Meteorology and atmospheric science terminology · MLC-0110

Meteorology and atmospheric science terms: C (1,017)

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• C1. Degrees Celsius (°C)
• C AMSContinental Air Mass
• C figureA qualitative, single-digit index used to characterize the level of global geomagnetic activity for a given...
• C indexA subjectively assigned daily index of geomagnetic activity, in which observers at magnetic observatories...
• CACloud-to-Air lightning.
• CAACold Air Advection
• CabbelingA process in oceanography where two water masses of different temperatures and salinities, when mixed...
• CableAn insulated wire or bundle of wires used to transmit electrical power or data signals to and from...
• CacimboA period of thick fog and low stratus clouds that occurs along the coast of Angola during the cool, dry...
• CADCold Air Damming. The phenomenon in which a low-level cold air mass is trapped topographically. Often, this...
• CADASCentralized Automated Data Acquisition System - a system of two minicomputers in NWSH.
• Cajú rainsA period of light rainfall that occurs in northeastern Brazil, particularly in the state of Ceará, during the...
• Cake iceA relatively flat piece of floating sea ice less than 20 m across, and therefore smaller than a floe in sea...
• Calendar yearA period of 12 consecutive months beginning on January 1 and ending on December 31. In meteorology, this...
• CalibrationThe process of comparing the output of a measurement instrument against a known standard of greater accuracy...
• Calibration of an instrumentThe process of adjusting a meteorological instrument to provide accurate measurements by comparing its...
• Calibration tankA container holding a fluid with known, stable properties used to calibrate meteorological instruments. The...
• California CurrentA cool ocean current flowing equatorward along the western edge of North America, extending from British...
• California methodA method of frequency analysis in hydrology in which the return period, the average time between events equal...
• California plotting positionA plotting position formula for the probability of exceedance of the m-th largest value in a record of n...
• CalinaA haze prevalent in Spain during the summer, when strong winds raise dust from the dry ground and fill the...
• CalmA state of the atmosphere characterized by the absence of perceptible wind. In meteorological observations, a...
• Calm beltA region of the Earth's atmosphere characterized by consistently light or absent winds. These belts are...
• Calms of CancerA region of persistent high atmospheric pressure and light, variable winds located near the Tropic of Cancer...
• CalorieA unit of energy defined as the amount of heat required to raise the temperature of one gram of water by one...
• CalorimeterAn instrument used to measure the heat absorbed or released during a chemical reaction or physical change. In...
• Calved iceAny piece of ice that has broken off from a larger ice body, such as a glacier, ice shelf, or iceberg. This...
• CalvingThe process by which chunks of ice break off from the edge of a glacier, ice shelf, or iceberg. This occurs...
• CalvusA species of cumulonimbus that has grown from cumulus congestus and whose upper part is losing its sharp...
• Campbell-Stokes recorderAn instrument that measures the duration of bright sunshine in a day by focusing sunlight onto a specially...
• CamposA type of tropical savanna found in central Brazil, characterized by extensive grasslands with scattered...
• Canadian hardness-gaugeAn instrument for measuring the hardness or resistance of layers within a snowpack. It consists of a...
• Canary CurrentA cold ocean current that flows southward along the northwest coast of Africa, originating from the North...
• Cancellation ratioA measure of a Doppler weather radar's ability to suppress unwanted power returns from stationary targets...
• CandelaThe base unit of luminous intensity in the International System of Units (SI). It quantifies the power...
• CandleAn obsolete unit of luminous intensity, superseded by the candela in the International System of Units. It...
• Candle iceA form of decaying columnar ice that develops in late spring or early summer, characterized by long, slender...
• Candlemas Eve windsHeavy winds that often occur in Great Britain in February or March, around Candlemas on 2 February, also...
• CanopyThe uppermost layer of vegetation in an ecosystem, formed by the crowns of trees or other tall plants, which...
• Canopy temperatureThe temperature of the upper surface of a vegetation layer, representing the combined temperature of leaves...
• Canterbury northwesterA warm, dry Foehn wind that affects the Canterbury Plains on the South Island of New Zealand, originating...
• Canting angleThe average angle of orientation of non-spherical hydrometeors, such as raindrops or ice crystals, with...
• Canyon windA localized wind that flows through a canyon or valley, often exhibiting diurnal patterns. During the day...
• CapA layer of stable air aloft that inhibits vertical air movement and suppresses the development of deep...
• Cap cloudA small, stationary cloud that forms immediately above or on the leeward side of a mountain peak, resembling...
• Capacitance rain gaugeA type of rain gauge that measures precipitation by detecting changes in electrical capacitance as water...
• Capacity correctionA correction applied to readings from a fixed-cistern mercury barometer to account for the change in the...
• Capacity of the windThe maximum amount of sediment or other particulate matter that wind can transport under given atmospheric...
• CAPEConvective Available Potential Energy. A measure of the amount of energy available for convection. CAPE is...
• Cape doctorA local name for the strong, persistent southeasterly wind that blows during the summer months in the Cape...
• CapillarityThe phenomenon where a liquid in a narrow tube or porous material rises or falls due to the interplay of...
• Capillarity correctionAn adjustment made to mercury barometer readings to compensate for the depression of the mercury column...
• Capillary actionThe process by which a liquid flows in narrow spaces without the assistance of, or even in opposition to...
• Capillary collectorA device that uses capillary action to gather samples of atmospheric liquid water, such as cloud droplets...
• Capillary conductivityThe ability of a porous medium, such as soil, to transmit water under the influence of capillary forces. This...
• Capillary depressionThe lowering of a liquid's surface in a narrow tube or pore below the level it would otherwise occupy, caused...
• Capillary electrometerAn instrument for detecting and measuring small differences in electrical potential, historically used in...
• Capillary forcesThe intermolecular forces that arise from the surface tension of a liquid in contact with a solid...
• Capillary fringeA zone in the subsurface immediately above the water table where soil pores are saturated with water due to...
• Capillary headThe equivalent height of a column of water that represents the negative pressure or tension with which water...
• Capillary hysteresisThe phenomenon where the relationship between soil water content and capillary pressure (or matric potential)...
• Capillary intersticeA microscopic pore or channel within a porous medium, such as soil or snow, where water can be held by...
• Capillary potentialThe component of the total soil water potential that arises from the forces of capillarity and adsorption...
• Capillary pressureThe pressure difference across the interface between two immiscible fluids within a porous medium, such as...
• Capillary riseThe upward movement of water through small pores or tubes against the force of gravity, driven by surface...
• Capillary suctionThe negative pressure or tension exerted on water within small pores due to surface tension forces, drawing...
• Capillary waterWater held in the small pores and interstices of soil or other porous media by surface tension and adhesive...
• Capillary waveA small, free-surface wave on a liquid where the primary restoring force is surface tension rather than...
• Capillary waves, see Capillary wave
• Capillary zoneUsed interchangably with Capillary Fringe; the soil area just above the water table where water can rise up...
• CapillatusA cloud species designation for cumulonimbus clouds that have developed a distinct fibrous or cirriform...
• Capped columnA composite ice crystal consisting of a hexagonal column with a thin, plate-like crystal attached to one or...
• CAPPIA radar display product that provides a Constant Altitude Plan Position Indicator, showing radar reflectivity...
• CappingA region of negative buoyancy below an existing level of free convection (LFC) where energy must be supplied...
• Capping inversionA stable layer of warm air aloft that inhibits the vertical development of convection, acting as a lid on...
• CAPSCenter for Analysis and Prediction of Storms
• Captive balloon soundingAn atmospheric sounding technique where meteorological instruments are carried aloft by a tethered balloon to...
• CaptureThe process in cloud physics by which a larger falling hydrometeor, such as a raindrop or ice crystal...
• CarabinéA sudden and violent wind, the name used in France and Spain, where it is also called brise carabinée or...
• CarbonA chemical element with the symbol C and atomic number 6 that is a fundamental building block of life and a...
• Carbon assimilationThe process by which living organisms, primarily plants, convert inorganic carbon dioxide from the atmosphere...
• Carbon bond mechanismA condensed chemical scheme used in atmospheric chemistry models to simulate the formation of ozone and other...
• Carbon budgetA balance sheet of carbon exchanges between sources, such as emissions, and sinks, such as uptake, within a...
• Carbon dioxideA colorless, odorless gas composed of one carbon atom and two oxygen atoms, naturally present in the Earth's...
• Carbon dioxide atmospheric concentrationsThe amount of carbon dioxide gas present in the Earth's atmosphere, typically expressed in parts per million...
• Carbon dioxide bandA specific range of wavelengths in the electromagnetic spectrum where carbon dioxide molecules absorb and...
• Carbon dioxide equivalenceA metric for comparing the emissions of different greenhouse gases based on their global warming potential...
• Carbon dioxide fertilizationThe process by which increased atmospheric carbon dioxide concentrations stimulate photosynthesis and growth...
• Carbon dioxide fertilizing effectThe observed increase in photosynthetic rates and biomass accumulation in plants when exposed to elevated...
• Carbon disulfideA colorless, volatile liquid with a distinctive odor, composed of one carbon atom and two sulfur atoms. It is...
• Carbon poolA reservoir within the Earth system where carbon is stored. These pools include the atmosphere, oceans...
• Carbon sinkA natural or artificial reservoir that accumulates and stores carbon-containing chemical compounds for an...
• Carbon sourceAny process or activity that releases carbon dioxide or other carbon-containing compounds into the...
• Carbon tetrachlorideA colorless liquid with a sweet odor, composed of one carbon atom and four chlorine atoms. It was formerly...
• Carbon-black seedingA weather modification technique involving the dispersion of fine carbon black particles into the atmosphere...
• Carbon-film hygrometer elementA sensor component used to measure atmospheric humidity, consisting of a thin film of carbon particles...
• Carbonyl compoundsA class of organic molecules that contain a carbonyl functional group, which consists of a carbon atom joined...
• Carbonyl sulfideA colorless, flammable gas composed of one carbon atom, one oxygen atom, and one sulfur atom. It is the most...
• Carburetor icingThe formation of ice within the carburetor of an internal combustion engine, typically in aircraft, due to...
• Cardinal temperaturesThe set of three temperature thresholds that define the range for a biological process, particularly the...
• Caribbean CurrentA warm, fast-flowing ocean current that transports a large volume of water northwestward through the...
• Carnot cycleAn idealized thermodynamic cycle that describes the maximum possible efficiency for converting heat into...
• Carnot engineAn idealized thermodynamic model for a heat engine that converts thermal energy into mechanical work with the...
• Carrier frequencyThe specific frequency of an electromagnetic wave that is modulated to transmit information. In remote...
• Carrier waveAn electromagnetic wave that is modulated to convey information, such as data or signals. In atmospheric...
• Carrington longitudeA system of fixed longitudes rotating with the sun
• Carry-overThe share of a stream's discharge in a given month or year that was supplied by rain or snow falling in...
• Cartesian coordinatesA system for specifying the position of a point in space using a set of mutually perpendicular axes...
• Cartesian tensorA mathematical object that describes physical quantities whose components transform in a specific way under...
• CascadeA series of sequential processes or events where the output of one stage becomes the input for the next...
• Cascade impactorAn instrument that samples and separates airborne particles into different size fractions based on their...
• Cascade of energyThe process in turbulent fluid flows where kinetic energy is transferred from larger eddies to progressively...
• Cascade showerA phenomenon in the upper atmosphere where a high-energy cosmic ray particle interacts with atmospheric...
• Case-based reasoningAn artificial intelligence approach to problem-solving that is applied to weather forecasting by using past...
• Cassegrainian telescopeA type of reflecting telescope that uses a large concave primary mirror and a smaller convex secondary mirror...
• CastellanusA cloud species in which the upper part has cumuliform turrets, joined by a common base and often arranged in...
• CastellatusA cloud feature, often used interchangeably with castellanus, describing turreted or castle-like extensions...
• Catalina eddyA mesoscale, counter-clockwise rotating eddy that forms in the Southern California Bight, the coastal region...
• Catalytic convertersDevices installed in vehicle exhaust systems that reduce the toxicity of emissions by converting harmful...
• Catalytic cyclesA sequence of chemical reactions where a catalyst is consumed in one step and regenerated in a subsequent...
• CatchThe amount of precipitation, such as rain or snow, collected by a rain gauge or similar instrument over a...
• Catchment areaThe geographical region from which all precipitation and surface runoff drain into a common outlet, such as a...
• CategoricalA National Weather Service precipitation descriptor for a 80, 90, or 100 percent chance of measurable...
• Cathode-ray oscilloscopeAn electronic instrument that displays varying electrical signals as waveforms on a screen. It uses a...
• Cathode-ray radiogoniometerA direction-finding instrument that uses a cathode-ray tube to visually display the bearing of a radio...
• Cathode-ray tubeA vacuum tube containing an electron gun that emits a beam of electrons, which are then deflected and...
• Cation exchange capacityA measure of the total capacity of a soil or other material to hold exchangeable cations, expressed in...
• Cat's noseA traditional English name for a cool wind from the northwest, felt on the face like a light touch. It...
• Cat's pawA pattern of localized, light ripples on an otherwise calm water surface, created by a small-scale, isolated...
• Cauchy numberA dimensionless quantity used in fluid dynamics to represent the ratio of inertial forces to elastic forces...
• Caution stageThe stage which, when reached by a rising stream, represents the level where appropriate officials (e.g...
• CavaliersA regional weather-lore name used near Montpellier in southern France for a short spell around the turn of...
• CavityA hollow space or void within a material or structure, or a region of reduced pressure or density in a fluid...
• Cavity radiometerA type of radiometer designed to measure incident electromagnetic radiation by absorbing it within a...
• CAVOKAn aviation weather reporting code indicating 'Ceiling And Visibility OK,' used when specific favorable...
• CAVUAn aviation weather reporting code meaning 'Ceiling And Visibility Unlimited,' indicating optimal flying...
• CavumA supplementary cloud feature characterized by a well-defined, often circular or elliptical, hole or void...
• CbCumulonimbus cloud, characterized by strong vertical development in the form of mountains or huge towers...
• CBMAMCumulonimbus Mamma
• CCCloud-to-Cloud Lightning
• CCITTConsultative Committee for International Telephone and Telegraph
• CCLConvective Condensation Level- The level in the atmosphere to which an air parcel, if heated from below, will...
• CDcold
• CDBComputing Development Branch (NCEP)
• CDCClimate Diagnostic Center, the mission of the Climate Diagnostics Center (CDC) is to advance national...
• CDDCooling Degree Days- A form of degree day used to estimate energy requirements for air conditioning or...
• CDFNTCold Front
• CDTCentral Daylight Time
• CeilingThe height of the lowest layer of clouds or obscuring phenomena that is reported as broken, overcast, or...
• Ceiling balloonA small, gas-filled balloon released from the ground to determine the height of the cloud base. The balloon's...
• Ceiling classificationA designation of how a reported ceiling height was determined: measured, estimated or indefinite. A measured...
• Ceiling lightA specialized light projector used at night to determine the height of the cloud base. A beam of light is...
• Ceiling-height indicatorAn instrument that projects a modulated beam of light vertically onto a cloud base and measures the height by...
• CeilometerA type of lidar instrument that measures the height of the cloud base and vertical visibility. It emits a...
• CelerityThe speed at which a wave propagates through a medium, representing the phase speed of the wave. It is...
• Celestial equatorAn imaginary great circle on the celestial sphere, lying in the same plane as the Earth's equator. It is an...
• Celestial poleEither of the two points where the Earth's axis of rotation, extended indefinitely, intersects the celestial...
• Celestial sphereAn imaginary sphere of arbitrarily large radius, concentric with the Earth, on which all celestial bodies...
• CellA distinct, localized region of atmospheric activity, often characterized by specific meteorological...
• Cellular circulationAn organized pattern of fluid motion characterized by a network of distinct, repeating cells of rising and...
• Cellular cloud patternAn organized, honeycomb-like arrangement of clouds, visible in satellite imagery, that forms in response to...
• Cellular convectionA convective pattern in which a fluid layer organizes into a regular array of polygonal, often hexagonal...
• CelsiusThe standard scale used to measure temperature in most areas outside the United States. On this scale, the...
• Celsius temperature scaleA thermometric scale where the freezing point of water is defined as 0 degrees and the boiling point of water...
• CEMCivil Emergency Message. A message issued by the National Weather Service in coordination with Federal, state...
• CenterGenerally speaking, the vertical axis of a tropical cyclone, usually defined by the location of minimum wind...
• Center of actionA semi-permanent high or low pressure system that significantly influences the general circulation of the...
• Center of gravityThe unique point where the weighted average of all the mass particles of an object is concentrated, such that...
• Centered differenceA numerical approximation for the derivative of a function at a point, calculated using function values at...
• CentibarA unit of pressure equal to one-hundredth of a bar, or 1000 Pascals (Pa). It is also equivalent to one...
• Centigrade temperature scaleAn older name for the Celsius temperature scale, where the interval between the freezing and boiling points...
• Centimeter burstA solar radio burst in the centimeter wavelength range.
• Centimeter-gram-second systemA system of physical units where the fundamental units of length, mass, and time are the centimeter, gram...
• CentipoiseA unit of dynamic viscosity, equivalent to one-hundredth of a poise. It is a measure of a fluid's resistance...
• Central dense overcastA large, circular, and uniformly cold cloud shield that surrounds the eye of a mature tropical cyclone, as...
• Central forecasting officeA national or principal regional facility responsible for preparing large-scale weather analyses and...
• Central Meridian PassageIn solar-terrestrial terms, the passage of an Active Region or other feature across the longitude meridian...
• Central momentA statistical measure that describes the shape of a probability distribution, calculated as the expected...
• Central pressureThe barometric pressure measured at the middle of a cyclone or anticyclone, a minimum for the cyclone and a...
• Central tendencyA statistical measure that identifies a single value as representative of the center or typical value of a...
• Central waterA distinct water mass found in the upper layers of the ocean, characterized by specific temperature and...
• Centrifugal forceAn apparent force that acts outward on a body moving in a circular path, perceived in a rotating reference...
• Centrifugal instabilityA type of hydrodynamic instability that arises in rotating fluid systems when the angular momentum decreases...
• Centripetal accelerationThe acceleration directed toward the center of curvature that is required to keep an object, such as an air...
• CENTROIDThe center of mass of a storm.
• CeraunographAn instrument that automatically creates a continuous record of lightning discharges occurring within a...
• CeraunometerAn instrument designed to detect and indicate the occurrence of lightning discharges. It responds to the...
• Certainty factorA numerical value, typically ranging from -1 to +1, that expresses the degree of belief or disbelief in a...
• CFCChlorofluorocarbon
• CFPCold Front Passage
• CfsAn abbreviation for cubic feet per second, a unit of volumetric flow rate. It quantifies the volume of fluid...
• Cfs-DayIn hydrologic terms, the volume of water discharged in twenty four hours, with a flow of one cubic foot per...
• CGCloud-to-Ground Lightning
• ChaffSmall, lightweight strips of metallic foil or metallized glass fibers released into the atmosphere...
• Chaff seedingA weather modification technique that releases large numbers of thin metallized fibers, called chaff, into or...
• Chain aggregatesAn ice particle made of several small crystals joined end to end in a line. Chain aggregates have been...
• Chain lengthThe average number of times the propagation cycle of a chemical chain reaction repeats for each initiating...
• Chain reactionA sequence of reactions where the product of one step acts as a reactant for the next, propagating the...
• Chain ruleA fundamental rule of calculus for differentiating a composite function, which is a function of another...
• ChallihoA strong local wind of parts of India that blows in spring, ahead of the summer monsoon, in spells said to...
• ChanceA National Weather Service precipitation descriptor for 30, 40, or 50 percent chance of measurable...
• ChanduyA cool, descending local wind at Guayaquil, a city in Ecuador's Guayas province on the Pacific coast, that...
• Change chartA meteorological map that displays the change in a specific atmospheric variable over a set period of time...
• Change of phaseThe transformation of a substance from one physical state to another, such as from solid to liquid, liquid to...
• Change of stateThe physical process by which a substance transitions from one phase to another, such as solid to liquid...
• ChannelA natural or artificial open conduit that conveys water, typically referring to a river, stream, or gully. In...
• Channel inflowIn hydrologic terms, water, which at any instant, is flowing into the channel system form surface flow...
• Channel leadIn hydrologic terms, an elongated opening in the ice cover caused by a water current.
• Channel routingIn hydrologic terms, the process of determining progressively timing and shape of the flood wave at...
• Channel storageThe volume of water temporarily held within a river channel and its adjacent floodplain during the passage of...
• Channeled high windsIn mountainous areas or in cities with tall buildings, air may be channeled through constricted passages...
• ChannelingThe preferential flow of a fluid through specific pathways within a porous medium or a larger system. In...
• ChannelizationIn hydrologic terms, the modification of a natural river channel; may include deepening, widening, or...
• ChaosA state of disorder and unpredictability in a deterministic system, characterized by extreme sensitivity to...
• Chapman layerA theoretical model describing the vertical distribution of an ionized layer in a planetary atmosphere...
• Chapman mechanismA set of four chemical reactions proposed to explain the formation and destruction of ozone in the Earth's...
• Chappuis bandsA series of absorption bands of ozone in the visible spectrum, specifically between approximately 400 and 700...
• Characteristic equationAn algebraic equation obtained from a linear differential equation or matrix system by substituting an...
• Characteristic lengthA representative length scale used in dimensional analysis to normalize physical equations and simplify the...
• Characteristic of the pressure tendencyA qualitative description of how atmospheric pressure has changed over a recent period, typically the past...
• Characteristic velocityA representative velocity scale used in fluid dynamics to non-dimensionalize equations and analyze the...
• CharacteristicsA method for solving partial differential equations, particularly hyperbolic ones, by transforming them into...
• Characteristic-value problemA mathematical formulation involving a linear operator or matrix where the goal is to find specific vectors...
• Charge separationThe process by which positive and negative electrical charges become spatially separated within a cloud...
• Charles-Gay-Lussac lawA gas law stating that for a fixed amount of gas at constant pressure, the volume is directly proportional to...
• Charnock's relationAn empirical formula that relates the roughness length of the sea surface to the friction velocity of the...
• ChartA graphical representation of meteorological data, typically showing the spatial distribution of atmospheric...
• Chart datumThe reference plane of zero depth used on a nautical or hydrographic chart, to which all soundings and tidal...
• Chart plottingThe manual or automated process of transcribing meteorological observations onto a weather map using...
• CHCChance
• Chemical composition of precipitationThe array of dissolved ions, gases, and particulate matter present in rain, snow, or other forms of...
• Chemical energyThe potential energy stored within the bonds of chemical compounds, which can be released or absorbed during...
• Chemical hygrometerAn instrument that measures atmospheric humidity by observing changes in the physical or electrical...
• ChemisorptionThe process where gas molecules adhere to a solid surface through the formation of a chemical bond, involving...
• Chemistry modelA computer model used in air pollution investigations that simulates chemical and photochemical reactions of...
• ChemosphereA loosely bounded zone high in the atmosphere where photochemistry dominates, reckoned to cover the upper...
• CherguiA hot, dry easterly or southeasterly wind that originates in the Sahara Desert and blows across Morocco. This...
• Chezy equationA hydraulic formula giving the mean velocity of steady, uniform flow in an open channel as a coefficient...
• CHGChange
• CHGSchanges
• ChiliA hot, dry, and dusty southerly wind that blows from the Sahara Desert across Tunisia. This wind is the local...
• Chill factorA measure that quantifies the perceived cooling effect on the human body due to the combined influence of air...
• Chill hourA unit of measure used in agriculture to quantify the cumulative exposure of a dormant plant to cold...
• Chill unitA quantitative measure used in horticulture to account for the chilling requirements of plants, particularly...
• Chilled-mirror hygrometerAn instrument used to measure the dew point or frost point temperature of a gas, which is a direct indicator...
• ChillingThe process of cooling a substance or object to a temperature below that of its surroundings, particularly to...
• Chilling injuryPhysiological damage sustained by plants or plant products when exposed to low, non-freezing temperatures...
• Chimney cloudA tall, narrow cumulus cloud, typically in the tropics, whose vertical extent is much greater than its...
• Chimney plumeA column of smoke, gases, or particulate matter emitted from a chimney or stack, rising into the atmosphere...
• China Coastal CurrentA cold, southward-flowing ocean current that originates in the Yellow Sea and East China Sea, extending along...
• ChinookA warm, dry, downslope wind that occurs on the leeward side of mountain ranges, particularly in western North...
• Chinook archA foehn cloud formation seen as a band of stationary stratiform cloud, such as a flat layer of altostratus...
• Chip logA historical nautical instrument for measuring a vessel's speed through water, providing data for early...
• Chi-square testA statistical hypothesis test used to determine if there is a statistically meaningful difference between...
• Chlorine compoundsA group of chemical species containing chlorine atoms that participate in atmospheric chemical reactions...
• Chlorine dioxideA molecule with the formula OClO and an unpaired electron, formed in the stratosphere mainly when chlorine...
• Chlorine monoxide dimerA molecule formed by the reversible dimerization of two chlorine monoxide (ClO) radicals, typically denoted...
• Chlorine monoxide radicalA highly reactive chemical species with the formula ClO, consisting of one chlorine atom and one oxygen atom...
• Chlorine nitrateA chemical compound with the formula ClONO2, formed in the stratosphere from the reaction of chlorine...
• Chlorine oxidesA family of reactive chemical compounds consisting of chlorine and oxygen atoms, such as chlorine monoxide...
• ChlorinityA measure of the total mass of halide ions, primarily chloride, bromide, and iodide, in a given mass of...
• ChlorofluorocarbonsA class of synthetic organic compounds composed of carbon, chlorine, and fluorine atoms, commonly abbreviated...
• ChloroformA volatile organic compound with the chemical formula CHCl₃, which is a colorless, sweet-smelling liquid at...
• ChlorosityA measure of the concentration of chloride ions in a solution, expressed as the number of grams of chloride...
• ChocolateroA norther of moderate strength on the Gulf coast of Mexico, meaning a northerly wind that follows an outbreak...
• ChopSmall, steep, disordered waves on a water surface raised by local wind, especially when the wind blows...
• Choppy seaA sea surface characterized by short, irregular, and steep waves that break easily. This condition arises...
• Chou lao huA period of unseasonably hot and dry weather that occurs in late summer or early autumn, particularly in...
• ChromosphereA layer of the Sun's atmosphere situated above the photosphere and below the much hotter corona...
• Chromospheric eventsIn solar-terrestrial terms, flares that are just Chromospheric Events without Centimetric Bursts or...
• ChronographAn instrument designed to record the precise time of an event or the duration of an interval. In meteorology...
• Chronometric radiosondeA radiosonde that sends its measurements as time intervals between radio signals rather than as a changing...
• ChronothermometerA thermometer built around a clock mechanism whose running rate varies with temperature, so that temperature...
• ChubascoA violent squall or thunderstorm that occurs along the west coast of Central America, particularly in Mexico...
• ChuradaA severe rain squall of the Mariana Islands, a chain in the western Pacific Ocean that includes Guam...
• CICirrus clouds- High-level clouds (16,000 feet or higher), composed of ice crystals and appearing in the form...
• CierzoA strong, cold, and dry wind that blows from the northwest through the Ebro Valley in Spain. This wind is...
• CIGCeiling- The height of the lowest layer of clouds, when the sky is broken or overcast.
• CINConvective INhibition. A measure of the amount of energy needed in order to initiate convection. Values of...
• CIOChief Information Officer
• Circular depolarization ratioA radar observable that quantifies the ratio of the power received in the cross-polarized channel to the...
• Circular polarizationA type of electromagnetic wave polarization where the electric field vector at a fixed point in space rotates...
• Circular variableA type of variable whose values are angles or directions, such as wind direction or time of day, where the...
• Circular vortexA fluid flow pattern characterized by concentric streamlines or trajectories, where the fluid rotates around...
• CirculationThe net flow of a fluid around a closed curve or circuit, representing the integral of the velocity component...
• Circulation indexA quantitative measure used to characterize the strength or pattern of atmospheric circulation over a...
• Circulation integralA mathematical quantity representing the line integral of the velocity vector around a closed curve in a...
• Circulation patternThe characteristic arrangement of atmospheric flow, typically at a large scale, that persists for a period of...
• Circulation theoremA principle in fluid dynamics, formulated by Vilhelm Bjerknes, that describes the time rate of change of...
• Circulation typeA classification of large-scale atmospheric flow patterns over a specific geographical region, based on...
• Circumhorizontal arcA bright, rainbow-colored halo phenomenon that appears as a large, iridescent band parallel to the horizon...
• Circumpolar whirlA large-scale, persistent cyclonic circulation of air that encircles the Earth's polar regions in the middle...
• Circumscribed haloA halo phenomenon that appears as an elliptical or oval-shaped ring of light that closely surrounds the sun...
• Circumzenithal arcAn optical phenomenon appearing as a brightly colored, arc-shaped halo located directly above the observer...
• Cirque glacierA body of ice that forms in and occupies a cirque, which is a bowl-shaped, amphitheater-like hollow on a...
• CirriformDescribing clouds that are thin, wispy, and composed primarily of ice crystals, characteristic of...
• CirrocumulusA high-level cloud genus made up of small white elements, such as grains or ripples, arranged in groups...
• CirrostratusA high-level cloud type appearing as a transparent, whitish veil that often covers the entire sky, giving it...
• CirrusA genus of high-altitude clouds composed entirely of ice crystals, characterized by their thin, wispy, and...
• Cirrus intortusA cloud variety of cirrus in which the filaments are irregularly curved and appear tangled together in a...
• Cirrus spissatusA dense, opaque form of cirrus cloud that appears gray and often has a fibrous or silky texture. These clouds...
• Cirrus uncinusA species of cirrus cloud characterized by comma-shaped or hook-shaped filaments, often with a tuft or 'head'...
• CisternThe reservoir at the base of a mercury barometer that contains the pool of mercury into which the open end of...
• Cistern barometerA type of mercury barometer where a glass tube, sealed at one end and filled with mercury, is inverted into a...
• CitationA family of twin-engine business jets manufactured by Cessna that are frequently modified for use as...
• Civil dawnThe time of morning at which the sun is 6 degrees below the horizon. At this time, there is enough light for...
• Civil dayA period of 24 hours that begins at midnight local time and ends at the next midnight. This is the standard...
• Civil duskThe time at which the sun is 6 degrees below the horizon in the evening. At this time objects are...
• Civil emergency message(Abbrev. CEM) - A message issued by the National Weather Service in coordination with Federal, state or local...
• Civil twilightThe period of time after sunset or before sunrise when the sun is between 0 and 6 degrees below the horizon...
• CLAn abbreviation used on climate outlook maps issued by CPC to indicate areas where equal chances of...
• ClapotisA non-breaking standing wave pattern formed in a body of water when a progressive surface wave train is...
• Class I areasGeographic areas designated by the Clean Air Act where only a small amount or increment of air quality...
• Class intervalA range of values used to group continuous data into discrete categories for statistical analysis or...
• class-A evaporation panA standardized instrument used to measure the rate of evaporation from a free water surface. It consists of a...
• Classical condensation theoryA theory in which cloud droplets form by condensation only once the air is supersaturated, with relative...
• Clathrate hydrateA crystalline solid compound in which water molecules form a cage-like structure around guest molecules, such...
• Clausius-Clapeyron equationA thermodynamic relationship that describes the phase change between two states of matter, particularly...
• Clay atmometerAn instrument used to measure potential evaporation from a wet, porous ceramic surface, designed to simulate...
• Clayden effectA phenomenon in photography where a photographic emulsion that receives a very brief, high-intensity light...
• CLDCloud- A visible aggregate of minute water droplets or ice particles in the atmosphere above the Earth's...
• Clean airAtmospheric air that contains very low concentrations of pollutants, aerosols, and other particulate matter...
• ClearA sky condition with no cloud, or in United States practice a sky cover of less than one tenth. Automated...
• Clear airA portion of the atmosphere that is free of clouds, precipitation, and other visible hydrometeors such as fog...
• Clear iceA type of aircraft icing that forms when supercooled water droplets freeze slowly upon impact with an...
• Clear line of sightAn unobstructed path between an observer or instrument and a target, allowing for direct visual or...
• Clear skyAn atmospheric condition characterized by the absence of clouds or obscuring phenomena such as fog, haze, or...
• Clear slotWith respect to severe thunderstorms, a local region of clearing skies or reduced cloud cover, indicating an...
• Clear-air echoA radar return signal detected from atmospheric regions that appear visually clear, without visible clouds or...
• Clear-air turbulenceTurbulence encountered in cloud-free regions of the atmosphere, often occurring at high altitudes near the...
• ClearanceThe process by which clouds, fog, or precipitation dissipate or move out of a specific area, leading to...
• ClearingA meteorological process where atmospheric visibility improves due to the dissipation of clouds, fog, or...
• Client agencyAs used in connection with reimbursable National Weather Service (NWS) fire weather services, a public fire...
• CLIMAPA major collaborative research project of the 1970s and 1980s, the name an acronym for Climate: Long-range...
• ClimatThe long-term average weather conditions of a region, encompassing patterns of temperature, precipitation...
• CLIMAT broadcastA scheduled transmission of coded meteorological messages containing monthly climatic data from observing...
• ClimateThe long-term average weather conditions and patterns of a region, encompassing statistical descriptions of...
• Climate analogsGeographic locations that currently experience a climate similar to what another location is projected to...
• Climate anomalyA departure of a climatic variable, such as temperature or precipitation, from its long-term average for a...
• Climate changeA long-term shift in global or regional climate patterns, primarily characterized by changes in average...
• Climate change detectionThe process of demonstrating that climate has changed in a statistically significant way, moving beyond the...
• Climate controlSchemes for deliberately altering or regulating the climate of a region or the whole planet, such as solar...
• Climate diagnostics bulletin(CDB) - The monthly CPC Bulletin reports on the previous months' status of the ocean-atmosphere climate...
• Climate diagnostics center(CDC) - The mission of NOAA's Climate Diagnostics Center is to identify the nature and causes for climate...
• Climate driftThe gradual departure of a climate model's simulated state from observed or expected climatic conditions over...
• Climate fluctuationsVariations in climatic conditions that occur over periods ranging from years to decades or centuries, without...
• Climate impact assessmentsEvaluations of the potential effects of climate change on natural and human systems. These assessments...
• Climate modelA mathematical representation of the Earth's climate system, comprising atmospheric, oceanic, land surface...
• Climate modificationIntentional human intervention to alter the climate system on a regional or global scale. This encompasses...
• Climate monitoringThe systematic and continuous observation of climate variables and indicators over time to detect changes and...
• Climate noiseThe natural, unforced variability within the climate system that can obscure underlying trends or signals of...
• Climate outlookA climate outlook issued by the CPC gives probabilities that conditions, averaged over a specified period...
• Climate periodicityThe recurrence of climatic patterns or events at regular or quasi-regular intervals over time. These cycles...
• Climate predictionThe scientific endeavor of forecasting future climate conditions based on an understanding of Earth's climate...
• Climate prediction centerThis Center is one of several centers under the National Centers for Environmental Prediction (NCEP) part of...
• Climate sensitivityThe equilibrium global mean surface temperature change that results from a doubling of atmospheric carbon...
• Climate servicesThe provision of climate information to assist individuals and organizations in decision-making. This...
• Climate signalA detectable change in a climate variable that is attributable to a specific forcing mechanism, often...
• Climate snow lineThe average elevation above which snow persists on the ground throughout the entire year, representing the...
• Climate systemThe interactive system comprising the atmosphere, oceans, land surface, cryosphere (ice and snow), and...
• Climate variabilityNatural variations in the state of the climate system on all spatial and temporal scales beyond individual...
• Climatic classificationA system for categorizing regions of the Earth based on their characteristic climatic conditions. These...
• Climatic controlA persistent geographical or atmospheric factor that exerts a dominant influence on the climate of a...
• Climatic cycleA recurring pattern of climatic conditions that repeats over a specific period, often driven by natural...
• Climatic diagramA graphical representation that illustrates the average annual cycle of key climatic variables for a specific...
• Climatic discontinuityAn abrupt and lasting change in the mean or variability of a climatic variable, so that the record before and...
• Climatic divideA geographical boundary that separates two distinct climatic regions, characterized by noticeable differences...
• Climatic elementAny one of the atmospheric properties or phenomena that, when considered together, characterize the weather...
• Climatic factorA large-scale, relatively stable geographical or astronomical condition that influences the climate of a...
• Climatic fluctuationA variation in climatic conditions that occurs over periods ranging from years to decades or centuries...
• Climatic indexA numerical value derived from one or more climatic variables that quantifies a specific aspect of climate or...
• Climatic optimumA period in Earth's history characterized by significantly warmer global temperatures compared to preceding...
• Climatic provinceA large geographical area characterized by a relatively uniform climate, distinct from that of adjacent...
• Climatic recordA collection of historical data and proxy evidence that documents past climatic conditions for a specific...
• Climatic regionAn area of the Earth's surface characterized by relatively uniform climatic conditions, distinguished from...
• Climatic riskThe potential for adverse impacts on human or natural systems due to changes in climate, including both...
• Climatic trendA long-term, sustained change in a climatic variable, such as temperature or precipitation, observed over...
• Climatic yearA continuous 12-month period selected for the analysis of meteorological data, often chosen to align with...
• Climatic zoneA broad geographical band encircling the Earth, characterized by similar average temperature and...
• ClimatographyThe descriptive study of climate, focusing on the geographical distribution of climatic elements and their...
• Climatological atlasA collection of maps and charts that visually represent the spatial distribution of climatic elements over a...
• Climatological chartA graphical representation depicting the spatial distribution of a specific climatic element, such as average...
• Climatological dataLong-term records of atmospheric conditions collected over many years at specific locations, including...
• Climatological divisionA geographical area within a larger region, such as a state or country, that is delineated based on...
• Climatological fieldThe spatial distribution of a specific atmospheric variable, such as temperature or pressure, averaged over a...
• Climatological forecastA prediction of future weather conditions based solely on historical climate averages for a specific time of...
• Climatological mean fieldThe average spatial pattern of an atmospheric variable, such as temperature, pressure, or wind, calculated...
• Climatological networkA system of stations on land or sea established to observe and record meteorological elements for...
• Climatological observationA measurement of an atmospheric variable, such as temperature, precipitation, or wind speed, taken at a...
• Climatological outlookAn outlook based upon climatological statistics for a region, abbreviated as CL on seasonal outlook maps. CL...
• Climatological standard normalsLong-term averages of climatological variables, such as temperature and precipitation, calculated over a...
• Climatological stationA designated location equipped with instruments for systematically observing and recording meteorological...
• Climatological station elevationThe vertical distance of a meteorological station's ground level above a standard datum, which is typically...
• Climatological station pressureThe atmospheric pressure measured directly at the elevation of a climatological station. This raw pressure...
• Climatological substationA meteorological observing station that records a more limited set of weather data compared to a principal...
• Climatological summaryA concise report or document that compiles and presents key statistical information about the climate of a...
• Climatological yearA 12-month period selected for compiling and analyzing climate data, structured to keep meteorological...
• ClimatologyThe scientific study of climate, which encompasses the long-term average weather patterns, their causes, and...
• ClimatonomyA branch of climatology that focuses on the physical processes governing the Earth's climate system, often...
• CLIMOClimatology/Climatological
• ClimometerAn instrument that measures angles of inclination; used to measure cloud ceiling heights.
• ClinometerAn instrument used to measure angles of slope or inclination, particularly in meteorological applications for...
• CloA unit of thermal insulation used to quantify the insulating value of clothing or other materials in relation...
• Close pack iceSea ice coverage where the concentration is between 7/10 and 8/10, meaning that 70% to 80% of the sea surface...
• Closed basinA geographical area where surface water runoff does not flow out to an ocean or sea but instead drains into...
• Closed basin lake floodingFlooding that occurs on lakes with either no outlet or a relatively small one. Seasonal increases in rainfall...
• Closed cellsA pattern of mesoscale cellular convection in which cloud-filled cells, often polygonal, are ringed by narrow...
• Closed circulationAn atmospheric flow pattern where streamlines or isobars form complete closed loops around a central pressure...
• Closed drainageA hydrological system where surface water does not have an outlet to the sea, instead collecting in an inland...
• Closed highA high-pressure system characterized by closed isobars or geopotential height contours on a weather map...
• Closed lakeA lake that does not have an outflowing river or stream, meaning its water balance is maintained solely by...
• Closed lowA low-pressure system where at least one isobar or contour line on a constant pressure chart forms a complete...
• Closed systemA thermodynamic system that can exchange energy, but not matter, with its surroundings. In atmospheric...
• Closed weatherWeather conditions at an aerodrome characterized by a low cloud ceiling and poor visibility that are below...
• Closed-cell stratocumulusA type of stratocumulus cloud formation where individual cloud elements are arranged in distinct, often...
• Closure assumptionsSimplifying hypotheses made in atmospheric and climate models to represent complex physical processes that...
• Closure problemThe challenge of representing the effects of unresolved small-scale atmospheric processes on larger, resolved...
• CloudA visible mass of liquid water droplets, frozen ice crystals, or a mixture of both, suspended in the...
• Cloud absorptionThe process by which clouds take in and retain electromagnetic radiation, primarily in the infrared and some...
• Cloud albedoThe fraction of incident solar radiation that is reflected back to space by clouds. This property is...
• Cloud amountThe fraction of the sky covered by clouds, typically expressed in oktas (eighths) or as a percentage. This...
• Cloud attenuationThe reduction in intensity of electromagnetic radiation, such as solar radiation or radar signals, as it...
• Cloud bandAn extensive, elongated formation of clouds that is much longer than it is wide. These formations are readily...
• Cloud bankA well-defined, persistent mass of clouds observed from a distance, typically appearing as a solid wall or...
• Cloud barA narrow, continuous streak of cloud with a long axis, for example a crest cloud forming over a mountain...
• Cloud baseThe underside of a cloud or cloud layer, the height below which the air holds no appreciable cloud particles...
• Cloud cameraA specialized camera used to capture images of clouds and sky conditions, providing visual data for...
• Cloud ceilingThe height of the lowest layer of clouds that covers more than half of the sky, reported in feet above ground...
• Cloud chamberA sealed environment containing a supersaturated vapor of water or alcohol used to visualize the paths of...
• Cloud chartA visual aid or diagram that illustrates and categorizes different types of clouds based on their appearance...
• Cloud classificationThe systematic organization of clouds into distinct categories based on their appearance, altitude, and...
• Cloud clusterA large, organized system of thunderstorms and convective clouds that maintains its identity for a day or...
• Cloud condensation nucleiMicroscopic airborne particles, such as dust, salt, or sulfates, upon which water vapor condenses to form...
• Cloud condensation nuclei counterAn instrument designed to measure the concentration of cloud condensation nuclei (CCN) in the atmosphere. It...
• Cloud coverThe portion of the sky that is concealed by clouds when viewed from a particular location. It is visually...
• Cloud dropA minute liquid water droplet suspended within a cloud, typically with a diameter ranging from a few...
• Cloud dropletA microscopic particle of liquid water, typically between 1 and 100 micrometers in diameter, that constitutes...
• Cloud echoThe radar signal reflected back from a cloud, indicating the presence and characteristics of hydrometeors...
• Cloud electrificationThe process by which electric charges separate and accumulate within clouds, leading to the generation of...
• Cloud elementA single, distinct, and observable component of a larger cloud formation, such as an individual cumulus tower...
• Cloud etageOne of three main altitude ranges in the atmosphere where clouds are typically found, as defined by the World...
• Cloud feedbackThe complex interaction where changes in cloud properties, such as coverage, altitude, or optical depth...
• Cloud flashA discharge of lightning that occurs entirely within a single cloud, or between different clouds, without...
• Cloud formationThe process by which water vapor in the atmosphere condenses or deposits onto microscopic particles, forming...
• Cloud genusOne of the ten primary categories of the international cloud classification, defined by general form and the...
• Cloud heightThe altitude of the base of a cloud or cloud layer above mean sea level or above the Earth's surface. It is a...
• Cloud image animationA sequence of satellite or radar images of clouds displayed rapidly in succession to show their movement and...
• Cloud layerA stratum of clouds with a well-defined base and top, covering a large horizontal area and composed of any...
• Cloud levelA layer of the atmosphere in which particular cloud genera occur, conventionally divided into high, middle...
• Cloud lineA narrow, elongated band of clouds, often indicative of a convergence zone, a frontal boundary, or a line of...
• Cloud microphysicsThe study of the physical processes occurring at the microscopic scale within clouds, involving individual...
• Cloud microstructureThe detailed physical properties of the individual particles within a cloud, including their size...
• Cloud modelA mathematical or numerical representation of the physical processes that govern the formation, evolution...
• Cloud modificationAny intentional human intervention aimed at altering the natural development or properties of clouds...
• Cloud motion vectorA measurement of wind speed and direction derived by tracking the movement of clouds or water vapor features...
• Cloud movementThe direction toward which a cloud is moving
• Cloud nucleusA microscopic airborne particle, either solid or liquid, that serves as a site for water vapor to condense or...
• Cloud optical depthA dimensionless measure of how opaque a cloud is to radiation passing through it, indicating the extent to...
• Cloud particleA microscopic element within a cloud, consisting of either a liquid water droplet or an ice crystal. These...
• Cloud physicsThe branch of atmospheric science that investigates the microphysical processes occurring within clouds...
• Cloud radarA specialized radar system designed to detect and characterize non-precipitating clouds and light...
• Cloud radiative forcingThe net effect of clouds on the Earth's energy balance, determined by their ability to reflect incoming solar...
• Cloud searchlightA powerful light beam projected vertically into the sky to determine the height of the cloud base at night...
• Cloud seedingA weather modification technique that involves introducing substances, such as silver iodide or dry ice, into...
• Cloud shieldA large, contiguous expanse of middle and high-level clouds, primarily cirrostratus and altostratus, that...
• Cloud streetsParallel bands of cumulus clouds that form in the planetary boundary layer, aligned with the mean wind...
• Cloud symbolA standardized graphical representation used on weather maps and charts to denote specific types of clouds or...
• Cloud systemA large, organized collection of clouds that are dynamically and thermodynamically linked, often associated...
• Cloud tagsRagged, detached cloud fragments; fractus or scud.
• Cloud topThe upper boundary of a cloud or cloud layer, the height above which cloud particles are no longer present in...
• Cloud tracerA substance or property within a cloud that can be tracked to infer atmospheric motion or processes. Water...
• Cloud windsWind vectors derived from tracking the movement of identifiable cloud features across a sequence of satellite...
• CloudbowA faint, white or very weakly colored arc observed in clouds, similar to a rainbow but with much broader and...
• CloudburstAn extremely heavy and localized downpour of rain, characterized by a very high rainfall rate over a short...
• Cloud-detection radarA type of radar system specifically designed to detect and characterize clouds, often operating at millimeter...
• Cloud-drop samplerAn instrument designed to collect samples of cloud water droplets for chemical analysis or to measure their...
• Cloud-free line of sightAn unobstructed path through the atmosphere from an observer to a target, without any intervening clouds...
• Cloud-height indicatorAn instrument designed to measure the vertical distance from the ground to the base of a cloud. These...
• Cloud-height measurement methodAny technique employed to determine the vertical distance of a cloud base or top from a reference point...
• Cloud-to-ground flashA discharge of lightning that originates within a thundercloud and terminates on the Earth's surface. This...
• Cloud-top entrainment instabilityA theoretical mechanism that describes the destabilization of a cloud layer due to radiative cooling at its...
• CloudyA sky mostly covered by cloud, which in observing practice denotes a day whose average cloud cover exceeds...
• Cloudy dayA period of daylight hours during which the sky is predominantly covered by clouds, limiting direct sunlight...
• Cloudy skyThe appearance of the atmosphere when a substantial portion of it is obscured by clouds. This condition...
• CLRClear
• CLRGClearing
• Cluster ionsMolecular ions that are surrounded by one or more neutral molecules, which are weakly bound to the central...
• ClutterUnwanted radar echoes originating from stationary objects on the ground, such as buildings, terrain, or...
• Clutter rejectionA signal processing technique used in radar systems to remove unwanted echoes from stationary or slow-moving...
• Cm1. Centimeter
• CMPLTComplete
• CMPLXComplex
• CNIFIn hydrologic terms, Calibration Network Information Files.
• CNTRCenter
• CNTRLCentral
• CNVGConverge
• CNVTVConvective
• CoagulationThe process by which small aerosol particles or cloud droplets collide and stick together, forming larger...
• CoalescenceThe process where two or more cloud droplets or raindrops merge to form a single, larger droplet. This is a...
• Coalescence efficiencyA measure of the probability that two colliding cloud droplets will actually merge to form a single, larger...

1,017 of 10,756 terms in Meteorology and atmospheric science terminology (MLC-0110). Request the full dataset.