Meteorology and atmospheric science terminology · MLC-0110

Meteorology and atmospheric science terms: C (251)

• C1. Degrees Celsius (°C)
• C AMSContinental Air Mass
• CACloud-to-Air lightning.
• CAACold Air Advection
• 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.
• calibrationIn hydrologic terms, the process of using historical data to estimate parameters in a hydrologic forecast...
• calmA weather condition when no air motion (wind) is detected.
• canyon windA foehn wind that is channeled through a canyon as it descends the lee side of a mountain barrier.
• cap(also called "Lid") A layer of relatively warm air aloft, usually several thousand feet above the ground...
• cap cloudA stationary cloud directly above an isolated mountain peak, with cloud base below the elevation of the peak.
• CAPEConvective Available Potential Energy. A measure of the amount of energy available for convection. CAPE is...
• capillarityIn hydrologic terms,
• capillary fringeIn hydrologic terms, the soil area just above the water table where water can rise up slightly through the...
• Capillary WavesWaves caused by the initial wind stress on the water surface causes what are known as capillary waves. These...
• Capillary ZoneUsed interchangably with Capillary Fringe; the soil area just above the water table where water can rise up...
• CappingA region of negative buoyancy below an existing level of free convection (LFC) where energy must be supplied...
• capping inversionAlternate term for Cap; a layer of relatively warm air aloft, usually several thousand feet above the ground...
• CAPSCenter for Analysis and Prediction of Storms
• carbon dioxideCO_2; a colorless and odorless gas which is the fourth most abundant constituent of dry air.
• Carrington LongitudeA system of fixed longitudes rotating with the sun
• Catalina eddyA Catalina Eddy (coastal eddy) forms when upper level large-scale flow off Point Conception interacts with...
• catchment areaIn hydrologic terms, an area having a common outlet for its surface runoff (also see Drainage Area or Basin...
• CategoricalA National Weather Service precipitation descriptor for a 80, 90, or 100 percent chance of measurable...
• Caution StageThe stage which, when reached by a rising stream, represents the level where appropriate officials (e.g...
• CAVUClear or Scattered Clouds (visibility greater than 10 mi.)
• 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
• ceiling(Abbrev. CIG) - The height of the cloud base for the lowest broken or overcast cloud layer.
• ceilometerA device using a laser or other light source to determine the height of a cloud base. An optical ceilometer...
• cellConvection in the form of a single updraft, downdraft, or updraft/downdraft couplet, typically seen as a...
• CelsiusThe standard scale used to measure temperature in most areas outside the United States. On this scale, the...
• 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...
• Centimeter BurstA solar radio burst in the centimeter wavelength range.
• Central Meridian PassageIn solar-terrestrial terms, the passage of an Active Region or other feature across the longitude meridian...
• CENTROIDThe center of mass of a storm.
• CFCChlorofluorocarbon
• CFPCold Front Passage
• cfsIn hydrologic terms, Cubic Feet per Second - the flow rate or discharge equal to one cubic foot (of water...
• 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
• ChanceA National Weather Service precipitation descriptor for 30, 40, or 50 percent chance of measurable...
• channelIn hydrologic terms, also known as Watercourse; an open conduit either naturally or artificially created...
• 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...
• Channeled High WindsIn mountainous areas or in cities with tall buildings, air may be channeled through constricted passages...
• ChannelizationIn hydrologic terms, the modification of a natural river channel; may include deepening, widening, or...
• CHCChance
• Chemistry ModelA computer model used in air pollution investigations that simulates chemical and photochemical reactions of...
• CHGChange
• CHGSchanges
• chinookThis is a region-specific term used for Foehn Winds in the lee of the Rocky Mountains in the United States...
• chinook archA foehn cloud formation appearing as a bank of altostratus clouds east of the Rocky Mountains, heralding the...
• chlorofluorocarbons(CFCs) - Manufactured substances used as coolants and computer-chip cleaners. When these products break down...
• ChromosphereIn solar-terrestrial terms, the layer of the solar atmosphere above the photosphere and beneath the...
• Chromospheric EventsIn solar-terrestrial terms, flares that are just Chromospheric Events without Centimetric Bursts or...
• CICirrus clouds- High-level clouds (16,000 feet or higher), composed of ice crystals and appearing in the form...
• 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
• circulationThe flow, or movement, of a fluid (e.g., water or air) in or through a given area or volume.
• cirriformHigh altitude ice clouds with a very thin wispy appearance.
• cirrocumulusA cirriform cloud characterized by thin, white patches, each of which is composed of very small granules or...
• cirrostratusA cloud of a class characterized by a composition of ice crystals and often by the production of halo...
• cirrus(abbrev. CI) High-level clouds (16,000 feet or higher), composed of ice crystals and appearing in the form of...
• Civil DawnThe time of morning at which the sun is 6 degrees below the horizon. At this time, there is enough light for...
• 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...
• CLAn abbreviation used on climate outlook maps issued by CPC to indicate areas where equal chances of...
• Class I AreasGeographic areas designated by the Clean Air Act where only a small amount or increment of air quality...
• CLDCloud- A visible aggregate of minute water droplets or ice particles in the atmosphere above the Earth's...
• clear iceA thin coating of ice on terrestrial objects, caused by rain that freezes on impact. The ice is relatively...
• Clear SlotWith respect to severe thunderstorms, a local region of clearing skies or reduced cloud cover, indicating an...
• clear-air turbulence(CAT) - In aviation, sudden severe turbulence occurring in cloudless regions that causes violent buffeting of...
• Client AgencyAs used in connection with reimbursable National Weather Service (NWS) fire weather services, a public fire...
• climateThe composite or generally prevailing weather conditions of a region, throughout the year, averaged over a...
• climate changeA non-random change in climate that is measured over several decades or longer. The change may be due to...
• 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 modelMathematical model for quantitatively describing, simulating, and analyzing the interactions between the...
• Climate OutlookA climate outlook issued by the CPC gives probabilities that conditions, averaged over a specified period...
• Climate Prediction CenterThis Center is one of several centers under the National Centers for Environmental Prediction (NCEP) part of...
• climate systemThe system consisting of the atmosphere (gases), hydrosphere (water), lithosphere (solid rocky part of the...
• Climatological OutlookAn outlook based upon climatological statistics for a region, abbreviated as CL on seasonal outlook maps. CL...
• ClimatologyThe science that deals with the phenomena of climates or climatic conditions.
• CLIMOClimatology/Climatological
• ClimometerAn instrument that measures angles of inclination; used to measure cloud ceiling heights.
• closed basinA basin draining to some depression or pond within its area, from which water is lost only by evaporation or...
• Closed Basin Lake FloodingFlooding that occurs on lakes with either no outlet or a relatively small one. Seasonal increases in rainfall...
• closed lowA low pressure area with a distinct center of cyclonic circulation which can be completely encircled by one...
• cloud(abbrev. CLD) A visible aggregate of minute water droplets or ice particles in the atmosphere above the...
• cloud ceilingSame as Ceiling; the height of the cloud base for the lowest broken or overcast cloud layer.
• cloud condensation nucleiSmall particles in the air on which water vapor condenses and forms cloud droplets.
• cloud layerAn array of clouds whose bases are at approximately the same level.
• Cloud MovementThe direction toward which a cloud is moving
• cloud streetsRows of cumulus or cumulus-type clouds aligned parallel to the low-level flow. Cloud streets sometimes can be...
• Cloud TagsRagged, detached cloud fragments; fractus or scud.
• cloudyWhen 7/8ths or more of the sky is covered by clouds.
• CLRClear
• CLRGClearing
• clutterRadar echoes that interfere with observation of desired signals on the radar display.
• cm1. Centimeter
• CMPLTComplete
• CMPLXComplex
• CNIFIn hydrologic terms, Calibration Network Information Files.
• CNTRCenter
• CNTRLCentral
• CNVGConverge
• CNVTVConvective
• coalescenceThe process by which water droplets in a cloud collide and come together to form raindrops.
• Coastal FloodingFlooding which occurs when water is driven onto land from an adjacent body of water. This generally occurs...
• Coastal WatersIncludes the area from a line approximating the mean high water along the mainland or island as far out as...
• Coastal Waters ForecastThe marine forecast for areas, including bays, harbors, and sounds, from a line approximating the mean high...
• Coastal/Lakeshore Flood AdvisoryMinor flooding is possible (i.e., over and above normal high tide levels. Coastal/Lakeshore Flood Advisories...
• Coastal/Lakeshore Flood WarningFlooding that will pose a serious threat to life and property is occurring, imminent or highly likely...
• Coastal/Lakeshore Flood WatchFlooding with significant impacts is possible. Coastal/Lakeshore Flood Watches are issued using the...
• Coastal/Lakeshore Flooding(i) (Oceanic) Coastal Flooding is the inundation of land areas caused by sea waters over and above normal...
• COEIn hydrologic terms, Corps of Engineers.
• coherent radarA radar that utilizes both signal phase and amplitude to determine target characteristics.
• Cold AdvectionTransport of cold air into a region by horizontal winds.
• Cold Air AvalancheDownslope flow pulsations that occur at more or less regular intervals as cold air builds up on a peak or...
• Cold Air DamA shallow cold air mass which is carried up the slope of a mountain barrier, but with insufficient strength...
• Cold Air DammingThe phenomenon in which a low-level cold air mass is trapped topographically. Often, this cold air is...
• Cold Air FunnelA funnel cloud or (rarely) a small, relatively weak tornado that can develop from a small shower or...
• cold frontA zone separating two air masses, of which the cooler, denser mass is advancing and replacing the warmer.
• Cold OcclusionA frontal zone formed when a cold front overtakes a warm front and, being colder than the air ahead of the...
• cold poolA region of relatively cold air, represented on a weather map analysis as a relative minimum in temperature...
• Cold Weather AdvisoryThis product is issued for dangerously cold temperatures or wind chill values that are not expected to reach...
• collar cloudA generally circular ring of cloud that may be observed on rare occasions surrounding the upper part of a...
• collection efficiencyThe fraction of droplets approaching a surface that actually deposit on that surface.
• Colorado lowA low pressure storm system that forms in winter in southeastern Colorado or northeastern New Mexico and...
• Columnar IceIn hydrologic terms, ice consisting of columnar shaped grain. The ordinary black ice is usually...
• Combined SeasGenerally referred to as SEAS. Used to describe the combination or interaction of wind waves and swells in...
• Comma CloudA synoptic scale cloud pattern with a characteristic comma-like shape, often seen on satellite photographs...
• Comma EchoA thunderstorm radar echo which has a comma-like shape. It often appears during latter stages in the life...
• Complex Gale/StormIn the high seas and offshore forecasts, an area for which gale/storm force winds are forecast or are...
• complex terrainTypically used to refer to mountainous terrain. In general usage, it may also refer to coastal regions and...
• CompositeAn average that is calculated according to specific criteria. For example, one might want a composite for the...
• Composite HydrographA stream discharge hydrograph which includes base flow, or one which corresponds to a net rain storm of...
• Comprehensive Flare IndexIn solar-terrestrial terms, the indicative of solar flare importance.
• Concentric RingsThese are common in the most intense hurricanes. They usually mark the end the period of intensification...
• CONDCondition
• condensationIn general, the physical process by which a vapor becomes a liquid or solid; the opposite of evaporation...
• Condensation FunnelA funnel-shaped cloud associated with rotation and consisting of condensed water droplets (as opposed to...
• Conditionally Unstable AirAn atmospheric condition that exists when the environmental lapse rate is less than the dry adiabatic lapse...
• conductionFlow of heat in response to a temperature gradient within an object or between objects that are in physical...
• cone of depressionIn hydrologic terms, the depression, roughly conical in shape, produced in a water table, or other...
• Cone of InfluenceSame as Cone of Depression; in hydrologic terms, the depression, roughly conical in shape, produced in a...
• Confined Ground WaterIn hydrologic terms, ground water held under an aquiclude or an aquifuge, called artesian if the pressure is...
• confluenceA pattern of wind flow in which air flows inward toward an axis oriented parallel to the general direction of...
• congestus(or Cumulus Congestus) - same as towering cumulus.
• Congressional Organic Act of 1890The act that assigned the responsibility of river and floor forecasting for the benefit of the general...
• coningWith regards to wildfires, pattern of plume dispersion in a neutral atmosphere, in which the plume attains...
• Conjugate PointsTwo points on the earth's surface, at opposite ends of a geomagnetic field line
• Conservation StorageIn hydrologic terms, storage of water for later release for usual purposes such as municipal water supply...
• Consolidated Ice CoverIn hydrologic terms, ice cover formed by the packing and freezing together of floes, brash ice and other...
• constant-pressure chartAlternate term for Isobaric Chart; a weather map representing conditions on a surface of equal atmospheric...
• CONTContinue/Continuously
• ContentsIn hydrologic terms, the volume of water in a reservoir. Unless otherwise indicated reservoir content is...
• Continental Air MassA dry air mass originating over a large land area. Contrast with tropical air mass.
• continental shelfThe zone bordering a continent and extending to a depth, usually around 100 FM, from which there is a steep...
• Continuum StormIn solar-terrestrial terms, general term for solar noise lasting for hours and sometimes days.
• Control PointsIn hydrologic terms, small monuments securely embedded in the surface of the dam. Any movement of the...
• CONTScontinues
• CONUSContinental United States
• convectionGenerally, transport of heat and moisture by the movement of a fluid.
• convective boundary layerThe unstable boundary layer that forms at the surface and grows upward through the day as the ground is...
• Convective CloudsThe vertically developed family of clouds are cumulus and cumulonimbus. The height of their bases range from...
• convective condensation level(abbrev. CCL)- The level in the atmosphere to which an air parcel, if heated from below, will rise dry...
• Convective inhibition(CIN or B-) - A numerical measure of the strength of "capping," typically used to assess thunderstorm...
• Convective Outlook(sometimes called AC) - A forecast containing the area(s) of expected thunderstorm occurrence and expected...
• Convective OverdevelopmentConvection that covers the sky with clouds, thereby cutting off the sunshine that produces convection.
• convective temperatureThe approximate temperature that the air near the ground must warm to in order for surface-based convection...
• convergenceA contraction of a vector field; the opposite of divergence. Convergence in a horizontal wind field indicates...
• Conveyance LossIn hydrologic terms, the loss of water from a conduit due to leakage, seepage, evaporation, or...
• Cooling Degree Days(Abbrev. CDD) - A form of Degree Day used to estimate energy requirements for air conditioning or...
• cooperative observerAn individual (or institution) who takes precipitation and temperature observations-and in some cases other...
• Coordinated Universal TimeBy international agreement, the local time at the prime meridian, which passes through Greenwich, England...
• CORCorrection
• Core Punch[Slang], a penetration by a vehicle into the heavy precipitation core of a thunderstorm.
• Coriolis forceA fictitious force used to account for the apparent deflection of a body in motion with respect to the earth...
• Corn Snow IceIn hydrologic terms, rotten granular ice.
• Corner EffectsA small-scale convergence effect that can be quite severe. It occurs around steep islands and headlands.
• Corona1. The outermost layer of the solar atmosphere, characterized by low densities (< 1.0x10^9/cc) and high...
• Coronal holeIn solar-terrestrial terms, an extended region of the corona, exceptionally low in density and associated...
• Coronal Rain(Abbrev. CRN) In solar-terrestrial terms, material condensing in the corona and appearing to rain down into...
• Coronal TransientsIn solar-terrestrial terms, a general term for short-time-scale changes in the corona, but principally used...
• Correlated ShearAn output of the mesocyclone detection algorithm indicating a 3-dimensional shear region (i.e. vertically...
• correlationA measure of similarity between variables of functions.
• Cosmic RayAn extremely energetic (relativistic) charged particle.
• County Warning and Forecast AreaThe group of counties for which a National Weather Service Forecast Office is responsible for issuing...
• County Warning AreaThe group of counties for which a National Weather Service Forecast Office is responsible for issuing...
• Coupled Atmosphere-Ocean ModelSame as Coupled Model; in the context of climate modeling this usually refers to a numerical model which...
• coupled modelIn the context of climate modeling this usually refers to a numerical model which simulates both atmospheric...
• CoupletAdjacent maxima of radial velocities of opposite signs.
• CPCClimate Prediction Center
• CreekA small stream of water which serves as the natural drainage course for a drainage basin of nominal, or small...
• crepuscular raysThe alternating bands of light and dark (rays and shadows) seen at the earth's surface when the sun shines...
• CrestHighest point in a wave.
• Crest GageA gage used to obtain a record of flood crests at sites where recording gages are installed.
• Crest WidthIn hydrologic terms, the thickness or width of a dam at the level of the crest (top) of the dam. The term...
• critical depthIn hydrologic terms, The depth of water flowing in an open channel or conduit, partially filled...
• critical flowIn hydrologic terms, a condition of flow where the mean velocity is at one of the critical values; ordinarily...
• Critical Rainfall Probability(Abbrev. CRP) - In hydrologic terms, the Probability that the actual precipitation during a rainfall event...
• CRNCoronal Rain - In solar-terrestrial terms, material condensing in the corona and appearing to rain down into...
• CrochetIn solar-terrestrial terms, a sudden deviation in the sunlit geomagnetic field (H component; see geomagnetic...
• crop moisture indexIn 1968, Palmer developed the index to assess short-term crop water conditions and needs across major...
• Cross-Valley Wind SystemA thermally driven wind that blows during daytime across the axis of a valley toward the heated sidewall.
• Crown FireA fire where flames travel from tree to tree at the level of the tree's crown or top.
• CrowningMovement of a fire from the understory into the crown of a forest canopy.
• CRPCritical Rainfall Probability - in hydrologic terms, the probability that a given rainfall will cause a...
• CRSConsole Replacement System for NOAA Weather Radio
• cryologyThe science of the physical aspects of snow, ice, hail, and sleet and other forms of water produced by...
• CSDRBLConsiderable
• CSIConditional Symmetric Instability
• CSTCentral Standard Time
• CSTLcoastal
• CTYcity
• CUCumulus clouds - Detached clouds, generally dense and with sharp outlines, showing vertical development in...
• Cubic Feet per Second(Abbrev. CFP) - In hydrologic terms, a unit expressing rates of discharge. One cubic foot per second is equal...
• CUFRACumulus Fractus
• cumuliformDescriptive of all clouds with vertical development in the form of rising mounds, domes, or towers
• Cumuliform AnvilA thunderstorm anvil with visual characteristics resembling cumulus-type clouds (rather than the more typical...
• cumulus(Abbrev. CU) - detached clouds, generally dense and with sharp outlines, showing vertical development in the...
• Cumulus BuildupsClouds which develop vertically due to unstable air. Characterized by their cauliflower-like or tower-like...
• cumulus congestusA large, towering cumulus cloud with great vertical development, usually with a cauliflower-like appearance...
• currentA horizontal movement of water. Currents may be classified as tidal and nontidal. Tidal currents are caused...
• current meterIn hydrologic terms, device used to measure the water velocity or current in a river.
• Curtain DrainIn hydrologic terms, a drain constructed at the upper end of the area to be drained, to intercept surface or...
• CutoffIn hydrologic terms, from passing through a dam’s foundation material. An impervious construction or material...
• cutoff lowA closed upper-level low which has become completely displaced (cut off) from basic westerly current, and...
• CVRCover
• CWACounty Warning Area
• CWFACounty Warning and Forecast Area
• CYCCyclone- A large-scale circulation of winds around a central region of low atmospheric pressure...
• CYCLGNCyclogenesis - The formation or intensification of a cyclone or low-pressure storm system.
• Cyclic StormA thunderstorm that undergoes cycles of intensification and weakening (pulses) while maintaining its...
• cyclogenesis(Abbrev. CYCLGN) - The formation or intensification of a cyclone or low-pressure storm system.
• cyclone(abbrev. CYC) - A large-scale circulation of winds around a central region of low atmospheric pressure...
• cyclonic circulationCirculation (or rotation) which is in the same sense as the Earth's rotation, i.e., counterclockwise (in the...

251 of 3,164 terms in Meteorology and atmospheric science terminology (MLC-0110). Request the full dataset.