of a tropical cyclone. Mesovortices range in diameter from tens of miles to ...

'' (''MCV'') – * ''

'' – * '' Mesovortices'' * ''

Metadata Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the descriptive ...

'' – * ''

METAR METAR is a format for reporting weather information. A METAR weather report is predominantly used by aircraft pilots, and by meteorologists, who use aggregated METAR information to assist in weather forecasting. Raw METAR is the most common fo ...

'' – * '' Microburst'' – * Micronet – A weather observation network even denser than a mesonet, such as the Oklahoma City Micronet. * ''

Microscale meteorology Microscale meteorology or micrometeorology is the study of short-lived atmospheric phenomena smaller than mesoscale, about or less. These two branches of meteorology are sometimes grouped together as "mesoscale and microscale meteorology" (MMM) ...

'' – * Mini-supercell – A distinct kind of supercell that is smaller than a typical supercell. See low topped supercell. * Mini-tornado – A fallacious term often used in European news media to refer to tornadoes occurring there; even large, strong, and/or long track tornadoes produced by supercells. This is apparently due to the erroneous perception that "real" tornadoes do not occur in Europe (or elsewhere where the term is applied). * ''

Misocyclone Tornadogenesis is the process by which a tornado forms. There are many types of tornadoes and these vary in methods of formation. Despite ongoing scientific study and high-profile research projects such as VORTEX, tornadogenesis is a volatile pro ...

'' – * '' Misoscale meteorology'' – * Mixed air and mixed layer – * ''

Mixing ratio In chemistry and physics, the dimensionless mixing ratio is the abundance of one component of a mixture relative to that of all other components. The term can refer either to mole ratio (see concentration) or mass ratio (see stoichiometry). In ...

'' – * Moderate risk (MDT) – * Modified Fujita scale (f scale) – A proposed update in 1992 by

to his original

from 1971 * ''

Moisture Moisture is the presence of a liquid, especially water, often in trace amounts. Small amounts of water may be found, for example, in the air (humidity), in foods, and in some commercial products. Moisture also refers to the amount of water vapo ...

'' – * Moisture convergence (mcon) – * ''

Multicellular thunderstorm A multicellular thunderstorm cluster is a thunderstorm that is composed of multiple cells, each being at a different stage in the life cycle of a thunderstorm. It appears as several anvils clustered together. A cell is an updraft/downdraft couple ...

'' * '' Multiple-vortex tornado'' – * Multivortex mesocyclone (MVMC) –

N

* ''

National Center for Atmospheric Research The US National Center for Atmospheric Research (NCAR ) is a US federally funded research and development center (FFRDC) managed by the nonprofit University Corporation for Atmospheric Research (UCAR) and funded by the National Science Foundatio ...

'' (''NCAR'') - * ''

National Centers for Environmental Prediction The United States National Centers for Environmental Prediction (NCEP) delivers national and global weather, water, climate and space weather guidance, forecasts, warnings and analyses to its Partners and External User Communities. These p ...

'' (''NCEP'') - * ''

National Hurricane Center The National Hurricane Center (NHC) is the division of the United States' NOAA/National Weather Service responsible for tracking and predicting tropical weather systems between the Prime Meridian and the 140th meridian west poleward to the 3 ...

'' (''NHC'') - * National Meteorological Center (''NMC'') - The predecessor to NCEP. * ''

National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditi ...

'' (''NOAA'') - * ''

National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National ...

'' (''NSF'') - * ''

National Severe Storms Forecast Center The Storm Prediction Center (SPC) is a US government agency that is part of the National Centers for Environmental Prediction (NCEP), operating under the control of the National Weather Service (NWS), which in turn is part of the National Oceani ...

'' (''NSSFC'') - A predecessor forecasting center to ''SPC'' that was located in Kansas City, Missouri. * ''

National Severe Storms Laboratory The National Severe Storms Laboratory (NSSL) is a National Oceanic and Atmospheric Administration (NOAA) weather research laboratory under the Office of Oceanic and Atmospheric Research. It is one of seven NOAA Research Laboratories (RLs). NSSL ...

'' (''NSSL'') - A NOAA lab in Norman, Oklahoma tasked with researching severe weather. * National Tornado Database - The official NOAA record of all known tornadoes within the US from 1950 to present. * ''

National Weather Center The National Weather Center (NWC), on the campus of the University of Oklahoma, is a confederation of federal, state, and academic organizations that work together to better understand events that take place in Earth's atmosphere over a wide range ...

'' (''NWC'') - * ''

National Weather Service The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...

'' (''NWS'') - * ''

National Weather Service Training Center The National Weather Service Training Center (NWSTC) provides initial and continuing education to NOAA/ NWS employees in the areas of equipment (operations, maintenance and repair), management, meteorology, hydrology, systems support, and related a ...

'' (''NWSTC'') - * National Wind Institute (''NWI'') - * Negative area - * '' Negatively tilted'' (or ''negative tilt'') -

O

* ''

Occluded front In meteorology, an occluded front is a type of weather front formed during cyclogenesis. The classical and usual view of an occluded front is that it initiates when a cold front overtakes a warm front near a cyclone, such that the warm air is separ ...

'' - * Occlusion - * ''

Overshooting top An overshooting top (or penetrating top) is a dome-like protrusion shooting out of the top of the anvil of a thunderstorm and into the lower stratosphere. When an overshooting top is present for 10 minutes or longer, it is a strong indication that ...

'' - * '' Outflow'' - * ''

Outflow boundary An outflow boundary, also known as a gust front, 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 ...

'' -

P

* '' Particularly Dangerous Situation'' (''PDS'') - * Path length (''Pl'') - The distance a tornado traveled from formation to decay. * Path width (''Pw'') - The diameter of the tornado vortex winds (not the condensation funnel) capable of causing damage. * Pearson scale (or Fujita-Pearson scale) - A tornado rating scale developed by

Allen Pearson Allen Pearson was the Director of the National Severe Storms Forecast Center from 1965 to 1979 and began to collaborate with Tetsuya Theodore "Ted" Fujita on tornado physical characteristics soon after the 1970 Lubbock Tornado. They bounced ideas ...

differentiating path length (P) and path width (P) to accompany NOAA Fujita scale (F) ratings (F-P-P scale). * Pendant - * ''

Phased array radar A phaser is an electronic sound processor used to filter a signal, and it has a series of troughs in its frequency-attenutation graph. The position (in Hz) of the peaks and troughs are typically modulated by an internal low-frequency oscilla ...

'' - * Positive area - * ''

Potential temperature The potential temperature of a parcel of fluid at pressure P is the temperature that the parcel would attain if adiabatically brought to a standard reference pressure P_, usually . The potential temperature is denoted \theta and, for a gas well-ap ...

'' (''

\theta

'') - * ''

Power flash A power flash is a flash of light caused by arcing electrical discharges from damaged electrical equipment, most often severed or arcing Overhead power line, power lines. They are often caused by strong winds, especially those from tropical cyclone ...

'' - A sudden bright light caused when an

overhead power line An overhead power line is a structure used in electric power transmission and distribution to transmit electrical energy across large distances. It consists of one or more uninsulated electrical cables (commonly multiples of three for three-p ...

is severed or especially when a

transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...

explodes. These can be caused by intense winds (or debris) from tornadoes or downbursts, but the most prominent example occurred in New York City during

Hurricane Sandy Hurricane Sandy (unofficially referred to as ''Superstorm Sandy'') was an extremely destructive and strong Atlantic hurricane, as well as the largest Atlantic hurricane on record as measured by diameter, with tropical-storm-force winds spann ...

when its

storm surge A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the ...

flooded a

Con Ed Consolidated Edison, Inc., commonly known as Con Edison (stylized as conEdison) or ConEd, is one of the largest investor-owned energy companies in the United States, with approximately $12 billion in annual revenues as of 2017, and over $62 b ...

power plant. * ''

Precipitable water Precipitable water is the depth of water in a column of the atmosphere, if all the water in that column were precipitated as rain. As a depth, the precipitable water is measured in millimeters or inches. Often abbreviated as "TPW", for Total Preci ...

'' - * Prefrontal trough - * Pressure falls - * ''

Pressure gradient In atmospheric science, the pressure gradient (typically of air but more generally of any fluid) is a physical quantity that describes in which direction and at what rate the pressure increases the most rapidly around a particular location. The p ...

'' - * ''

Pressure gradient force In fluid mechanics, the pressure-gradient force is the force that results when there is a difference in pressure across a surface. In general, a pressure is a force per unit area, across a surface. A difference in pressure across a surface t ...

'' (PGF) - * ''

Pressure system A pressure system is a peak or lull in the sea level pressure distribution. The surface pressure at sea level varies minimally, with the lowest value measured and the highest recorded . High- and low-pressure systems evolve due to interactio ...

'' - * Probe - * PROFS (Prototype Regional Observing and Forecasting Service) - * ''

Pulse-Doppler radar A pulse-Doppler radar is a radar system that determines the range to a target using pulse-timing techniques, and uses the Doppler effect of the returned signal to determine the target object's velocity. It combines the features of pulse radars and ...

'' - * ''

Pulse storm In medicine, a pulse represents the tactile arterial palpation of the cardiac cycle (heartbeat) by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed near the surface of the body, such as at the nec ...

'' -

Q

* ''

Quasi-linear convective system A squall line, or more accurately a quasi-linear convective system (QLCS), is a line of thunderstorms, often forming along or ahead of a cold front. In the early 20th century, the term was used as a synonym for cold front (which often are accompa ...

'' (''QLCS'') -

R

* '' Radar Operations Center'' (ROC) - * ''

Radius of maximum wind The radius of maximum wind (RMW) is the distance between the center of a cyclone and its band of strongest winds. It is a parameter in atmospheric dynamics and tropical cyclone forecasting. The highest rainfall rates occur near the RMW of tropic ...

'' (''RMW'') - * Rain-free base (RFB) - * ''

Rankine vortex The Rankine vortex is a simple mathematical model of a vortex in a viscous fluid. It is named after its discoverer, William John Macquorn Rankine. The vortices observed in nature are usually modelled with an irrotational (potential or free) vort ...

'' - * ''

Rear flank downdraft The rear flank downdraft (RFD) is a region of dry air wrapping around the back of a mesocyclone in a supercell thunderstorm. These areas of descending air are thought to be essential in the production of many supercellular tornadoes. Large hail ...

'' (''RFD'') - * ''

Ridge A ridge or a mountain ridge is a geographical feature consisting of a chain of mountains or hills that form a continuous elevated crest for an extended distance. The sides of the ridge slope away from the narrow top on either side. The line ...

'' - * '' Roll cloud'' - * ''

Remote sensing Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Ear ...

'' - * Rope tornado - * ''

Rossby number The Rossby number (Ro), named for Carl-Gustav Arvid Rossby, is a dimensionless number used in describing fluid flow. The Rossby number is the ratio of inertial force to Coriolis force, terms , \mathbf \cdot \nabla \mathbf, \sim U^2 / L and \Omeg ...

'' - * ''

Rossby wave Rossby waves, also known as planetary waves, are a type of inertial wave naturally occurring in rotating fluids. They were first identified by Sweden-born American meteorologist Carl-Gustaf Arvid Rossby. They are observed in the atmospheres an ...

'' - * Rotation -

S

* ''

Safe room A safe room or panic room is a fortified room that is installed in a private residence or business to provide a safe shelter, or hiding place, for the inhabitants in the event of a break in, home invasion, tornado, terror attack, or other thre ...

'' - * ''

Satellite tornado A satellite tornado is a tornado that revolves around a larger, primary tornado and interacts with the same mesocyclone. Satellite tornadoes occur apart from the primary tornado and are not considered subvortices; the primary tornado and satellit ...

'' - A smaller tornado that orbits a primary tornado associated with the same

mesocyclone A mesocyclone is a meso-gamma mesoscale (or storm scale) region of rotation (vortex), typically around in diameter, most often noticed on radar within thunderstorms. In the northern hemisphere it is usually located in the right rear flank (back ...

. * Scouring - Term used when soil and dirt is pulled from the surface after a tornado. * ''

Scud A Scud missile is one of a series of tactical ballistic missiles developed by the Soviet Union during the Cold War. It was exported widely to both Second and Third World countries. The term comes from the NATO reporting name attached to the m ...

'' (Scattered Cumulus Under Deck) - * Severe local storm (SLS) - A thunderstorm presenting severe characteristics in a localized area. * Severe Local Storms Unit (SELS) - A team of

experts tasked with forecasting

convective Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the ...

weather. It was eventually included as a unit within the NSSFC. * ''

Severe thunderstorm A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are somet ...

'' (svr) - A hazardous thunderstorm capable of causing injury or damage. The U.S. National Weather Service defines a severe thunderstorm as one producing or greater winds, or larger hail, or producing a funnel cloud or tornado. * Shallow convection - Occurs when convective instability exists, but no convection occurs * Shear -

Wind shear Wind shear (or windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizont ...

- Winds aloft, often measured in knots. * Shear funnel - Brief, often weak funnel generated by shear in a thunderstorm. * ''

Shelf cloud An arcus cloud is a low, horizontal cloud formation, usually appearing as an accessory cloud to a cumulonimbus. Roll clouds and shelf clouds are the two main types of arcus clouds. They most frequently form along the leading edge or gust fronts ...

'' - Generally associated with strong thunderstorms, found along the leading edge. Horizontal and dark in appearance. * ''

Shortwave trough A shortwave or shortwave trough is an embedded kink in the trough / ridge pattern. Its length scale is much smaller than that of and is embedded within longwaves, which are responsible for the largest scale (synoptic scale) weather systems. Sho ...

'' - Embedded kink within seen in overall troughing patterns. * Significant tornado - A substantial tornado, one that is rated F2-F5 or EF2-EF5. Grazulis also includes (E)F0-(E)F1 tornadoes that cause a fatality in his definition for The Tornado Project database. * Significant tornado parameter (STP) - Model parameter calculated using Shear values, Instability values, and vorticity values. * '' Skipping tornado'' - Often considered a Multi-vortex tornado. * ''

Skywarn Skywarn (sometimes stylized as SKYWARN) is a program of the National Weather Service (NWS). Its mission is to collect reports of localized severe weather in the United States. These reports are used to aid forecasters in issuing and verifying sev ...

'' - The storm spotting program of the US

. Skywarn organizations have also been formed in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

. The Canadian program is

Canwarn CANWARN, acronym for CANadian Weather Amateur Radio Network, is an organized severe weather spotting and reporting program organized and run by the Meteorological Services Division of Environment Canada. What CANWARN members do is called ground tr ...

. * Slight risk (SLGT) - * ''

Space Science and Engineering Center The Space Science and Engineering Center (SSEC) is a research and development center with primary focus on Earth science research and technology to enhance understanding of the atmosphere of Earth, the other planets in the Solar System, and the c ...

'' (SSEC) - * Speed shear - * Spin-up - A small, ephemeral vortex. These can refer to tornadoes spawned by quasi-linear convective systems or tropical cyclones, which occasionally become strong and fairly long track. A spin-up may sometimes refer to a landspout or gustnado (the latter of which is rarely an actual tornado). * Splitting storm (or storm split) - * '' Stability index'' - * Stacked low - * ''

Steam devil A steam devil is a small, weak whirlwind over water (or sometimes wet land) that has drawn fog into the vortex, thus rendering it visible. They form over large lakes and oceans during cold air outbreaks while the water is still relatively wa ...

'' - * ''

Storm chasing Storm chasing is broadly defined as the deliberate pursuit of any severe weather phenomenon, regardless of motive, but most commonly for curiosity, adventure, scientific investigation, or for news or media coverage. A person who chases stor ...

'' - Traveling with the intent to observe tornadoes and other

severe weather Severe weather is any dangerous meteorological phenomenon with the potential to cause damage, serious social disruption, or loss of human life. Types of severe weather phenomena vary, depending on the latitude, altitude, topography, and atmos ...

. * Storm interaction - * Storm merger - * Storm relative environmental helicity (SREH) or storm relative helicity (SRH) - * '' Storm shelter'' - * ''

Storm spotting Storm spotting is a form of weather spotting in which observers watch for the approach of severe weather, monitor its development and progression, and actively relay their findings to local authorities. History Storm spotting developed in the ...

'' - The observation of severe weather by individuals trained in weather and reporting. Spotters can be stationary or mobile. * '' Storm Data'' (''SD'') - A

National Climatic Data Center The United States National Climatic Data Center (NCDC), previously known as the National Weather Records Center (NWRC), in Asheville, North Carolina, was the world's largest active archive of weather data. Starting as a tabulation unit in New Or ...

(NCDC) publication beginning in 1959 detailing quality controlled tornado and other severe weather summaries as the official

record of such events. * ''

Storm Prediction Center The Storm Prediction Center (SPC) is a US government agency that is part of the National Centers for Environmental Prediction (NCEP), operating under the control of the National Weather Service (NWS), which in turn is part of the National Oceani ...

'' (''SPC'') - The NWS national guidance center that issues tornado, severe thunderstorm (straight-line wind and hail), and wildfire forecasts. * Storm scale - * '' Storm Track (magazine)'' (''ST'') - A science and hobby magazine on storm chasing published from 1977 to 2002. * Stovepipe tornado - (slang) Storm chaser slang for a large cylindrically shaped tornado resembling a stovepipe. * ''

Straight-line wind In meteorology, a downburst is a strong downward and outward gushing wind system that emanates from a point source above and blows Rotational symmetry, radially, that is, in straight lines in all directions from the area of impact at surface l ...

'' - * Streamline - * Streamwise vorticity - * Striations - * Strong tornado - A tornado rated F2-F3, EF2-EF3, T4-T7, or at least as strong as F2, EF2, T4. * Subsidence - * Subvortex - A smaller constituent vortex within a ( multiple vortex) tornado. * Suction spot - Older term for a subvortex. * ''

Supercell A supercell is a thunderstorm characterized by the presence of a mesocyclone: a deep, persistently rotating updraft. Due to this, these storms are sometimes referred to as rotating thunderstorms. Of the four classifications of thunderstorms ( ...

'' (sup) - * Supercell composite parameter (SCP) - * Supertornado - (slang) A colloquial term used to refer to a tornado achieving the maximum of some measurement, such as a F5/EF5 tornado. * ''

Surface weather analysis Surface weather analysis is a special type of weather map that provides a view of weather elements over a geographical area at a specified time based on information from ground-based weather stations. Weather maps are created by plotting or tra ...

'' - * ''

Surface weather observation Surface weather observations are the fundamental data used for safety as well as climatological reasons to forecast weather and issue warnings worldwide. They can be taken manually, by a weather observer, by computer through the use of automate ...

'' - * ''

Synoptic scale meteorology The synoptic scale in meteorology (also known as large scale or cyclonic scale) is a horizontal length scale of the order of 1000 kilometers (about 620 miles) or more. This corresponds to a horizontal scale typical of mid-latitude depressions (e. ...

'' -

T

* Tail - (slang) A colloquial term for a tornado; most commonly used in the Southern U.S. * '' Tail cloud'' - * ''

Temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

'' - * '' Terminal Doppler Weather Radar'' (''TDWR'') - * ''

Thermal A thermal column (or thermal) is a rising mass of buoyant air, a convective current in the atmosphere, that transfers heat energy vertically. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example ...

'' - * ''

Thermodynamics Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws ...

'' - * ''

Thunderstorm A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are some ...

'' (tstm) - * '' The Thunderstorm Project'' - * Thunderstorm spectrum - * ''

Tilted updraft A tilted updraft (also known as a tilted storm) is a thunderstorm which is not vertically erect. This happens as a result of unidirectional wind shear, or a change in wind speed with height. In such an environment, the top of the updraft is push ...

'' * ''

Tornado A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, alt ...

'' (tor) - * ''

Tornado Alley Tornado Alley is a loosely defined area of the central United States where tornadoes are most frequent. The term was first used in 1952 as the title of a research project to study severe weather in areas of Texas, Louisiana, Oklahoma, Kansas, ...

'' - A colloquial term referring to regions where tornadoes are perceived as striking more frequently than other areas. It may also be referred to as a tornado belt, especially when describing smaller areas. * ''

Tornado climatology Tornadoes have been recorded on all continents except Antarctica. They are most common in the middle latitudes where conditions are often favorable for convective storm development. The United States has the most tornadoes of any country, as we ...

'' - The study of geographical and temporal distribution of tornadoes and causes thereof. * Tornado couplet - A primary cyclonic tornado and secondary

anticyclonic 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. The term is a naming convention denoting the anomaly from normal rotation which is ...

pair. * Tornado Debris Project (TDP) - * '' Tornado debris signature'' (TDS) - A more formal term for a debris ball. * ''

Tornado emergency A tornado emergency is an enhanced version of a tornado warning, which is used by the National Weather Service (NWS) in the United States during imminent, significant tornado occurrences in highly populated areas. Although it is not a new warning ...

'' - Enhanced wording used by the U.S. National Weather Service in a

tornado warning A tornado warning ( SAME code: TOR) is a severe weather warning product issued by regional offices of weather forecasting agencies throughout the world to alert the public when a tornado has been reported or indicated by weather radar within the ...

or severe weather statement when a large, intense tornado is expected to impact a highly populated area (traverse a large city or dense suburbs). * ''

Tornado family A tornado family is a series of tornadoes spawned by the same supercell thunderstorm. These families form a line of successive or parallel tornado paths and can cover a short span or a vast distance. Tornado families are sometimes mistaken as a si ...

'' - A series of tornadoes spawned by successive (low-level)

s of the same

supercell A supercell is a thunderstorm characterized by the presence of a mesocyclone: a deep, persistently rotating updraft. Due to this, these storms are sometimes referred to as rotating thunderstorms. Of the four classifications of thunderstorms ( ...

thunderstorm in a process known as cyclic tornadogenesis. Multiple such supercells occurring on the same day in a common region results in a corridor outbreak of tornadoes. * Tornado fog - * Tornado Force scale (TF scale) - * Tornado Intercept Project (TIP) - * ''

Tornado outbreak __NOTOC__ A tornado outbreak is the occurrence of multiple tornadoes spawned by the same synoptic scale weather system. The number of tornadoes required to qualify as an outbreak typically are at least six to ten, with at least two rotational ...

'' - * ''

Tornado outbreak sequence A tornado outbreak sequence, or tornado outbreak day sequence, sometimes referred to as an extended tornado outbreak, is a period of continuous or nearly continuous high tornado activity consisting of a series of tornado outbreaks over multiple da ...

'' - * ''

Tornado preparedness The term "tornado preparedness" refers to safety precautions made before the arrival of and during a tornado. Historically, the steps taken have varied greatly, depending on location, or time remaining before a tornado was expected. For example, i ...

'' - * The Tornado Project (TP) - A concerted research effort from the 1970s-1990s by

Thomas P. Grazulis Thomas P. Grazulis (born August 17, 1942) is an American meteorologist who has written extensively about tornadoes and is head of ''The Tornado Project''. Biography Early career Thomas Grazulis grew up in Worcester, Massachusetts and first c ...

that compiled tornado information for risk assessment. TP published exhaustive accounts, tabulations, and analysis of all known significant tornadoes in the US from 1680 to 1995, which comprises one of three tornado databases. * Tornado pulse - * Tornado rating - A subjective integer value assigned to a tornado differentiating its intensity (or path length or width), typically as a proxy inferred by damage analysis. * Tornado roar - * Tornado scale - * Tornado season - * Tornado stages - * Tornado Symposium - * '' Tornado vortex signature'' (or ''tornadic vortex signature'') (''TVS'') - * ''

Tornado watch A tornado watch ( SAME code: TOA) is a severe weather watch product issued by national weather forecasting agencies when meteorological conditions are favorable for the development of severe thunderstorms capable of producing tornadoes. In addit ...

'' (''TOA'' or ''WT'') - A forecast that atmospheric conditions within a designated area are favorable for significant tornado activity over the next 1–6 hours (colloquially referred to as red box). * ''

Tornado warning A tornado warning ( SAME code: TOR) is a severe weather warning product issued by regional offices of weather forecasting agencies throughout the world to alert the public when a tornado has been reported or indicated by weather radar within the ...

'' (''TOR'') - A tornado is occurring or is imminent as one is sighted or is suggested by

radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor v ...

. * Tornadocyclone - The parent circulation of a tornado. This may refer to a low-level

. * ''

Tornadogenesis Tornadogenesis is the process by which a tornado forms. There are many types of tornadoes and these vary in methods of formation. Despite ongoing scientific study and high-profile research projects such as VORTEX, tornadogenesis is a volatile pro ...

'' - The process leading to tornado formation. * Tornadolysis - The process leading to tornado decay and death. * ''

TORRO The Tornado and Storm Research Organisation (TORRO) was founded by Terence Meaden in 1974. Originally called the Tornado Research Organisation it was expanded in 1982 following the inclusion of the Thunderstorm Census Organisation (TCO) after the d ...

'' (''TORnado and storm Research Organisation'') - * ''

TORRO scale The TORRO tornado intensity scale (or T-Scale) is a scale measuring tornado intensity between T0 and T11. It was proposed by Terence Meaden of the Tornado and Storm Research Organisation (TORRO), a meteorological organisation in the United Kingdo ...

'' - A tornado rating scale developed by Terence Meaden of

classifying tornadoes in the UK from T0-T10 based on intensity. * '' TOTO'' (''TOtable Tornado Observatory'') - * Transverse rolls - * Trigger - (slang) * ''

Tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dep ...

'' (TC) - * '' Trough'' - * Tube - (slang) A storm chaser term for a tornado. * ''

Turbulence In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...

'' - * Twister - (slang) A colloquial term for a tornado. Also, a major theatrical film about storm chasing released in 1996. * ''

TWISTEX TWISTEX (a backronym for Tactical Weather-Instrumented Sampling in/near Tornadoes Experiment) was a tornado research experiment that was founded and led by Tim Samaras of Bennett, Colorado, US, that ended in the deaths of three researchers in ...

'' (''Tactical Weather-Instrumented Sampling in/near Tornadoes EXperiment'') -

U

* ''

Updraft In meteorology, an updraft is a small-scale current of rising air, often within a cloud. Overview Localized regions of warm or cool air will exhibit vertical movement. A mass of warm air will typically be less dense than the surrounding regi ...

'' - * ''

University Corporation for Atmospheric Research The University Corporation for Atmospheric Research (UCAR) is a US nonprofit consortium of more than 100 colleges and universities providing research and training in the atmospheric and related sciences. UCAR manages the National Center for Atmosph ...

'' (''UCAR'') - * '' UTC'' (''Coordinated Universal Time'') -

V

* Vault - * V notch - * Velocity couplet - * Vent shear or vent wind - * Very long track tornado (VLT) - * Violent tornado - A tornado rated F4-F5, EF4-EF5, or T8-T11. * ''

Vortex In fluid dynamics, a vortex ( : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in ...

'' - * '' Vortex breakdown'' - * '' Vortex stretching'' - * ''

VORTEX projects The Verification of the Origins of Rotation in Tornadoes Experiment (or VORTEX) are field experiments that study tornadoes. VORTEX1 was the first time scientists completely researched the entire evolution of a tornado with an array of instrumentat ...

'' - * ''

Vorticity In continuum mechanics, vorticity is a pseudovector field that describes the local spinning motion of a continuum near some point (the tendency of something to rotate), as would be seen by an observer located at that point and traveling along wi ...

'' - * Vorticity maximum (vort max) - * Vorticity minimum -

W

* '' Wall cloud'' - * Warm air advection (WAA) - * ''

Warm front A warm front is a density discontinuity located at the leading edge of a homogeneous warm air mass, and is typically located on the equator-facing edge of an isotherm gradient. Warm fronts lie within broader troughs of low pressure than cold f ...

'' - * '' Warning Decision Training Branch'' (''WDTB'') - * ''

Waterspout A waterspout is an intense columnar vortex (usually appearing as a funnel-shaped cloud) that occurs over a body of water. Some are connected to a cumulus congestus cloud, some to a cumuliform cloud and some to a cumulonimbus cloud. In the ...

'' - * '' Weak echo region'' (''WER'') - * Weak tornado - A tornado rated F0-F1, EFO-EF1, T0-T3. * ''

Weather map A weather map, also known as synoptic weather chart, displays various meteorological features across a particular area at a particular point in time and has various symbols which all have specific meanings. Such maps have been in use since the mi ...

'' - * ''

Weather Prediction Center The Weather Prediction Center (WPC), located in College Park, Maryland, is one of nine service centers under the umbrella of the National Centers for Environmental Prediction (NCEP), a part of the National Weather Service (NWS), which in turn is ...

'' (''WPC'') - * ''

Weather radar Weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, and estimate its type (rain, snow, hail etc.). Modern weather radars are mostly pulse- ...

'' - * ''

Weather satellite A weather satellite or meteorological satellite is a type of Earth observation satellite that is primarily used to monitor the weather and climate of the Earth. Satellites can be polar orbiting (covering the entire Earth asynchronously), or ...

'' - * '' Weather surveillance radar'' (''WSR'') - * '' Weatherwise'' - A photographically adorned general interest weather magazine that frequently publishes articles on tornadoes and other severe weather. * Wedge tornado - (slang) Storm chaser slang for a very large tornado. Typically a wedge tornado is defined as one that is wider at ground level than it is tall (from ground to cloud base). * ''

Whirlwind A whirlwind is a weather phenomenon in which a vortex of wind (a vertically oriented rotating column of air) forms due to instabilities and turbulence created by heating and flow (current) gradients. Whirlwinds occur all over the world and i ...

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Wind Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ...

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Windstorm A storm is any disturbed state of the natural environment or the atmosphere of an astronomical body. It may be marked by significant disruptions to normal conditions such as strong wind, tornadoes, hail, thunder and lightning (a thunderst ...

'' - * '' Wind direction'' - * '' Wind profiler'' - * ''

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Wind speed In meteorology, wind speed, or wind flow speed, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in temperature. Wind speed is now commonly measured with an anemometer. Wind speed ...

'' - * Wind Science and Engineering Research Center (''WiSE'') - * '' Winter waterspout'' - * ''

World Meteorological Organization The World Meteorological Organization (WMO) is a specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics. The WMO originated from the Inter ...

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Z

* Zulu (Z) - Zulu is a phonetic alphabet word for Z, which is an abbreviation used in timecodes to represent UTC.

References

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External links

Glossary of Meteorology
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NWS Glossary
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Tornado FAQ
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Storm spotter glossary
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TheWeatherPrediction.com
(Jeff Haby)
WW2010 Helper Section Index
(

University of Illinois at Urbana-Champaign The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the Un ...

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Basic Meteorological Terminology
(Paul Sirvatka,

College of DuPage College of DuPage is a public community college with its main campus in Glen Ellyn, Illinois. The college also owns and operates facilities in the Illinois communities of Addison, Carol Stream, Naperville and Westmont. With more than 20,000 ...

) Severe weather and convection Tornado-related lists Tornado terms Weather-related lists

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See also

References

External links