Meteorology and atmospheric science terminology · MLC-0110

Meteorology and atmospheric science terms: A (879)

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• Angle of arrivalThe direction from which an electromagnetic wave, such as a radio signal or a radar pulse, is received by an...
• Angle of incidenceThe angle between the direction of an incoming ray or wave and the normal (a line perpendicular) to the...
• Angle of reflectionThe angle between the direction of a reflected ray and the normal (a line perpendicular to the surface) at...
• Angle of refractionThe angle between the direction of a refracted ray or wave and the normal (a line perpendicular) to the...
• Angola CurrentA warm, southward-flowing ocean current found in the eastern South Atlantic Ocean along the coast of...
• Angola-Benguela frontA prominent oceanographic boundary located off the southwestern coast of Africa, separating the warm, saline...
• AngstromA unit of length equal to 10⁻¹⁰ meters, or 0.1 nanometers. It is commonly used in atmospheric science to...
• Ångström compensation pyrheliometerA precision instrument used to measure the intensity of direct solar radiation. It operates on the principle...
• Ångström pyrgeometerAn instrument designed to measure the net longwave radiation flux from the atmosphere, specifically the...
• Ångström turbidity coefficientA parameter that quantifies the atmospheric turbidity, or the reduction in solar radiation due to scattering...
• Angular momentumA vector quantity measuring the rotational motion of a body or fluid parcel about an axis, equal to the...
• Angular resolutionThe ability of an imaging system or sensor to distinguish between two objects that are close together in...
• Angular spreadingThe lateral spreading of ocean waves in direction as they travel out of the area where the wind generated...
• Angular velocityThe rate at which an object or a system rotates or revolves around an axis, expressed as the angle traversed...
• Angular velocity of the earthThe rate at which the Earth rotates on its axis, which is approximately 7.292 x 10⁻⁵ radians per second. This...
• Angular wavenumberA measure of the spatial frequency of a wave, defined as 2π divided by the wavelength. It represents the...
• Angularity correctionA correction in stream gauging applied when the current crosses the measurement section at an angle instead...
• Angular-momentum balanceAn application of conservation of angular momentum to the atmosphere, in which the rate of change of the...
• Angular-spreading factorThe ratio of the wave energy actually present at a point to the energy that would be present there if the...
• AnhyetismA prolonged period of extreme dryness or absence of precipitation in a particular region. This condition...
• AnisotropicDescribing a medium or material whose physical properties, such as thermal conductivity or light absorption...
• AnisotropyThe property of being anisotropic, where a material or system exhibits different characteristics when...
• Anniversary windsA general designation for any wind that recurs predictably at about the same time each year due to seasonal...
• Annual cycleThe recurring pattern of meteorological or climatological variables that completes a full oscillation over a...
• Annual Exceedance ProbabilityThe probability that a stream reach will have a flow of a certain magnitude in any given year.
• Annual exceedance seriesA hydrologic and climatic series made up of the N largest independent events in an N-year record, taken...
• Annual floodThe highest instantaneous peak discharge of a river or stream that occurs within a given water year. This...
• Annual flood seriesA statistical compilation of the maximum instantaneous peak discharge values for a specific river or stream...
• Annual maximum seriesA statistical series composed of the single largest value of a particular meteorological or hydrological...
• Annual minimum seriesA dataset constructed by selecting the single lowest value of a hydrometeorological variable, such as river...
• Annual rangeThe difference between the highest and lowest values of a meteorological variable, such as temperature...
• Annual runoffThe total volume of water that flows from a drainage basin over the course of a year, typically measured in...
• Annual seriesA statistical dataset where a single value, representing either the maximum or minimum occurrence of a...
• Annual storageA reservoir capacity sized to hold the runoff of a watershed for one year, so that flow can be regulated...
• AnomalousDescribing a deviation from the expected, average, or normal conditions of a meteorological or climatological...
• Anomalous propagationThe unusual bending or ducting of electromagnetic waves, particularly radar signals, in the lower atmosphere...
• Anomalous refractionThe deviation of light or other electromagnetic waves from their normal path as they pass through the...
• AnomalyThe difference between an observed value of a meteorological or climatological variable and its long-term...
• Anomaly correlationA statistical measure used to assess the skill of numerical weather prediction models by comparing the...
• Antarctic airA very cold, dry, and stable air mass that originates over the Antarctic continent and surrounding ice...
• Antarctic anticycloneA persistent high-pressure system centered over the Antarctic continent, characterized by subsiding cold...
• Antarctic Bottom WaterAABW is a very cold, dense, and saline water mass that forms in the Weddell Sea and Ross Sea around...
• Antarctic CircleThe parallel of latitude approximately 66.5 degrees South of the Equator, marking the northernmost extent...
• Antarctic Circumpolar CurrentThe largest ocean current on Earth, flowing eastward around Antarctica without encountering any continental...
• Antarctic divergenceA zone in the Southern Ocean where surface waters move away from the Antarctic continent, leading to...
• Antarctic frontThe semipermanent, semicontinuous front in the Southern Hemisphere between the cold air over the Antarctic...
• Antarctic Ice SheetThe continental glacier covering more than 98 percent of Antarctica, representing the largest single mass of...
• Antarctic Intermediate WaterA distinct water mass formed in the Southern Ocean, characterized by relatively low salinity and temperature...
• Antarctic ozone holeA severe depletion of stratospheric ozone over the Antarctic continent that occurs annually during the...
• Antarctic Polar FrontA major oceanic frontal zone in the Southern Ocean, representing the most prominent and northernmost boundary...
• Antarctic sea smokeA type of steam fog that forms over extremely cold open water in the Antarctic region when very cold, dry air...
• Antarctic stratospheric vortexA large-scale, persistent cyclonic circulation in the middle and lower stratosphere that forms over...
• Antarctic Surface WaterThe cold, relatively fresh layer of water found at the surface of the Southern Ocean, particularly south of...
• Antarctic ZoneThe region of the far Southern Hemisphere polewards of the Antarctic Circle at about 66.5 degrees South...
• AntecedentThe pre-existing environmental conditions of the atmosphere, soil, or a water body before a specific...
• Antecedent precipitation indexA numerical value representing the cumulative effect of previous rainfall on soil moisture conditions...
• Antecedent soil moistureThe amount of water present in the soil prior to a particular meteorological event, such as a new rainfall or...
• Antedecent precipitation index(Abbrev. API) - an index of moisture stored within a drainage basin before a storm.
• AntennaA device designed to transmit or receive electromagnetic waves, commonly used in meteorology for radar...
• Antenna feedA component of a radar system that directs electromagnetic energy from the transmitter to the antenna, and...
• Antenna gainA measure of an antenna's ability to direct radio frequency energy in a specific direction compared to an...
• Antenna limitThe lowest linear depolarization ratio that a polarimetric weather radar can measure reliably, set by the...
• Antenna patternA graphical representation of the spatial distribution of the radiated or received power of an antenna...
• Antenna temperatureA measure of the radiation power collected by an antenna from its surroundings, stated as the temperature of...
• Anthelic arcsRare optical phenomena appearing as bright arcs or segments of circles in the sky, opposite the sun. They...
• AnthelionA rare halo phenomenon appearing as a bright, white spot directly opposite the sun in the sky, at the same...
• AnthropogenicDescribing an effect, process, or substance that results from human activities rather than natural causes. In...
• Anthropogenic climate changeAlterations to the Earth's climate system primarily caused by human activities, particularly the emission of...
• Anthropogenic emissionsGases, aerosols, or particulate matter released into the atmosphere as a direct or indirect result of human...
• Anthropogenic heatHeat released into the atmosphere as a direct result of human activities, such as energy consumption from...
• Anthropogenic sourceA pollutant source caused or produced by humans.
• Anticrepuscular raysBeams of sunlight that appear to converge at the antisolar point, the point on the celestial sphere directly...
• AnticyclogenesisThe atmospheric process of development or intensification of an anticyclone, which is a large-scale...
• AnticyclolysisThe process of weakening or dissipation of an anticyclone, a high-pressure system. This occurs when the...
• AnticycloneA large-scale atmospheric circulation system characterized by high atmospheric pressure at its center, with...
• AnticyclonicRelating to or characteristic of an anticyclone, a high-pressure system where air descends and diverges at...
• Anticyclonic circulationThe rotational flow of air around a high-pressure center, characterized by divergence at the surface and...
• Anticyclonic rotationThe circulation of winds around a high-pressure system, characterized by a clockwise flow in the Northern...
• Anticyclonic shearHorizontal wind shear that tends to spin air parcels in the anticyclonic sense, which means clockwise in the...
• Antihail rocketA rocket designed to disperse cloud-seeding agents, such as silver iodide, into hail-producing thunderstorms...
• Anti-icingA proactive treatment or system designed to prevent the formation and adhesion of ice on a surface. In...
• Antilles CurrentA warm Atlantic current flowing northwestward along the northern, seaward side of the Greater Antilles and...
• AntilogThe mathematical function that is the inverse of a logarithm, used in atmospheric science to convert a value...
• AntipleionA center of strong negative departure of a meteorological element, such as pressure or temperature, from its...
• AntiprotonAn elementary particle with the same mass as a proton but with a negative electric charge, constituting the...
• Anti-sea breezeThe return current aloft that blows from land toward the sea above a sea breeze, opposite to the onshore...
• Antisolar pointThe imaginary point on the celestial sphere located exactly 180 degrees from the sun's position, as viewed by...
• AntitradesWinds that blow above the trade winds, typically from the southwest in the Northern Hemisphere and from the...
• Antitwilight archA broad, diffuse band of pinkish or purplish light seen above the eastern horizon at sunset or above the...
• Anti-windThe upper or return branch of an along-valley wind system, as confined within a valley, and blowing in a...
• AnvilThe flattened, ice-crystal-dominated top of a mature cumulonimbus cloud, which spreads out horizontally when...
• Anvil cloudA cumulonimbus cloud that has reached the tropopause, causing its top to spread out horizontally into a...
• Anvil crawler[Slang], a lightning discharge occurring within the anvil of a thunderstorm, characterized by one or more...
• Anvil domeA large overshooting top or penetrating top.
• Anvil rolloverSlang for a circular or semicircular lip of clouds along the underside of the upwind part of a back-sheared...
• Anvil zitsSlang for frequent (often continuous or nearly continuous), localized lightning discharges occurring from...
• AOArctic Oscillation - the Arctic Oscillation is a pattern in which atmospheric pressure at polar and middle...
• AOAAt or above
• AOBAt or below
• AOPAAircraft Owners and Pilots Association
• APAnomalous Propagation. Radar term for false (non-precipitation) echoes resulting from nonstandard propagation...
• Ap indexA planetary index that quantifies the daily average level of geomagnetic activity, derived from K-indices...
• ApaapaaA Hawaiian name for a strong, gusty wind that blows at times off the northern coast of the Kohala district on...
• APDOn a buoy report, the average wave period (seconds) of all waves during the 20-minute period.
• AperiodicDescribing a phenomenon or process that does not exhibit a regular, repeating cycle or pattern over time. In...
• ApertureThe opening in a meteorological instrument through which electromagnetic radiation enters and reaches the...
• AphelionThe point in Earth's elliptical orbit at which it is farthest from the Sun, about 152.1 million kilometers...
• ApheliotesThe classical Greek personification of the east wind, often depicted as a young man with curly hair. In...
• API methodIn hydrologic terms, a statistical method to estimate the amount of surface runoff which will occur from a...
• Apogean tideA tide that occurs when the Moon is at its apogee, its farthest point from Earth in its elliptical orbit. Due...
• ApogeeThe point in the orbit of a satellite or other body around Earth where it is farthest from Earth. The Moon...
• Apparent forceA fictitious force introduced into Newton's second law of motion to account for the effects of a non-inertial...
• Apparent gravityThe net force experienced by an object on the surface of a rotating planet, which is the vector sum of the...
• Apparent groundwater velocityThe specific discharge of groundwater, calculated as the volumetric flow rate divided by the total...
• Apparent horizonThe visible line where the Earth's surface or sea appears to meet the sky, as observed from a specific...
• Apparent solar dayThe time interval between two successive transits of the true Sun across the local meridian. This duration...
• Apparent stressA fictitious stress in a fluid that arises from the time-averaging of the equations of motion for a turbulent...
• Apparent temperatureA measure of human discomfort due to combined heat and humidity (e.g., heat index).
• Apparent windThe speed and true direction from which the wind appears to blow with reference to a moving point. Sometimes...
• Applications Technology SatelliteA series of experimental geostationary satellites launched by NASA from 1966 to 1974, designed to test new...
• Applied climatologyThe practical application of climatological data and knowledge to solve problems in human activities and...
• Applied hydrologyThe practical application of hydrological principles to design and manage water resources projects and solve...
• Applied meteorologyThe practical use of meteorological science and data to address real-world problems and support...
• Approach velocityThe mean velocity of a fluid flowing in the approach channel leading to a hydraulic structure, obstruction...
• Approach visibilityThe horizontal distance a pilot can see forward from the cockpit of an aircraft during the approach phase of...
• Approach-light contact heightThe height above the runway threshold at which a pilot of a landing aircraft can first see the approach...
• APRCHApproach
• APRCHGapproaching
• APRNTapparent
• APSTAviation Products and Services Team
• AquicludeIn hydrologic terms, a formation which contains water but cannot transmit it rapidly enough to furnish a...
• AquiferA geological formation, group of formations, or part of a formation that contains sufficient saturated...
• Aquifer systemA heterogeneous body of permeable and less permeable geologic materials that functions as a single...
• AquifugeIn hydrologic terms, a geologic formation which has no interconnected openings and cannot hold or transmit...
• AquitardA geological formation that is saturated and transmits water at a very slow rate, acting as a semi-confining...
• AracatyA wind of the interior of Ceara, in northeastern Brazil, that comes from the sea every afternoon and evening...
• Arago distanceThe angular distance from the antisolar point to the Arago neutral point, the spot in the sky above the...
• Arago pointA neutral point in the sky where the polarization of scattered skylight is zero. This point is located...
• Arakawa JacobianA finite-difference approximation of the Jacobian operator, commonly used in numerical weather prediction and...
• ARAMAviation, Range, and Aerospace Meteorology
• Arc cloudA low, horizontal, arc-shaped cloud formation that often appears at the leading edge of a thunderstorm or...
• Arc dischargeA type of electrical breakdown in a gas that generates a sustained, high-current plasma discharge between two...
• Arch damA concrete arch dam is used in sites where the ratio of width between abutments to height is not great and...
• Arch Filament SystemIn solar-terrestrial terms, a bright, compact plage crossed by a system of small, arched filaments, which is...
• Arched squallA squall whose advancing cloud rises from the horizon in the shape of an arch, a term from older marine...
• Archimedes's principleA fundamental principle stating that an object wholly or partly immersed in a fluid experiences an upward...
• Arcs of LowitzA rare, usually faint set of halo arcs that extend upward and downward from the parhelia, or sundogs, toward...
• ArcticThe region within the Arctic Circle, or, loosely, northern regions in general, characterized by very low...
• Arctic airA type of air mass that originates over the Arctic Ocean and surrounding landmasses, characterized by...
• Arctic Bottom WaterThe dense water filling the deepest layers of the Arctic Ocean basins, with temperatures slightly below 0...
• Arctic CircleAn imaginary circle of latitude on Earth, approximately 66.5 degrees North, that marks the southernmost limit...
• Arctic desertA polar desert biome characterized by extremely low temperatures, very little precipitation, and sparse...
• Arctic frontA boundary separating very cold arctic air from less cold, but still cold, polar air. This frontal zone is...
• Arctic hazeA widespread, brownish-red haze observed in the Arctic atmosphere, particularly during late winter and...
• Arctic highA weak area of high pressure that appears on mean sea-level pressure charts over the Arctic Basin during late...
• Arctic Intermediate WaterA water mass in the Arctic Ocean situated between the colder, fresher Arctic Surface Water and the denser...
• Arctic mistA very light ice fog, consisting of suspended ice crystals, that forms in extremely cold arctic air. Because...
• Arctic oscillation(abbrev. AO)- The Arctic Oscillation is a pattern in which atmospheric pressure at polar and middle latitudes...
• Arctic packThe extensive body of sea ice that covers a large portion of the Arctic Ocean, persisting through multiple...
• Arctic Polar FrontA persistent oceanographic boundary zone in the Nordic Seas and Barents Sea that separates cold, low-salinity...
• Arctic sea smokeA type of steam fog that forms when very cold arctic air moves over relatively warmer open water, such as...
• Arctic stratospheric vortexA large-scale, persistent cyclonic circulation of air in the stratosphere over the Arctic region during the...
• Arctic Surface WaterThe cold, low-salinity layer of water occupying the upper 50 meters of the Arctic Ocean. Its properties are...
• Arctic tree lineThe northernmost limit where trees can grow, marking the transition from boreal forest to tundra. This...
• Arctic ZoneA geographical region surrounding the North Pole, characterized by extremely cold temperatures, permafrost...
• Arctic-alpineDescribing plant and animal species, or ecological conditions, found in both arctic and alpine environments...
• ArcusA low, horizontal cloud formation that appears as a dense, accessory cloud with a ragged or smooth...
• Area averageA statistical measure representing the mean value of a meteorological variable over a defined geographical...
• Area forecastA forecast of cloud cover, visibility, weather, icing, and turbulence expected over a large region, prepared...
• Area forecast discussionThis National Weather Service product is intended to provide a well-reasoned discussion of the meteorological...
• Area Hydrologic DiscussionA short range, episodic, discussion and graphic which highlights locations across the nation that may be...
• Area of influenceThe spatial extent over which a particular meteorological phenomenon or observation has a discernible impact...
• Area sourceAn array of pollutant sources, so widely dispersed and uniform in strength that they can be treated in a...
• Area wide hydrologic prediction system(Abbrev. AWHPS) - A computer system which automatically ingests areal flash flood guidance values and WSR-88D...
• Area-capacity curveIn hydrologic terms, a graph showing the relation between the surface area of the water in a reservoir, the...
• Area-elevation curveA graphical representation showing the relationship between the cumulative surface area of a drainage basin...
• Areal precipitationThe average depth of precipitation that falls over a specified geographic area, such as a watershed or river...
• Areal reduction factorA factor, never above one, that converts a point rainfall depth of a given duration and return period into...
• ARFORAn abbreviation for an area forecast, typically used in aviation meteorology. It provides a generalized...
• ARFOTAn area forecast, usually for aviation, issued with its units in the English system, for example feet and...
• ArgonAn inert, noble gas that is the third most abundant component of Earth's atmosphere, after nitrogen and...
• ArgosA satellite-based system that collects, processes, and disseminates environmental data from platforms around...
• ArheicDescribing a region or area that lacks any surface drainage or organized river systems, meaning water does...
• AridAn adjunctive applied to regions where precipitation is so deficient in quantity, or occurs at such times...
• Arid zoneA region characterized by a severe lack of available water, to the extent of hindering or preventing the...
• AridityThe degree to which a climate lacks sufficient moisture to support abundant plant life, resulting from a...
• Aridity coefficientA dimensionless index used to quantify the degree of dryness in a climate, calculated as the ratio of annual...
• Aridity indexA numerical indicator that quantifies the degree of dryness of a climate at a given location. It is...
• Arid-zone hydrologyThe scientific study of water movement and distribution within arid and semi-arid regions, focusing on the...
• ARINCAeronautical Radio, Incorporated
• Arithmetic meanA statistical measure representing the sum of a set of values divided by the number of values in the set. It...
• ArmouringA natural process where finer sediment particles are eroded from a streambed or land surface, leaving behind...
• ARNDAround
• Aromatic hydrocarbonsA class of organic compounds containing one or more benzene rings, which are characterized by delocalized pi...
• ARRArrive/Arrival
• Arrhenius equationA formula giving the temperature dependence of a reaction rate constant, in which the rate constant equals a...
• ArroyoA steep-sided, flat-bottomed channel or gully carved by intermittent or ephemeral streams in arid and...
• ARSIAtmospheric Research System, Inc.
• ARTThe Automatic Radiotheodolite. A ground-based radio direction finder that automatically tracks a ballon-borne...
• ARTCCAir Route Traffic Control Center
• Artesian aquiferA confined aquifer where groundwater is under sufficient pressure to rise above the top of the aquifer in a...
• Artesian basinA large geological structure consisting of one or more artesian aquifers, where groundwater is confined under...
• Artesian wellA well drilled into a confined aquifer where the internal pressure causes water to rise above the top of the...
• Artificial climateA controlled atmospheric environment created and maintained by human intervention, typically within enclosed...
• Artificial controlThe deliberate human intervention in atmospheric processes to modify weather or climate conditions for...
• Artificial horizonA device that provides an aircraft pilot with an artificial reference to the horizon, indicating the...
• Artificial ice nucleusA substance introduced into a cloud to promote the formation of ice crystals at temperatures warmer than they...
• Artificial intelligenceThe development of computer systems capable of performing tasks that typically require human intelligence...
• Artificial precipitationRain, snow, or other forms of moisture that fall from clouds as a result of human intervention, rather than...
• Artificial rechargeThe process of deliberately adding water to groundwater aquifers through human activities, such as spreading...
• AS(NOTE: if this appears in an Area Forecast Discussion or other text product in context as the word "as,"...
• ASAP1. AHOS SHEF Automatic Processing System
• ASAPTRANThe software component of ASAP.
• ASBAviation Support Branch
• Ascending nodeThe point in an orbit where a satellite or celestial body crosses the equatorial plane from south to north...
• AshFine, solid particles ejected into the atmosphere during volcanic eruptions or large fires, composed of...
• Ash devilsSmall, swirling columns of ash and dust that form over hot, dry surfaces, similar in mechanism to dust...
• Ashfall advisoryThis product is issued for a volcano undergoing a minor eruption where the public will be affected by a...
• Ashfall warningThis product is issued for a volcano undergoing a major eruption where the public will be affected to a...
• ASLAbove Sea Level
• ASOSAutomated Surface Observing System. A list of stations currently active and available through the NWS website...
• ASOS IDsEach Automated Surface Observing System an a four character identifier assigned to it. A list of stations...
• AspectThe compass direction that a slope or surface faces, influencing its exposure to solar radiation, wind, and...
• Aspect ratioThe ratio of an object's width to its height, or in atmospheric science, it can refer to the ratio of...
• Aspirated thermometerA temperature-measuring device where air is actively drawn over the thermometer bulb to obtain a more...
• Aspiration meteorographA meteorological instrument that continuously records multiple atmospheric variables, such as temperature and...
• Aspiration thermographA recording thermometer that actively draws air over its temperature-sensing element to provide a more...
• ASR-9Airport Surveillance Radar (FAA)
• Assmann psychrometerA specific type of aspiration psychrometer known for its high accuracy in measuring atmospheric humidity. It...
• Associated principal userA Principal User with dedicated communications to a WSR-88D unit.
• Astronomical dawnThe time at which the sun is 18 degrees below the horizon in the morning. Astronomical dawn is that point in...
• Astronomical duskThis is the time at which the sun is 18 degrees below the horizon in the evening. At this time the sun no...
• Astronomical horizonThe great circle on the celestial sphere whose plane is perpendicular to the observer's zenith-nadir line...
• Astronomical refractionThe apparent displacement of celestial objects from their true positions due to the bending of light rays as...
• Astronomical twilightThe period of twilight that begins or ends when the Sun's center is 18 degrees below the horizon. During this...
• Astronomical unit(abbrev. AU)- The mean earth-sun distance, equal to 1.496x10^(13) cm, or 214.94 solar radii.
• Asymmetry factorA parameter used in radiative transfer calculations to describe the angular distribution of scattered...
• Asymptotic expansionA mathematical series that approximates a function for large values of its argument, where the terms of the...
• Asynchronous communicationA method of data transmission where data blocks are sent independently without a shared clock signal, relying...
• Asynoptic observationA meteorological measurement taken at a time not synchronized with the standard synoptic observation times...
• ATCAir Traffic Control
• ATDTDCSAutomated Tone Dial Telephone Data Collection System - Data collection system where cooperative observers...
• Athos fall windA fall wind off Mount Athos in Greece, in which dense cold air from the top of the slope pours downhill...
• Atlantic WaterA distinct water mass originating from the North Atlantic Ocean, characterized by relatively high salinity...
• AtmometerAn instrument used to measure the rate of evaporation from a standardized wet surface, providing an...
• AtmometryThe measurement of evaporation from a free water surface into the atmosphere. This process quantifies the...
• AtmoradiographAn instrument that counts how often atmospherics, the radio impulses produced by lightning discharges, exceed...
• AtmosphereThe gaseous envelope surrounding a celestial body, held in place by gravity. Earth's atmosphere is a mixture...
• Atmosphere-mixed layer ocean modelA climate model that couples an atmospheric general circulation model to a simple ocean represented only by a...
• Atmosphere-ocean interactionThe continuous exchange of energy, momentum, and matter across the boundary between the atmosphere and the...
• Atmospheric attenuationThe reduction in the intensity of electromagnetic radiation or sound waves as they pass through the Earth's...
• Atmospheric boundary layerThe lowest part of the troposphere, directly influenced by the Earth's surface and responding to surface...
• Atmospheric chemistryThe study of the chemical composition of the Earth's atmosphere, including the sources, reactions, transport...
• Atmospheric circulation modelA numerical model that simulates the large-scale movement of air in the Earth's atmosphere, driven by...
• Atmospheric correctionA process applied to remotely sensed data to remove the effects of the atmosphere on the measured signal...
• Atmospheric demandThe potential rate at which water can evaporate and transpire from a surface into the atmosphere, driven by...
• Atmospheric disturbanceAny deviation from the average or undisturbed state of the atmosphere, often referring to a localized region...
• Atmospheric ductingThe propagation of electromagnetic waves or sound waves within a confined atmospheric layer, where changes in...
• Atmospheric dustFine solid particles suspended in the Earth's atmosphere, originating from natural sources such as deserts...
• Atmospheric dynamicsThe study of the forces and motions within the Earth's atmosphere, including winds, pressure systems, and...
• Atmospheric electric fieldThe electric field that exists naturally within the Earth's atmosphere, primarily due to the separation of...
• Atmospheric electricityThe study of electrical phenomena occurring in the Earth's atmosphere, including lightning, fair-weather...
• Atmospheric ionizationThe process by which atoms or molecules in the atmosphere gain or lose electrons, resulting in the formation...
• Atmospheric layerA distinct region within the Earth's atmosphere characterized by specific temperature profiles, chemical...
• Atmospheric modelA mathematical representation of the physical and chemical processes occurring in the Earth's atmosphere...
• Atmospheric opticsThe study of optical phenomena that occur in the Earth's atmosphere, resulting from the interaction of light...
• Atmospheric oscillationA recurring, quasi-periodic variation in atmospheric circulation patterns or meteorological variables over a...
• Atmospheric ozoneA triatomic molecule of oxygen, O3, found in Earth's atmosphere. It absorbs harmful ultraviolet radiation...
• Atmospheric phenomenonAn observable event occurring within the Earth's atmosphere, resulting from physical or chemical processes...
• Atmospheric polarizationThe partial polarization of sunlight scattered by molecules and aerosols in the Earth's atmosphere. This...
• Atmospheric pressureThe force exerted by the weight of the air column above a given point on the Earth's surface. This pressure...
• Atmospheric radiationElectromagnetic energy emitted or absorbed by gases, aerosols, and clouds within the Earth's atmosphere. This...
• Atmospheric radiation budgetThe balance between incoming solar radiation absorbed by the Earth-atmosphere system and outgoing terrestrial...
• Atmospheric refractionThe bending of light or other electromagnetic waves as they pass through the Earth's atmosphere, caused by...
• Atmospheric regionA broad classification of the Earth's atmosphere based on distinct physical characteristics, often related to...
• Atmospheric riverA narrow corridor of concentrated moisture in the atmosphere, often thousands of kilometers long and hundreds...
• Atmospheric scienceThe interdisciplinary study of the Earth's atmosphere, encompassing its physical, chemical, and dynamic...
• Atmospheric shellA conceptual layer of the Earth's atmosphere, often used to describe distinct regions based on temperature...
• Atmospheric soundingA measurement of atmospheric properties, such as temperature, humidity, and wind speed, as a function of...
• Atmospheric thermodynamicsThe application of thermodynamic principles to understand energy transformations and phase changes within the...
• Atmospheric tideGlobal-scale oscillations in atmospheric pressure, temperature, and wind that are primarily driven by solar...
• Atmospheric transportThe movement of air and the substances it contains, such as heat, moisture, pollutants, and aerosols, over...
• Atmospheric water budgetAn accounting of the inputs, outputs, and storage of water within a defined volume of the atmosphere. The...
• Atmospheric waveA disturbance that propagates through the atmosphere, transferring energy without necessarily transporting...
• Atmospheric windowA range of wavelengths in the electromagnetic spectrum where the atmosphere is relatively transparent to...
• AtmosphericsNaturally occurring electromagnetic impulses, often heard as crackling or hissing sounds on radio receivers...
• ATMPOn a buoy report, the air temperature (Celsius).
• Atomic numberA fundamental property of a chemical element, defined as the total count of protons found within the nucleus...
• Attached thermometerA thermometer mounted on the casing of a mercury barometer to indicate the temperature of the mercury column...
• AttachmentThe process by which a free electron or a small, mobile ion joins with a neutral atom or molecule to create a...
• AttenuationThe reduction in the intensity of electromagnetic radiation or sound waves as they pass through a medium...
• Attenuation coefficientA quantitative measure of the rate at which the intensity of radiation or sound decreases as it propagates...
• ATTMAt this time
• AttractorA set of states in a dynamical system towards which the system evolves over time, regardless of the initial...
• Audibility zoneA region surrounding a sound source within which the sound is audible. Atmospheric conditions such as...
• AufeisA type of layered ice formation that occurs in cold regions when groundwater or river water repeatedly...
• Augmented reportA meteorological report prepared by an automated surface weather observing system for transmission with...
• AureoleA small, colored ring or series of rings observed around the sun or moon, typically appearing white or bluish...
• AuroraA natural light display in the Earth's sky, predominantly seen in high-latitude regions, caused by the...
• Aurora australisThe aurora that occurs in the Southern Hemisphere, also known as the Southern Lights. It is a natural light...
• Aurora borealisThe aurora that occurs in the Northern Hemisphere, commonly known as the Northern Lights. This spectacular...
• Aurora polarisA natural light display in the Earth's sky, predominantly seen in high-latitude regions, caused by the...
• Auroral arcA luminous band of light that stretches across the sky, appearing as a relatively stable and continuous...
• Auroral bandsDynamic and often wavy or folded structures of auroral light that appear as elongated ribbons across the sky...
• Auroral coronaA spectacular auroral display that appears when an observer is directly underneath the magnetic field lines...
• Auroral curtainsA common and visually striking form of aurora, resembling shimmering, folded draperies or curtains of light...
• Auroral ovalA continuous, ring-shaped region centered around the Earth's magnetic poles where auroral activity is most...
• Auroral raysColumnar structures of light that extend vertically along magnetic field lines within an auroral display...
• Auroral zoneThe geographical region on Earth where auroral displays are most frequently and intensely observed, typically...
• AustauschThe exchange of properties, such as heat, momentum, or moisture, between different layers of the atmosphere...
• Australasian Mediterranean WaterA tropical water mass formed from Pacific Ocean central water as it passes through the Australasian...
• AustruA warm, very dry local wind of southwestern Romania that blows from the west or southwest across Banat...
• AutanA wind from the southeast that blows across southern and southwestern France, notably over Languedoc and the...
• AutobarotropicSaid of a fluid that is both barotropic and piezotropic, with equal coefficients of barotropy and piezotropy...
• AutobarotropyThe state of a fluid in which barotropy and piezotropy are both present and their coefficients are equal, an...
• AutoconvectionThe spontaneous overturning of an air layer in which temperature falls with height at least as fast as the...
• Autoconvective lapse rateThe environmental lapse rate at which air density is constant with height, equal to gravitational...
• AutoconversionThe process in cloud physics where cloud droplets spontaneously grow large enough to become raindrops without...
• AutocorrelationThe correlation of a time series with a lagged version of itself, indicating the degree of similarity between...
• Autogenous electrificationThe electric charging of an aircraft or other moving object by friction and impact with ice crystals, snow...
• Automated event reporting gage(also see Tipping Bucket Rain Gage); for river stage gages, IFLOWS pressure transducer type gages can be...
• Automated reportA meteorological report prepared by an automated surface weather observing system for transmission, and with...
• Automated Surface Observing SystemThe ASOS program is a joint effort of the National Weather Service (NWS), the Federal Aviation Administration...
• Automatic data processingThe handling of meteorological data through automated electronic systems, from initial collection and quality...
• Automatic evaporation stationA meteorological station equipped with sensors to continuously measure and record the rate of water...
• Automatic gain controlAn electronic circuit within a radio receiver that automatically adjusts its amplification to maintain a...
• Automatic picture transmissionA system for broadcasting analog image data from weather satellites, allowing for direct reception by...
• Automatic stationA meteorological observation site equipped with sensors and data logging systems that automatically measure...
• Automatic tide gaugeAn instrument that continuously and autonomously measures and records the height of the sea level at a...
• Automatic weather stationA self-contained meteorological station that automatically collects and transmits weather data from its...
• Autoregressive processA type of stochastic process where the current value of a variable is linearly dependent on its own previous...
• Autoregressive seriesA type of time series model where the current value of a variable is expressed as a linear function of its...
• AutumnThe season of the year that follows summer and precedes winter, characterized by decreasing temperatures...
• Autumn iceSea ice that forms during the autumn season, typically characterized by its relatively thin and fragile...
• AutumnalRelating to or characteristic of the season of autumn. In meteorology, this describes weather patterns and...
• Autumnal equinoxThe moment when the sun crosses the celestial equator, marking the astronomical beginning of autumn in the...
• AuvergnasseA regional name in the Lyon area for a wind that blows from the Auvergne toward the Lyonnais, which makes it...
• Auxiliary shipA merchant vessel or other non-dedicated research ship that voluntarily participates in meteorological...
• Auxiliary thermometerA small mercury-in-glass thermometer attached to the stem of a reversing thermometer and read at the same...
• Available potential energyThe portion of the total potential energy of an atmospheric or oceanic system that can be converted into...
• Available soil moistureThe amount of water held in the soil that is accessible to plants for transpiration. It represents the...
• Available solar radiationThe portion of solar energy that reaches the Earth's surface and can be absorbed by a particular surface or...
• Available storage capacityThe volume within a reservoir, lake, or soil profile that is empty and available to store additional water...
• Available waterThe portion of water in the soil that can be absorbed by plant roots. It is the difference between the field...
• AvalancheA rapid flow of a large mass of snow, ice, and sometimes rock down a mountainside. These events are triggered...
• Avalanche advisoryA preliminary notification that conditions may be favorable for the development of avalanches in mountain...
• Avalanche windA powerful, turbulent blast of air preceding a large, fast-moving avalanche. This wind is generated by the...
• AVBLAvailable
• Average interstitial velocityThe mean speed at which a fluid, such as air or water, moves through the pore spaces of a porous medium like...
• Average limit of iceThe typical or mean extent of sea ice or glacial ice over a specified period, often determined from...
• Average net balanceThe change in a glacier's mass over a specific period, typically a year, averaged over the entire glacier...
• Average over the spectrumA statistical mean calculated across a range of wavelengths or frequencies within the electromagnetic...
• Average powerThe mean rate at which energy is transferred or work is done over a specified period. In meteorology, it can...
• Average velocityThe total displacement of a fluid parcel or air mass divided by the time taken for that displacement. This...
• AVGAverage
• AVHRRAdvanced Very High Resolution Radiometer. Main sensor on U.S. polar orbiting satellites.
• Aviation forecastA specialized weather prediction tailored to the needs of aircraft operations, providing detailed information...
• Aviation observationA report detailing current weather conditions at an airport or other designated location, specifically...
• Aviation weather forecastA specialized prediction of atmospheric conditions relevant to aircraft operations, detailing expected...
• Aviation weather observationA standardized report of meteorological conditions at an aerodrome, designed to provide pilots and air...
• AVNThe Aviation model (120-hour numerical model of the atmosphere). The output from this model is now part of...
• Avogadro's lawA scientific principle stating that equal volumes of different gases, when held at the same temperature and...
• Avogadro's numberThe number of constituent particles, such as atoms or molecules, that are contained in one mole of a...
• AVPOn a buoy report, Average Wave Period is the average period (seconds) of the highest one-third of the wave...
• AvulsionThe rapid abandonment of a river's established channel to form a new one on its floodplain. This process is...
• AWCAviation Weather Center
• AWHPSArea Wide Hydrologic Prediction System
• AWIPSAdvanced Weather Interactive Processing System. This system replaced the Automation of Field Operations and...
• AWOSAutomated Weather Observation System
• Axial symmetryThe property of an object or system being symmetrical with respect to rotation about a central axis. In...
• Axis of anticycloneThe imaginary line or region of highest pressure that runs through the center of an anticyclonic circulation...
• Axis of contractionA line or direction along which a fluid parcel or air mass is undergoing convergence and reduction in its...
• Axis of depressionThe imaginary line or trough of lowest pressure that extends through the center of a low-pressure system or a...
• Axis of dilatationA line or direction along which a fluid parcel or air mass is undergoing divergence and expansion in its...
• AxisymmetricDescribing a three-dimensional object, flow, or field that is symmetrical around a central axis, meaning its...
• Axisymmetric flowFluid motion where the velocity components and other flow properties are independent of the azimuthal angle...
• Axisymmetric turbulenceTurbulent fluid motion where the statistical properties of the turbulence are invariant under rotation about...
• AzimuthThe horizontal angle measured clockwise from a reference direction, typically true north, to a point of...
• Azimuth angleThe direction or bearing toward which a sloping surface faces (e.g., a north-facing slope has an azimuth...
• Azimuth resolutionThe ability of a radar system to distinguish between two targets at the same range but at different angular...
• Azimuth scaleA graduated circular scale used to measure horizontal angles relative to a fixed reference direction...
• Azores CurrentA warm ocean current that flows eastward from the Grand Banks of Newfoundland, south of the Azores...
• Azores highA large, semi-permanent subtropical high-pressure system centered near the Azores in the North Atlantic...

879 of 10,703 terms in Meteorology and atmospheric science terminology (MLC-0110). Request the full dataset.