Meteorology and atmospheric science terminology · MLC-0110

Meteorology and atmospheric science terms: O (205)

• Oasis effectA localized cooling effect observed in vegetated or moist areas surrounded by drier, hotter environments...
• ObAn abbreviation for a single meteorological observation, representing a set of atmospheric data recorded at a...
• OberwindA local wind phenomenon characterized by a strong, dry, and warm wind that descends from mountain slopes into...
• Objective analysisA mathematical procedure that combines meteorological observations with a prior estimate of the atmospheric...
• Objective forecastA weather prediction derived solely from mathematical and statistical models, without human intervention or...
• Oblique visual rangeThe maximum distance at which an observer can discern an object or light source when looking at an angle...
• Obliquity of the eclipticThe angle between Earth's equatorial plane and the plane of its orbit around the Sun, known as the ecliptic...
• O'Brien cubic polynomialA mathematical function used to represent the vertical profile of turbulent exchange coefficients, such as...
• OBSObservation(s)
• OBSCObscure
• ObscurationA meteorological condition where the sky or horizontal visibility is hidden or reduced by atmospheric...
• Obscuring phenomenaAny atmospheric phenomenon, except clouds, that restricts vertical visibility (e.g., dust, rain, snow, etc.).
• Obscuring phenomenonAny atmospheric condition that reduces visibility by scattering or absorbing light, but is not a form of...
• Observation wellIn hydrologic terms, a non-pumping well used for observing the elevation of the water table or piezometric...
• Observational dayA standardized 24-hour period used for collecting and reporting meteorological data, often beginning and...
• Observational errorThe discrepancy between a measured value and the true value of a physical quantity. This difference arises...
• Observational networkA system of interconnected stations and platforms designed to collect meteorological and atmospheric data...
• ObserverAn individual or automated system responsible for collecting and recording meteorological data at a specific...
• Observing systems simulation experimentA numerical experiment designed to evaluate the potential impact of new or modified observing systems on...
• Obstacle flow signatureA characteristic pattern observed in radar or satellite imagery that indicates the presence of air flowing...
• Obstruction to visionAny phenomenon in the atmosphere, other than precipitation, that reduces horizontal visibility. These...
• Obukhov lengthA characteristic length scale in the atmospheric surface layer that describes the relative contributions of...
• Occluded cycloneA mature extratropical cyclone where the cold front has overtaken the warm front, lifting the warm air mass...
• Occluded depressionAn extratropical cyclone that has undergone the process of occlusion, where the cold front has caught up to...
• Occluded frontA composite front formed when a faster-moving cold front overtakes a warm front, forcing the warm air mass...
• Occluded mesocycloneA mesocyclone in which air from the rear-flank downdraft has completely enveloped the circulation at low...
• OcclusionThe process in the life cycle of an extratropical cyclone where the cold front catches up to and merges with...
• Ocean conveyor beltA global system of deep ocean currents driven by differences in water temperature and salinity, also known as...
• Ocean currentA continuous, directed movement of ocean water generated by forces acting upon the water, such as wind...
• Ocean mixingThe process by which different water masses within the ocean combine, driven by winds, tides, and density...
• Ocean stationA fixed location at sea, occupied by a ship or buoy, equipped to make continuous meteorological and...
• Ocean station vesselA ship specifically equipped and deployed to occupy a designated ocean station for extended periods...
• Ocean Topography ExperimentA joint U.S.-French satellite mission, TOPEX/Poseidon, launched in 1992, designed to measure global sea...
• Ocean wavesUndulations on the surface of the ocean, primarily generated by wind blowing over the water. These waves...
• Ocean weather stationA stationary or semi-stationary platform, such as a ship or buoy, located at a specific point in the ocean to...
• Oceanic meteorologyThe branch of meteorology focused on atmospheric processes and weather phenomena occurring over the oceans...
• OceanicityA measure of the degree to which a region's climate is influenced by the ocean. Areas with high oceanicity...
• OceanographyThe scientific study of all aspects of the Earth's oceans and seas, including their physical, chemical...
• OCFNTOccluded Front - a composite of two fronts, formed as a cold front overtakes a warm or quasi-stationary...
• OCNLOccasional
• OctaA unit of measurement used in meteorology to describe the fraction of the sky covered by clouds. One octa...
• Odd chlorineThe sum of all chlorine-containing chemical species in the stratosphere that can participate in catalytic...
• Odd hydrogenA family of highly reactive, short-lived chemical species in the atmosphere containing an odd number of...
• Odd oxygenThe sum of atomic oxygen (O) and ozone (O3) in the atmosphere. These species are highly reactive and are...
• Odd-oxygen systemThe set of chemical reactions involving atomic oxygen (O) and ozone (O3) that govern the abundance of ozone...
• OEODMThe Office of Equal Opportunity and Diversity Management. Provides a duel role. Advises and assists the...
• OerstedThe unit of magnetic field strength (H-field) in the centimeter-gram-second (CGS) system of units. It is used...
• Off-airwaysDescribing flight operations conducted outside of designated air traffic service routes or controlled...
• Off-center PPI scopeA display mode for a Plan Position Indicator (PPI) radar screen where the radar antenna's location is not at...
• Office of Global ProgramsThe Office of Global Programs (OGP) sponsors focused scientific research, within approximately eleven...
• Offshore breezeA wind that blows from the land towards a body of water. Also known as a land breeze.
• Offshore flowOccurs when air moves from land to sea, and is usually associated with dry weather.
• Offshore watersThat portion of the oceans, gulfs, and seas beyond the coastal waters extending to a specified distance from...
• Offshore waters forecast(OFF) - A National Weather Service marine forecast product for that portion of the oceans, gulfs, and seas...
• Offshore windWind blowing from land towards a body of water, such as a sea or large lake. This wind often develops due to...
• OFSHROffshore
• Ogasawara highA semi-permanent subtropical high-pressure system located over the western North Pacific Ocean, particularly...
• OgiveA pointed, arch-like curve or shape, often referring to the nose cone of a projectile or the leading edge of...
• OHState of Ohio
• OHDOverhead
• Ohmic currentAn electrical current that flows through a medium in direct proportion to the electric field, following Ohm's...
• Oil slickA layer of petroleum or other oily substance floating on the surface of water, often resulting from spills or...
• OktaUsed for the measurement of total cloud cover. One okta of cloud cover is the equivalent of 1/8 of the sky...
• Old snowSnow that has undergone metamorphism, where its original crystal structure has changed due to processes like...
• Old Wives' summerA period of unseasonably warm, dry, and calm weather that occurs in mid-autumn, often after the first frosts...
• OLROutgoing Longwave Radiation
• OmbrometerAn instrument designed to measure the amount of precipitation, typically rainfall, over a specific period. It...
• OmbroscopeA device used to observe and record the duration of rainfall events rather than the intensity or amount. It...
• OmegaA term used to describe vertical motion in the atmosphere. The "omega equation" used in numerical weather...
• Omega equationA diagnostic equation in meteorology that relates vertical motion (omega, or pressure velocity) to...
• Omega highA warm high aloft which has become displaced and is on the polarward side of the jet stream. It frequently...
• Omega sunA rare optical phenomenon observed at sunset or sunrise where the lower limb of the sun appears to be...
• On topA meteorological flight condition where an aircraft is flying above a cloud layer, with clear skies above and...
• One-and-a-half order closureA turbulence closure scheme used in atmospheric models that parameterizes turbulent fluxes based on...
• One-dimensional modelA simplified mathematical representation of atmospheric or oceanic processes where variations are considered...
• One-way entrainment processA process where environmental air is incorporated into a rising buoyant plume or cloud, but there is no...
• Onshore breezeA wind that blows from a body of water towards the land. Also known as a seabreeze
• Onshore flowOccurs when air moves from sea to land, and is usually associated wtih increased moisture.
• Onshore windA wind that blows from the sea or a large body of water towards the land. This type of wind often brings...
• OpacityThe degree to which a substance or medium obstructs the passage of electromagnetic radiation, such as light...
• OpacusA cloud variety describing an extensive sheet or patch of cloud that is sufficiently dense to completely mask...
• OpaqueA condition where a material, such as a cloud, blocks the passage of radiant energy, especially light. Opaque...
• Opaque sky coverThe portion of the sky that is covered by clouds or other obscuring phenomena that are thick enough to hide...
• OPCOcean Prediction Center (Formally the Marine Prediction Center. An NCEP center which produces marine...
• Open cellsA pattern of shallow convection characterized by polygonal or hexagonal shapes of clear air surrounded by...
• Open channel flowThe flow of a fluid in a conduit that has a free surface exposed to the atmosphere, such as a river, canal...
• Open lakes forecast(GLF) - A National Weather Service marine forecast product for the U.S. waters within a Great Lake not...
• Open systemA thermodynamic system that can exchange both matter and energy with its surroundings. In meteorology, many...
• Open-cell cumulusA specific type of cumulus cloud organization characterized by a pattern of clear, cloud-free areas...
• Operational Linescan SystemA scanning radiometer carried aboard Defense Meteorological Satellite Program (DMSP) satellites, designed to...
• Operational numerical modelA computer program that simulates atmospheric processes to produce weather forecasts and analyses, used...
• Operational productsA product that has been fully tested and evaluated and is produced on a regular and ongoing basis.
• Operational weather limitsA set of specific meteorological conditions, defined by a user or regulating body, beyond which a particular...
• Operative temperatureA simplified measure of human thermal comfort that combines the effects of air temperature, mean radiant...
• OperatorA mathematical function or algorithm applied to data fields within a numerical weather prediction model to...
• Opposing windA wind that blows in a direction contrary to the intended path or movement of an object, such as an aircraft...
• OppositionAn astronomical configuration where two celestial bodies, typically a superior planet and the Sun, are on...
• Optical air massThe relative path length of sunlight through the Earth's atmosphere, normalized to the path length when the...
• Optical counterAn instrument that detects and counts airborne particles by measuring the light scattered or absorbed by...
• Optical depthA dimensionless measure of the transparency of a medium, indicating how much light is absorbed or scattered...
• Optical hygrometerAn instrument that measures atmospheric humidity by analyzing the absorption or scattering of light by water...
• Optical imaging probeA specialized instrument used on research aircraft to capture high-resolution images of cloud and...
• Optical massA measure of the path length of sunlight through the Earth's atmosphere, relative to the path length when the...
• Optical meteorA luminous phenomenon observed in the atmosphere that results from the interaction of light with atmospheric...
• Optical particle probeAn instrument designed to detect, count, and size individual atmospheric particles, such as aerosols or cloud...
• Optical pathA measure of the effective distance traveled by electromagnetic radiation through a medium, calculated as the...
• Optical pathlengthThe product of the geometric path length and the refractive index of the medium through which light travels...
• Optical rain gaugeA type of rain gauge that measures precipitation by detecting changes in a light beam caused by falling...
• Optical scattering probeAn instrument that measures the properties of atmospheric particles by analyzing the light scattered by them...
• Optical thicknessA dimensionless quantity that describes the extent to which a medium attenuates electromagnetic radiation due...
• Optical Transient DetectorA space-based sensor designed to detect and locate lightning flashes during both day and night. It was flown...
• Optically homogeneousDescribing a medium in which the refractive index is uniform throughout, meaning light travels at the same...
• Optically smoothDescribing a surface that appears perfectly flat and free of irregularities when viewed with light, meaning...
• Optimal perturbationA small initial disturbance in a meteorological forecast model that grows most rapidly over a specific...
• Optimum interpolationA statistical data assimilation technique used to estimate the value of a meteorological variable at...
• OraA local wind system characterized by a gentle, cool breeze that blows from the lake towards the land during...
• OrbitThe curved path, usually elliptical, that a satellite or other celestial body follows around a larger body...
• Orbit numberA sequential identifier assigned to each complete revolution of a satellite around a celestial body...
• Orbital elementsA set of six parameters that uniquely define the path and position of an object in orbit around another body...
• Orbital motionThe movement of a celestial body or satellite along a curved path, or orbit, around another, more massive...
• Orbital velocityThe speed at which an object travels along its orbit around another celestial body. This velocity is...
• Ordinary cellA single-cell thunderstorm, also known as a pulse storm, characterized by a relatively short lifespan and a...
• Ordinary rayOne of two plane-polarized rays of light created when unpolarized light enters an anisotropic crystal, a...
• OrdinateThe vertical coordinate in a two-dimensional Cartesian coordinate system, representing the value along the...
• Organic acidsA class of organic compounds containing at least one carboxyl group, which are common in the atmosphere...
• Organic nitratesA class of chemical compounds containing a nitrate group bonded to an organic molecule, often formed in the...
• Organic peroxidesA class of organic compounds containing the peroxide functional group (R-O-O-R'), formed in the atmosphere...
• Organized large eddiesCoherent structures of turbulent fluid motion that are larger than the typical small-scale eddies and exhibit...
• OrificeIn hydrologic terms, (1) An opening with closed perimeter, usually sharp edged, and of regular form in a...
• ORIGOriginal
• OrographicRelating to mountains or the effects of their presence on air currents and weather. Orographic lift occurs...
• Orographic cloudA cloud that forms as a result of air being forced to rise over elevated terrain, such as mountains or hills...
• Orographic fogFog that forms when moist air is forced to ascend a topographic barrier, leading to adiabatic cooling and...
• Orographic isobarA line of constant atmospheric pressure that is influenced by the presence of elevated terrain. Unlike...
• Orographic liftingThe process where an air mass is forced to rise as it encounters a topographic barrier, such as a mountain...
• Orographic occlusionA meteorological process where a cold front or cold air mass is forced to ascend over a mountain barrier...
• Orographic precipitationPrecipitation that results from the lifting and cooling of moist air as it flows over mountain ranges or...
• Orographic rainfallRainfall that occurs when moist air is forced to rise over mountains, leading to adiabatic cooling...
• Orographic snow lineThe elevation above which snow persists on mountain slopes throughout the year, influenced by local...
• Orographic stormA weather disturbance characterized by heavy precipitation, typically rain or snow, that is intensified or...
• Orographic upliftSame as Orographic Lifting; occurs when air is forced to rise and cool due to terrain features such as hills...
• Orographic vortexA rotating air mass that forms on the leeward side of a mountain range due to the interaction of airflow with...
• Orographic wavesA wavelike airflow produced over and in the lee of a mountain barrier.
• Orographic wind flowThe modification of wind patterns by mountainous terrain, leading to phenomena such as channeling...
• OrographyThe study of the formation and topography of mountains and hills, particularly their influence on atmospheric...
• OroshiA strong, cold, and dry katabatic wind that descends from mountainous terrain, particularly in Japan. This...
• Orphan anvilSlang for an anvil from a dissipated thunderstorm, below which no other clouds remain.
• OrthogonalDescribing two vectors, functions, or phenomena that are statistically independent or at right angles to each...
• Orthogonal antennasA pair of antennas positioned and oriented so their respective polarization planes are perpendicular to each...
• Orthogonal functionsA set of functions where any two distinct functions in the set are orthogonal to each other over a specified...
• Orthogonal linesLines that intersect at a right angle (90 degrees) to each other. In meteorology, this geometric concept is...
• OscillationA periodic fluctuation in a meteorological or oceanic variable, such as temperature, pressure, or wind speed...
• OscillatorA recurring, large-scale pattern of climate variability characterized by fluctuations between two or more...
• OsmosisThe net movement of a solvent, typically water, across a semipermeable membrane from an area of lower solute...
• Osos windA local, northwesterly sea breeze that funnels through the Los Osos Valley in San Luis Obispo County...
• OstriaA warm, southerly wind that blows across the Adriatic Sea, originating from the south or southeast. This wind...
• OTLKOutlook
• OTROther
• OTRWOtherwise
• Outer atmosphereThe uppermost layers of Earth's atmosphere, primarily comprising the exosphere and parts of the thermosphere...
• Outer convective bandBands in a hurricane that occur in advance of main rain shield and up to 300 miles from the eye of the...
• Outer layerThe outermost stratum of a fluid or gaseous system, often characterized by direct interaction with its...
• Outer vortexA secondary or peripheral rotating air mass that surrounds a more intense central vortex, such as in a...
• OutflowA surge of cool, dense air that spreads horizontally away from the base of a thunderstorm or other convective...
• Outflow boundaryA surface boundary formed by the leading edge of a mass of cool, dense air that flows out from a thunderstorm...
• Outflow channelIn hydrologic terms, a natural stream channel which transports reservoir releases.
• Outflow jetA concentrated, fast-moving current of air spreading horizontally away from the base of a convective system...
• Outgoing longwave radiationElectromagnetic radiation emitted by the Earth and its atmosphere into space, primarily in the infrared...
• OutletIn hydrologic terms, an opening through which water can be freely discharged from a reservoir.
• Outlet discharge structureIn hydrologic terms, protects the downstream end of the outlet pipe from erosion and is often designed to...
• Outlet glacierA stream of ice that flows from an ice cap or ice sheet, often confined by surrounding bedrock valleys. These...
• OutlookA forecast product that provides a broad overview of potential weather hazards for a period extending from...
• OutputThe results or products generated by a meteorological model, instrument, or analysis process. This can...
• OVCOvercast- An official sky cover classification for aviation weather observations, when the sky is completely...
• OvercastA sky condition where the entire celestial dome is covered by a layer of clouds, with no breaks visible. This...
• OverflowThe process where a fluid, such as water or air, exceeds the capacity of its containing boundaries and spills...
• OverhangRadar term indicating a region of high reflectivity at middle and upper levels above an area of weak...
• Overland flowThe movement of water across the land surface as a sheet or in small channels, occurring when the rate of...
• OverlapThe condition where the absorption bands of two or more atmospheric gases coincide at the same wavelengths in...
• OverrunningThe atmospheric process where a warmer, less dense air mass glides upward over a colder, more dense air mass...
• OverseedingThe introduction of an excessive number of ice nuclei into a supercooled cloud during a weather modification...
• Overshooting topA dome-like protrusion of cloud that extends above the main anvil of a severe thunderstorm, indicating a very...
• OverturnThe process of vertical mixing in a body of water or the atmosphere, where denser fluid sinks and less dense...
• OVNGTOvernight
• OVROver
• OVRNOverrun
• OVRNGTOvernight
• Owens dust recorderAn instrument designed to collect and measure airborne particulate matter, specifically dust. It operates by...
• OxidantA chemical compound that readily transfers oxygen atoms or otherwise accepts electrons from another substance...
• OxidationA chemical reaction involving the loss of electrons from an atom, molecule, or ion, which increases its...
• Oxidizing capacity of atmosphereThe ability of the atmosphere to cleanse itself of pollutants and natural emissions through chemical...
• Ox's eyeA small, isolated cloud that appears as a harbinger of an approaching storm, particularly in tropical or...
• OxygenA chemical element with the symbol O and atomic number 8, existing in the atmosphere primarily as a diatomic...
• Oxygen bandA specific range of wavelengths in the electromagnetic spectrum where molecular oxygen (O2) strongly absorbs...
• OyashioA cold subarctic ocean current that flows southward along the eastern coast of Kamchatka and the Kuril...
• Ozmidov scaleA characteristic length scale in stratified fluids that describes the maximum vertical size of turbulent...
• OzoneA molecule composed of three oxygen atoms (O3), found naturally in both the stratosphere and troposphere...
• Ozone action dayA "heads-up" message issued by the Department of Natural Resources (DNR) through the National Weather Service...
• Ozone holeA severe depletion of stratospheric ozone over the Antarctic region, occurring annually during the Southern...
• Ozone isopleth plotA graphical representation used in atmospheric chemistry to show the relationship between ozone concentration...
• Ozone layerA region within the Earth's stratosphere, approximately 15 to 35 kilometers above the surface, characterized...
• Ozone shieldThe region of the stratosphere containing a high concentration of ozone (O3) that absorbs most of the Sun's...
• Ozone-depleting potentialA relative measure of how much a given chemical compound is expected to deplete the stratospheric ozone...
• OzonesondeA specialized balloon-borne instrument package designed to measure the vertical distribution of ozone in the...
• OzonosphereThe atmospheric layer where the concentration of ozone (O3) is greatest, roughly corresponding to the...

205 of 10,816 terms in Meteorology and atmospheric science terminology (MLC-0110). Request the full dataset.