Meteorology and atmospheric science terminology · MLC-0110

Meteorology and atmospheric science terms: S (1,280)

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• S1) South or 2) Snow
• SABSatellite Analysis Branch, part of NESDIS NESDIS: National Environmental Satellite, Data and Information...
• Sacramento Soil Moisture Accounting ModelA continuous soil moisture accounting model with spatially lumped parameters that simulates runoff within a...
• Saddle-backA gap of clear air that lies between the tall towers of a pair of adjacent cumulonimbus or cumulus congestus...
• SafetyNETInmarsat-C SafetyNET is an internationally adopted, automated satellite system for promulgating weather...
• Saffir-Simpson hurricane scaleA classification system for hurricanes in the Atlantic and Northeast Pacific basins, categorizing them based...
• Saffir-Simpson Hurricane Wind ScaleThe Saffir-Simpson Hurricane Wind Scale is a 1 to 5 categorization based on the hurricane's intensity at the...
• Saharan air layerA mass of very dry, dusty air that forms over the Sahara Desert and moves westward over the Atlantic Ocean...
• SahelA semi-arid transitional zone in Africa situated between the Sahara Desert to the north and the more humid...
• SalinityThe total concentration of dissolved salts in a body of water, primarily sodium chloride, but also including...
• Salinity bridgeAn instrument used to measure the electrical conductivity of water, which is then correlated to its salinity...
• SalinometerAn instrument designed to measure the salinity of a solution, primarily seawater. It operates by determining...
• Salt contentThe total mass of dissolved inorganic salts present in a given volume or mass of water. This measurement is a...
• Salt fingeringA form of double-diffusive convection that occurs in stratified fluids where a warmer, saltier layer overlies...
• Salt hazeAn atmospheric phenomenon characterized by reduced visibility due to the presence of numerous microscopic...
• Salt lensA lens-shaped body of unusually salty water embedded in water of lower salinity, formed when a patch of dense...
• Salt seedingA weather modification technique that involves introducing hygroscopic salt particles into clouds to enhance...
• Saltwater intrusionThe encroachment of saline water into a body of fresh water, particularly in coastal aquifers and estuaries...
• SAME(Specific Area Message Encoding) - A tone alert system which allows NOAA Weather Radio receivers equipped...
• SAMEXStorm and Mesoscale Ensemble Experiment
• SampleA small, representative portion of a larger body of material or data collected for analysis. In atmospheric...
• Sampling frequencyThe rate at which sensor data is read or sampled.
• San Marco satellitesA series of Italian scientific satellites launched between 1964 and 1988, most of them from the San Marco...
• Sand hazeA suspension of fine sand particles in the atmosphere, reducing visibility over a wide area. This phenomenon...
• Sand snowSnow that has fallen at very low temperatures, of the order of minus 25 degrees Celsius, and that lies on the...
• Sand wallThe leading edge of a large, intense dust storm, known as a haboob, which appears as a towering, opaque wall...
• Sand whirlA rapidly rotating column of air that lifts loose sand and dust from the ground, forming a visible vortex...
• SandstormA meteorological phenomenon characterized by strong winds lifting large quantities of sand and dust from dry...
• Santa AnaA strong, dry, and warm katabatic wind that descends from the elevated desert plateaus of the Great Basin...
• Santa Ana windIn southern California, a weather condition in which strong, hot, dust-bearing winds descend to the Pacific...
• Santa Rosa stormA meteorological phenomenon characterized by strong winds and heavy rainfall that affects the Río de la Plata...
• SàrcaA cold, katabatic wind that blows on Lake Garda in northern Italy. This wind originates in the Sarca valley...
• Sargasso SeaA region of the North Atlantic Ocean characterized by its calm, clear waters and an abundance of Sargassum...
• SastrugaAn irregular ridge or groove formed on a snow surface by wind erosion and deposition. These features are...
• SastrugiIrregular ridges or grooves sculpted on a snow surface by the wind, resulting from differential erosion and...
• SAT1. Satellite (imagery)
• SatelliteAn artificial object placed into orbit around the Earth or another celestial body for scientific...
• Satellite hydrology programA NOHRSC program that uses satellite data to generate areal extent of snow cover data over large areas of the...
• Satellite Infrared SpectrometerAn early satellite-borne instrument designed to measure infrared radiation emitted by the Earth's surface and...
• Satellite meteorologyThe branch of meteorology that uses data collected by Earth-orbiting satellites to observe, analyze, and...
• Satellite pour l'Observation de la TerreA series of Earth observation satellites developed by France, often referred to by its acronym SPOT. These...
• Satellite soundingThe technique of remotely sensing vertical profiles of atmospheric properties, such as temperature and...
• Satellite zenith angleThe angle between the local vertical direction at a point on the Earth's surface and the line of sight to an...
• SATLSatellite
• Saturated soilSoil in which all pore spaces between soil particles are completely filled with water. This condition occurs...
• Saturated zoneThe area beneath the Earth's surface where all pore spaces in the soil or rock are completely filled with...
• SaturationThe state where the air holds the maximum possible amount of water vapor at a given temperature and pressure...
• Saturation deficitThe difference between the amount of water vapor required to saturate the air at a given temperature and the...
• Saturation equivalent potential temperatureThe equivalent potential temperature a parcel would have if it were saturated at its present temperature and...
• Saturation levelThe altitude at which a rising parcel of unsaturated air becomes saturated, typically due to adiabatic...
• Saturation mixing ratioThe maximum mass of water vapor that can exist in a unit mass of dry air at a given temperature and pressure...
• Saturation pointThe specific temperature and pressure at which air can hold no more water vapor, meaning it is fully...
• Saturation pressureThe partial pressure exerted by water vapor when the air is saturated at a given temperature. This pressure...
• Saturation signalA condition in a sensor or detector where the input signal exceeds its maximum measurable range, leading to a...
• Saturation specific humidityThe maximum amount of water vapor that a parcel of air can hold at a given temperature and pressure...
• Saturation static energyA thermodynamic quantity representing the total energy of a parcel of air if it were saturated with water...
• Saturation temperatureThe temperature at which a substance, typically water vapor in the atmosphere, begins to condense into a...
• Saturation vapor pressureThe maximum partial pressure that water vapor can exert in a mixture of gases, such as the atmosphere, at a...
• SavannaA grassland ecosystem characterized by scattered trees and shrubs, typically found in tropical or subtropical...
• Savart polariscopeAn instrument for detecting polarized light, in particular skylight, made of two equal birefringent plates...
• SAWRSSupplementary Aviation Reporting Station - the SAWRS program addresses the concerns of users who depend on...
• Sawtooth waveA type of non-sinusoidal waveform characterized by a linear rise or fall followed by an abrupt return to the...
• S-band radarThese were in use as network radars in the National Weather Service prior to the installation of the WSR 88-D...
• SBCAPESurface Based CAPE; CAPE calculated using a Surface based parcel.
• SBL strengthA measure of the stability or intensity of the Stable Boundary Layer, often quantified by the magnitude of...
• SBNDSouthbound
• SBSDSubside
• SCStratocumulus
• SCASmall Craft Advisory
• ScalarA physical quantity that is fully described by its magnitude alone, without any associated direction...
• Scalar productA mathematical operation between two vectors that results in a scalar quantity, also known as the dot...
• ScaleA characteristic dimension or magnitude used to classify atmospheric phenomena based on their spatial or...
• Scale analysisA method used to simplify the governing equations of atmospheric or oceanic motion by estimating the orders...
• Scale factorThe dimensionless ratio of a map projection's actual scale at a given point or along a given line to its...
• Scale heightThe vertical distance over which an atmospheric property, such as pressure or density, decreases by a factor...
• Scan lineA single row of data collected by a scanning instrument as it sweeps across a target area. In remote sensing...
• ScannerAn instrument that systematically samples a region or object by moving a sensor across it to collect data...
• ScanningThe process of systematically moving a sensor or detector across a target area to collect data over a spatial...
• Scanning Microwave SpectrometerA satellite-borne instrument that measures thermal microwave radiation emitted from the Earth's surface and...
• Scanning Multifrequency Microwave RadiometerA satellite sensor that passively measures microwave radiation emitted and scattered by the Earth's surface...
• Scanning radiometerA type of radiometer that collects electromagnetic radiation by systematically sweeping its field of view...
• ScatterThe process by which electromagnetic radiation, such as sunlight or radar waves, is redirected in multiple...
• Scatter angleThe angle between the direction of an incident electromagnetic wave and the direction of the scattered wave...
• Scatter diagramA graphical representation that displays the relationship between two variables for a set of data points...
• Scatter propagationThe transmission of radio waves beyond the line of sight by means of scattering from irregularities in the...
• ScatteredDescribing electromagnetic radiation or particles that have been deflected from their original path after...
• Scattered powerThe portion of incident electromagnetic radiation that is redirected by particles in a medium, such as the...
• Scattered radiationElectromagnetic radiation that has been deflected from its original direction of propagation after...
• ScatteringThe process by which electromagnetic radiation or particles are deflected from their original path due to...
• Scattering area coefficientA measure of the total scattering effect of a collection of particles per unit volume of air. It represents...
• Scattering coefficientA quantitative measure of the amount of radiation scattered by a medium per unit path length. It describes...
• Scattering cross sectionA hypothetical area that represents the effective target size of a particle for scattering incident...
• Scattering efficiency factorA dimensionless quantity that describes how effectively a particle scatters incident electromagnetic...
• Scattering functionA mathematical description of the angular distribution of scattered radiation from a particle or a volume of...
• Scattering matrixA mathematical construct, also known as the Mueller matrix, that relates the Stokes parameters of an incident...
• ScatterometerA type of radar instrument that measures the backscattered microwave radiation from the Earth's surface. It...
• Scavenging by precipitationThe process by which atmospheric aerosols, gases, and other pollutants are removed from the atmosphere by...
• Scavenging coefficientA parameter used in atmospheric chemistry models to quantify the rate at which aerosols or trace gases are...
• SchlernwindA local mountain wind that flows down from the Schlern massif in the Dolomites, typically occurring during...
• SchlierenOptical inhomogeneities in a transparent medium that are not visible to the naked eye but can be detected by...
• Schmidt numberA dimensionless quantity that relates the momentum diffusivity (kinematic viscosity) to the mass diffusivity...
• Schuman-Ludlam limitThe accretion rate, set by the cloud's liquid water content and the hailstone's size and speed, at which an...
• Schumann resonanceA set of global electromagnetic resonances in the Earth-ionosphere cavity, excited by lightning discharges...
• ScintillationThe rapid, random fluctuations in the intensity, phase, or angle of arrival of electromagnetic radiation as...
• ScintillometerAn instrument used to measure atmospheric turbulence by observing the scintillation of light or microwave...
• Scofield-Oliver techniqueA method used to estimate rainfall rates and amounts from satellite infrared imagery, particularly for...
• ScopeThe cathode-ray tube display unit of a weather radar system that visually presents information about detected...
• Scorer parameterA quantity, written l squared, equal to the squared Brunt-Vaisala frequency divided by the squared wind...
• Scotch mistA fine, persistent drizzle or light rain, often accompanied by fog or low cloud, that is characteristic of...
• Scotopic visionThe type of vision that occurs in low light conditions, primarily mediated by the rod photoreceptors in the...
• ScreenA protective enclosure designed to shield meteorological instruments, such as thermometers and hygrometers...
• Screened panAn evaporation pan that is covered with a mesh screen to reduce the effects of direct solar radiation and...
• Screening layerA thin layer in the atmosphere or ionosphere where electric fields are significantly reduced or 'screened'...
• ScrubberAn air pollution control device that removes particulate matter and gases from industrial exhaust streams. It...
• SCTScattered
• ScudRagged, detached fragments of cloud that appear below a main cloud base, often associated with precipitation...
• S-curveA graphical representation characterized by an initial slow growth phase, followed by a period of rapid...
• S-curve methodA hydrological technique used to derive a unit hydrograph for a specific duration from a unit hydrograph of a...
• SESoutheast
• SeaThe interconnected body of saltwater covering most of the Earth's surface, a primary driver of global weather...
• Sea breezeA local wind system that develops near coastlines due to differential heating between land and sea. During...
• Sea breeze convergence zoneThe zone at the leading edge of a sea breeze where winds converge. The incoming air rises in this zone, often...
• Sea clutterUnwanted radar echoes returned from ocean waves, particularly in rough sea conditions. These echoes can...
• Sea fogAn advection fog that forms when warm, moist air moves over a cooler body of water, causing the air to cool...
• Sea iceFrozen seawater that forms, grows, and melts in the ocean, distinct from icebergs which are calved from...
• Sea levelThe average height of the ocean's surface, used as a reference point for measuring elevation and depth on...
• Sea level measurementsObservations of the height of the ocean surface relative to a fixed reference, made by coastal tide gauges...
• Sea level pressureThe atmospheric pressure at a given location, adjusted to what it would be if that location were at mean sea...
• Sea level riseAn increase in the average height of the ocean surface over time, primarily driven by thermal expansion of...
• Sea smokeA type of fog that forms when very cold air moves over much warmer water. The warm water evaporates rapidly...
• Sea stateThe general condition of the ocean surface with respect to waves, swell, and wind. It describes the height...
• Sea surface temperatureThe temperature of the upper ocean, measured within roughly the top few meters of water. Ships, moored buoys...
• Sea surface temperatures, see Sea surface temperature
• Sea turnA local change in wind direction near coastal areas, where the prevailing wind shifts from an offshore to an...
• Sea-breeze frontThe leading edge of the cooler, denser air mass associated with a sea breeze as it penetrates inland. This...
• Search radarA radar that scans a large volume of airspace or sea surface to detect targets and give their approximate...
• Search spaceThe set of all possible solutions or parameter combinations that an algorithm explores to find an optimal...
• SearchlightAn instrument used in early methods of determining cloud base height at night, consisting of a powerful light...
• SearchlightingA radar operating technique in which the antenna beam is held steady on a chosen target or direction instead...
• Seas, see Sea
• Sea-salt nucleusA type of hygroscopic aerosol particle formed when bubbles burst at the ocean surface, ejecting tiny droplets...
• SeasatThe first Earth-orbiting satellite dedicated to oceanographic research, launched by NASA in 1978. It carried...
• Seasat'' surface windSurface wind measurements derived from data collected by the Seasat satellite, which operated in 1978. The...
• SeasonA division of the year marked by distinct changes in weather, ecology, and hours of daylight, primarily...
• SeaStarA satellite built and owned by Orbital Sciences Corporation, launched on a Pegasus rocket in August 1997...
• Sea-Viewing Wide Field-of-View SensorAn ocean color instrument flown on satellites, designed to measure the color of the ocean by detecting...
• SeawaterWater found in oceans and seas, characterized by its dissolved salt content, primarily sodium chloride. Its...
• Seawater intrusionThe landward migration of seawater into coastal freshwater systems, including surface water bodies and...
• Seawater thermometerA specialized thermometer designed for measuring the temperature of ocean water at or below the surface...
• Secchi diskA simple, flat, circular disk, typically 30 centimeters in diameter, with alternating black and white...
• SeclusionA stage of cyclone development in the Shapiro-Keyser model in which the bent-back warm front wraps around the...
• Second law of thermodynamicsA fundamental principle stating that the total entropy of an isolated system can only increase over time, or...
• Second SummerA period of unseasonably warm and dry weather that occurs in late autumn, following the first onset of...
• Secondary ambient air quality standardsAir quality standards designed to protect human welfare, including the effects on vegetation and fauna...
• Secondary bandsSmall, weak rainbands of a tropical cyclone's stationary band complex, embedded in the stratiform...
• Secondary circulationA circulation induced by and superimposed on a primary circulation, usually weaker than the flow that drives...
• Secondary cold frontA cold front that forms behind a primary cold front, bringing a renewed surge of colder air and often...
• Secondary cycloneA low-pressure system that forms or develops along the trailing cold front or occluded front of a larger...
• Secondary depressionA low-pressure area that forms on the periphery of a larger, more established low-pressure system, often...
• Secondary emissionThe release of electrons from a solid surface when it is struck by energetic primary particles such as...
• Secondary frontA frontal boundary that develops within a larger air mass or behind a primary frontal system, marking a...
• Secondary hydrometric stationA river or lake gauging station operated for only a limited number of years to add records beyond those of...
• Secondary ice crystalAn ice particle produced in a cloud by the fragmentation or splintering of existing ice, rather than by...
• Secondary instrumentAn instrument whose calibration is determined by comparing its measurements against those of a primary or...
• Secondary pollutantPollutants generated by chemical reactions occurring within the atmosphere. Compare primary pollutant.
• Secondary pollutants, see Secondary pollutant
• Secondary rainbowA fainter, outer rainbow that appears above the primary rainbow, formed by two internal reflections of...
• Second-day feetIn hydrologic terms, the volume of water represented by a flow of one cubic foot per second for 24 hours...
• Second-foot dayA unit of water volume, representing the amount of water that flows at a rate of one cubic foot per second...
• Second-order climatological stationA weather observation site that records data at least once daily for a more limited set of atmospheric...
• Second-order closureA modeling technique used in atmospheric science to represent turbulent fluxes by deriving prognostic...
• Second-order reactionA chemical reaction in which the rate is proportional to the product of the concentrations of two reactants...
• Second-order stationA meteorological station where observations are taken by a trained but unpaid volunteer observer at least...
• Second-trip echoA radar echo that originates from a target located beyond the maximum unambiguous range of the radar, but is...
• Second-year iceSea ice that has survived one summer melt season and is typically thicker and stronger than first-year ice...
• Sector boundaryIn solar-terrestrial terms, in the solar wind, the area of demarcation between sectors, which are large-scale...
• Sector scanA mode of radar operation where the antenna sweeps back and forth over a limited angular range rather than...
• Sector visibilityThe visibility in a specific direction that represents at least a 45º arc of a horizontal circle.
• Sectorized hybrid scanA single reflectivity scan composed of data from the lowest four elevation scans. Close to the radar, higher...
• Sectorized imageA satellite or radar image that displays data for a specific geographic region or angular segment, rather...
• Secular variationA slow, non-periodic change in a climatic or geophysical quantity that persists over decades to centuries, as...
• SecuriteA headline within National Weather Service high seas forecasts transmitted via the GMDSS to indicate that no...
• SedimentSolid material, such as rock fragments, mineral grains, or organic matter, that is transported and deposited...
• Sediment concentrationThe amount of sediment carried by a fluid, expressed as the dry mass of particles per unit volume of the...
• Sediment discharge ratingA relationship, often expressed as a curve or equation, that describes the rate at which sediment is...
• Sediment gradingThe classification of sediment particles based on their size distribution, ranging from fine clays to coarse...
• Sediment samplerA device designed to collect samples of particulate matter from a fluid medium, such as air, water, or ice...
• Sediment storage capacityIn hydrologic terms, the volume of a reservoir planned for the deposition of sediment.
• Sediment yieldThe total mass or volume of sediment transported out of a drainage basin over a specified period. This...
• SedimentationThe process by which solid particles settle out of a fluid, such as air or water, and accumulate on a...
• Sedimentation diameterThe diameter of a sphere of a specified density that has the same settling velocity in a given fluid as the...
• Sediment-carrying capacityThe maximum amount of sediment that a fluid, such as air or water, can transport under given flow conditions...
• SedimentologyThe scientific study of sediments and sedimentary rocks, including their formation, transport, deposition...
• Seeder-feederA mechanism of precipitation enhancement in which particles falling from a higher seeder cloud pass through a...
• Seeding agentA substance introduced into clouds to modify their microphysical processes, typically to enhance...
• Seeding devicesEquipment used to disperse cloud seeding agents into the atmosphere. These devices include aircraft-mounted...
• Seeding rateThe quantity of cloud seeding agent released into a cloud per unit of time or per unit of cloud volume. This...
• SeeingA measure of the atmospheric stability and clarity that affects the quality of astronomical observations. It...
• SeepageIn hydrologic terms, the interstitial movement of water that may take place through a dam, its foundation, or...
• Seepage faceA saturated zone on a slope, such as a riverbank or hillside, where groundwater emerges and flows out onto...
• Seepage springA type of spring where groundwater slowly emerges from the ground over a diffuse area, rather than from a...
• Seepage velocityThe actual average velocity of groundwater flow through the pores and interstices of a porous medium. This...
• SeicheA standing wave oscillation in an enclosed or semi-enclosed body of water, such as a lake, bay, or even an...
• SeistanA region in eastern Iran and southwestern Afghanistan known for its strong, persistent summer winds. These...
• SELA watch cancellation statement issued to terminate a watch before its original expiration time.
• Selection rulesPrinciples in quantum mechanics that determine whether a transition between two energy states of an atom or...
• Selective absorptionThe process by which a substance absorbs electromagnetic radiation more strongly at certain wavelengths than...
• Selective Chopper RadiometerAn infrared radiometer flown on the Nimbus 4 and Nimbus 5 satellites that sounded stratospheric temperature...
• Selective scatteringThe process where electromagnetic radiation is scattered differently depending on its wavelength. In the...
• Self-collectionA process in cloud physics where cloud droplets or ice crystals collide and coalesce with others of similar...
• Self-healing of atmosphereThe natural processes by which the Earth's atmosphere removes pollutants and recovers from disturbances. This...
• SELSSevere Local Storm
• SelsynA type of electromechanical device used for transmitting angular position data remotely. In meteorology...
• SelvasThe dense tropical rainforests characteristic of the Amazon River basin in South America. This ecosystem is...
• SELYSoutheasterly
• Semantic networkA knowledge representation framework that models concepts and their relationships as a graph, where nodes...
• Semiannual oscillationA periodic variation in atmospheric parameters, such as wind or pressure, that exhibits a primary cycle of...
• Semiarid climateA climate type characterized by low annual precipitation that is insufficient to support dense forests but...
• Semiarid zoneA geographical region characterized by a semiarid climate, receiving limited precipitation that supports...
• Semidiurnal tideA tidal pattern characterized by two high tides and two low tides of approximately equal height within each...
• Semigeostrophic equationsA set of simplified equations of motion used in atmospheric dynamics that retain some ageostrophic effects...
• Semigeostrophic motionAtmospheric flow that is approximately in geostrophic balance but includes some ageostrophic components...
• Semigeostrophic theoryA theoretical framework in atmospheric dynamics that describes large-scale and mesoscale atmospheric flows...
• Semi-implicit methodA numerical integration technique used in atmospheric models to solve prognostic equations, where some terms...
• semi-Lagrangian methodA numerical advection scheme used in atmospheric models that traces parcels of air backward in time from grid...
• Semipermanent anticycloneA large, persistent high-pressure system that maintains its general location and influence over a particular...
• Semipermanent depressionA large, persistent low-pressure system that tends to remain in a particular geographical area for extended...
• Sensible heatThermal energy that can be felt and measured by a thermometer, causing a change in the temperature of a...
• Sensible heat flowThe transfer of thermal energy between the Earth's surface and the atmosphere through conduction and...
• Sensible heat fluxThe flux of heat from the earth's surface to the atmosphere that is not associated with phase changes of...
• Sensible temperatureA measure of how warm or cold the human body perceives the ambient environment to be, taking into account not...
• Sensing elementThe part of an instrument that directly interacts with the physical quantity being measured and produces a...
• SensitivityThe degree to which an instrument or system responds to a change in the input quantity it is designed to...
• Sensitivity time controlA radar receiver feature that lowers the gain for echoes arriving soon after each pulse and lets it rise with...
• Sentinel-1 (S1)A European Space Agency satellite remote sensing mission which images with a 5cm wavelength Synthetic...
• Sentinel-2 (S2)A European Space Agency satellite remote sensing mission which images with a multi-spectral scanner.
• Separation eddyAn eddy that forms near the ground on the windward or leeward side of a bluff object or steeply rising...
• Separation of variablesA mathematical technique used to solve certain types of partial differential equations by assuming that the...
• SequenceA series of atmospheric events or data points arranged in chronological order. This arrangement allows for...
• SeracA large, unstable block or tower of glacial ice, often found in icefalls or at the edge of ice cliffs where...
• SereinRain that falls from an otherwise clear sky, without visible clouds overhead. This phenomenon occurs when...
• Serial communicationsA method of data transmission where bits of information are sent sequentially over a single communication...
• Serial correlationThe statistical relationship between observations of a time series and previous observations in that same...
• Serial derechoType of derecho that consists of an extensive squall line which is oriented such that the angle between the...
• Serial stationAn oceanographic station at which water temperature and samples are taken at a series of depths from the...
• SERNSoutheastern
• Service hydrologistThe designated expert of the hydrology program at a WFO.
• Servo loopA closed-loop control system that uses feedback to maintain a desired output, typically a position, speed, or...
• SetThe daily disappearance of a celestial body, such as the sun or moon, below the horizon as a result of...
• Set-upThe process whereby strong winds blowing down the length of a lake cause water to "pile up" at the downwind...
• Severe icingThe rate of ice accumulation on an aircraft is such that de-icing/anti-icing equipment fails to reduce or...
• Severe local stormA convective storm that usually covers a relatively small geographic area, or moves in a narrow path, and is...
• Severe local storm watchAn alert issued by the National Weather Service for the contiguous U.S. and its adjacent waters of the...
• Severe stormA localized atmospheric disturbance characterized by intense weather phenomena that pose a threat to life and...
• Severe thunderstormA thunderstorm that produces a tornado, winds of at least 58 mph (50knots), and/or hail at least 1" in...
• Severe thunderstorm warningThis is issued when either a severe thunderstorm is indicated by the WSR-88D radar or a spotter reports a...
• Severe thunderstorm watchThis is issued by the National Weather Service when conditions are favorable for the development of severe...
• Severe weatherAny hazardous meteorological phenomenon with the intensity to pose a threat to life, property, or public...
• Severe weather analysisThis WSR-88D radar product provides 3 base products (reflectivity (SWR), radial velocity (SWV), and spectrum...
• Severe weather potential statementThis statement is designed to alert the public and state/local agencies to the potential for severe weather...
• Severe weather probabilityThis WSR-88D radar product algorithm displays numerical values proportional to the probability that a storm...
• Severe weather statementA National Weather Service product which provides follow up information on severe weather conditions (severe...
• Severe weather threat indexA composite stability index, known as SWEAT, computed from an upper-air sounding by combining the 850 hPa dew...
• Severe-storm observationA report of a severe weather event, such as a tornado, large hail, or damaging winds, made by a trained...
• SEWDSoutheastward
• SFCSurface
• SfericIn solar-terrestrial terms, a transient electric or magnetic field generated by any feature of lightning...
• SfericsElectromagnetic impulses generated by lightning discharges, which propagate through the atmosphere as radio...
• Sferics fixA geographical location determined by triangulating the radio signals emitted by lightning discharges...
• Sferics observationThe detection and analysis of radio frequency electromagnetic signals, known as atmospherics, that are...
• Sferics receiverAn electronic device designed to detect and process the electromagnetic impulses generated by lightning. This...
• Sferics sourceA lightning discharge that emits electromagnetic radiation, detectable as sferics. These sources are...
• SGSnow grains
• SGFNTSignificant
• ShadowA region of reduced or absent direct solar radiation caused by an opaque object obstructing the path of...
• Shadow band pyranometerA pyranometer used with a band or ring that shades its sensor from the direct solar beam, either continuously...
• Shadow bandsFaint, wavy, alternating light and dark bands seen moving across plain light surfaces in the minutes just...
• Shadow zoneA region where waves from a source are not detected because refraction bends the rays away from it. For sound...
• Shale iceA form of ice that develops in thin, brittle layers, resembling flakes or shards of shale rock. It forms on...
• Shallow convection parameterizationA set of mathematical equations and assumptions used in numerical weather and climate models to represent the...
• Shallow fogA fog layer lying close to the ground, defined in aviation reports as no deeper than about 2 meters (6 feet)...
• Shallow lowA low-pressure system with a cyclonic circulation that is confined to the lower part of the troposphere. The...
• Shallow water approximationA set of simplifying assumptions used in fluid dynamics to model wave propagation in a fluid layer where the...
• Shallow water waveA type of wave that propagates in a fluid layer where the water depth is much less than the wavelength. The...
• ShamalA persistent, northwesterly wind that blows over Iraq and the Persian Gulf region, particularly during the...
• Sharp-edged gustAn idealized gust in which the wind component jumps abruptly, as a step, to its full value and then stays...
• SHARSSubtle Heavy Rainfall Signature
• ShearThe variation of wind velocity over a given distance, either horizontally or vertically. This differential...
• Shear flowA fluid motion where adjacent layers of the fluid move at different velocities, resulting in a velocity...
• Shear layerA region within the atmosphere where there is a substantial gradient in wind velocity, either in speed or...
• Shear lineA narrow zone across which the horizontal wind component parallel to the line changes abruptly, usually with...
• Shear productionThe process by which kinetic energy from the mean flow is converted into turbulent kinetic energy due to the...
• Shear ridgeA pressure ridge in sea ice that forms primarily due to shear motion, where two ice floes or fields slide...
• Shear vectorA vector representing the change in wind velocity over a specified distance or height. It quantifies both the...
• Shear waveA type of wave in which the particles of the medium oscillate perpendicular to the direction of wave...
• Shear-gravity waveAn atmospheric wave that arises from the interaction between vertical wind shear and buoyancy forces, often...
• Shearing instabilityA fluid dynamic instability that arises in a flow with a strong velocity gradient, where the kinetic energy...
• Shearing stressA force per unit area acting tangentially to a surface, caused by the differential motion of adjacent fluid...
• Sheet erosionThe uniform removal of a thin layer of topsoil from a large area by the action of rainfall and surface...
• Sheet flowIn hydrologic terms, flow that occurs overland in places where there are no defined channels, the flood water...
• Sheet frostA thin, uniform layer of ice crystals that forms on surfaces when water vapor in the air directly sublimates...
• Sheet iceA broad, relatively thin expanse of ice that forms on the surface of water bodies, such as lakes, rivers, or...
• Sheet lightningA diffuse illumination of the sky from a distant lightning discharge where the individual lightning channel...
• Shelf cloudA low-hanging, wedge-shaped or arc-shaped accessory cloud attached to the base of a cumulonimbus or...
• Shelf wavesOceanic waves that propagate along continental shelves, characterized by their dependence on the varying...
• Shell iceA thin, hollow layer of ice that forms on the surface of water, often enclosing a pocket of air or water...
• ShelterbeltA barrier of trees or shrubs planted to protect an area from wind, snow, or other adverse weather conditions...
• Sheltering coefficientThe dimensionless coefficient in Jeffreys' theory of wave generation by wind that scales the air pressure...
• SherkiA southeasterly wind of the Persian Gulf region, one of several spellings of the Arabic name sharqi, meaning...
• SHFSuper high frequency, referring to the portion of the electromagnetic spectrum with frequencies between 3 and...
• SHFTShift
• ShieldA protective barrier or structure that deflects or absorbs atmospheric phenomena, such as wind...
• ShineThe direct emission of light from the sun, often referring to periods of clear skies when solar radiation...
• Ship motionThe movement of a vessel at sea in response to forces from waves, wind, and currents. This motion is...
• Ship reportA meteorological observation made by personnel on board a ship and transmitted to shore-based weather...
• Ship routingThe process of selecting an optimal path for a vessel to travel between two points, based on weather...
• Ship synoptic codeA standardized format for transmitting meteorological observations from ships at sea to weather forecasting...
• SHLWShallow
• ShoalA submerged ridge, bank, or bar composed of sand or other unconsolidated material that rises from the seabed...
• ShoalingThe process by which ocean waves encounter decreasing water depth as they approach a coastline or shallow...
• Shock waveA propagating disturbance front that carries energy and travels through a medium faster than the local speed...
• Shore iceIce that is attached to the coastline or to the seabed in shallow waters, remaining fast and unmoved by...
• Shore leadA navigable channel of open water that forms between the landfast ice and the moving pack ice in polar...
• Short term forecastA product used to convey information regarding weather or hydrologic events in the next few hours.
• Short waveA disturbance or trough in the mid-to-upper levels of the troposphere that moves along with the main westerly...
• Short Wave FadeIn solar-terrestrial terms, a particular ionospheric solar flare effect under the broad category of sudden...
• Short-crested waveAn ocean wave characterized by a crest length that is comparable to or shorter than its wavelength, appearing...
• Short-fuse warningA warning issued by the NWS for a local weather hazard of relatively short duration. Short-fuse warnings...
• Short-range forecastA weather prediction that covers a relatively brief period, typically from a few hours up to 72 hours in...
• Short-term hydrologic forecastA prediction of streamflow, water levels, or soil moisture conditions for a period extending from a few hours...
• Short-Term Prediction Research and TransitionA NASA- and NOAA-funded activity to transition experimental/quasi-operational satellite observations and...
• Short-Term Prediction Research and Transition Center - Land Information SystemProvides high-resolution (~3 km) gridded soil moisture products in real-time to support regional and local...
• ShortwaveAlso known as Shortwave Trough; a disturbance in the mid or upper part of the atmosphere which induces upward...
• Shortwave radiationElectromagnetic radiation with wavelengths typically between 0.1 and 4.0 micrometers, primarily originating...
• Shortwave troughAlso called Shortwave; A disturbance in the mid or upper part of the atmosphere which induces upward motion...
• Showalter index(Abbrev. SWI) - a stability index used to determine thunderstorm potential. The SWI is calculated by lifting...
• ShowerPrecipitation from a convective cloud, characterized by its sudden onset, rapid changes in intensity, and...
• SHRARain showers
• SHRASshowers
• SHRTShort
• SHRTWVShortwave - a disturbance in the mid or upper part of the atmosphere which induces upward motion ahead of it...
• SHSNSnow showers
• ShugaAn accumulation of spongy, white ice lumps, a few centimeters across, that form in water with a high...
• ShurgeeA dry, dusty wind from the south or southeast over the Persian Gulf and Iraq, a spelling variant of the...
• ShurkiyaA south to southeasterly wind of the Persian Gulf area, a transliteration variant of the sharqi, whose name...
• SHWRShower
• SIThe International System of Units, a globally recognized system of measurement based on seven base units...
• Siberian highA massive, semi-permanent anticyclone that forms over Siberia during the winter months, characterized by...
• SidebandA band of frequencies higher or lower than the carrier frequency in a modulated signal, containing the...
• SidelobeA secondary energy maximum located outside the main radar beam. Typically, it contains a small percentage of...
• Sidelooking radarA type of radar system that emits microwave pulses perpendicular to the direction of motion of the platform...
• Sidereal yearThe time it takes for the Earth to complete one full orbit around the Sun with respect to the fixed stars...
• Side-scanning sonarAn acoustic imaging system used to create detailed images of the seafloor and submerged objects. It emits...
• SiffantoA warm wind from the south or southwest that blows over the Adriatic Sea, arriving from the direction of the...
• Sigma vertical coordinateA normalized pressure coordinate system used in atmospheric models where the vertical coordinate is defined...
• Sigma-thetaThe potential density anomaly of seawater: the density a water sample would have if brought adiabatically to...
• Sigma-zeroThe normalized radar cross-section per unit area of a distributed target, often expressed in decibels. In...
• SIGMETSignificant Meteorological Advisory
• SIGMET informationAeronautical advisories on en-route weather phenomena that could affect the safety of aircraft operations...
• SignalThe part of a time series of data that represents the true, systematic variation of a physical quantity, as...
• Signal strengthThe magnitude of a received electromagnetic signal from a remote sensing instrument, such as a weather radar...
• Signal velocityThe speed at which a signal propagates through a medium, which can differ from the phase velocity or group...
• Signal-to-noise ratioA measure comparing the power of a desired signal to the power of background noise, abbreviated as SNR. It...
• SignatureA characteristic pattern or set of features in meteorological data that indicates a specific weather...
• Signature analysis techniquesMethods used to identify and classify atmospheric phenomena or constituents based on their unique...
• Significance testA statistical method used to determine if an observed difference or relationship between datasets is likely...
• Significant levelThe probability threshold used in a statistical significance test to decide whether to reject the null...
• Significant waveA conceptual wave representing the average height of the highest one-third of waves in a given wave train or...
• Significant wave heightThe average height of the highest one-third of waves in a wave spectrum or observed sea state. This metric...
• Significant weather chartA meteorological chart that depicts areas of significant weather phenomena expected to affect aviation within...
• Significant weather outlookA narrative statement produced by the National Weather Service, frequently issued on a routine basis, to...
• SIGWXSignificant Weather
• SikussakA type of very old, thick, and highly consolidated sea ice found in the Arctic, often persisting for many...
• Sill depthThe shallowest depth of a submarine ridge or barrier that separates two basins or a basin from the open...
• SiltFine-grained particulate matter suspended in the atmosphere or deposited on surfaces, originating from...
• Silt-discharge ratingA relationship that describes the concentration or load of suspended silt in a river or stream as a function...
• Silver frostA smooth, clear coating of ice on exposed surfaces, produced when supercooled rain or drizzle freezes on...
• Silver iodideA chemical compound used as a cloud seeding agent to induce precipitation or modify existing clouds. Its...
• Silver-disk pyrheliometerA pyrheliometer designed by Abbot at the Smithsonian Institution, in which a tube limits sunlight to a...
• SimilarityA concept in fluid dynamics and atmospheric modeling where two different flow systems exhibit similar...
• Similarity relationshipA mathematical expression that describes the scaling behavior between different physical quantities in fluid...
• Similarity theoryA theoretical framework used to describe the mean profiles of atmospheric variables within the surface layer...
• SimoomA strong, hot, and dry wind that blows across the deserts of the Arabian Peninsula, North Africa, and the...
• Simple harmonic waveA wave whose displacement at any point varies sinusoidally with time, and whose spatial variation is also...
• Simple waveA nonlinear wave solution of a hyperbolic system, such as gas dynamics or shallow-water flow, in which a...
• Single cell thunderstormThis type of thunderstorm develops in weak vertical wind shear environments. On a hodograph, this would...
• Single observer forecastingA technique of forecasting from weather observations made at a single place, usually aboard a ship or at a...
• Single scatteringThe process where an electromagnetic wave or particle interacts with only one scattering center in a medium...
• Single-heading navigationAn aircraft navigation technique where a pilot flies a constant magnetic heading for a segment of a flight...
• Single-scatter albedoThe ratio of the radiation scattered by a particle to the total radiation extinguished by that particle...
• Single-station analysisThe meteorological analysis of atmospheric conditions based primarily on observations from a single weather...
• Single-station forecastingA method of weather prediction based on observations from a single location without reference to a broader...
• Single-theodolite observationA method for determining wind speed and direction in the upper atmosphere by tracking the movement of a pilot...
• Singular pointA point in a mathematical system where a function or its derivatives are undefined, or where the behavior of...
• Singular value decompositionA matrix factorization technique that decomposes a matrix into three other matrices, revealing its underlying...
• Singular vectorsSpecific perturbation patterns that exhibit the largest possible growth over a finite time interval in a...
• SingularityA point or region in a mathematical model or physical system where certain properties become infinite...
• SinkA process or region that removes a substance, such as a gas or aerosol, from the atmosphere. Sinks can be...
• Sink processes for trace gasesMechanisms that remove trace gases from the atmosphere, thereby controlling their concentration and lifetime...
• SinkholeA depression or hole in the ground surface caused by the collapse of the surface layer into an underlying...
• SinkingThe downward movement of air in the atmosphere, also known as subsidence. This motion typically leads to...
• SinteringThe gradual bonding of snow or ice grains where they touch, as water molecules move by vapor transport and...
• Sinusoidal patternA recurring waveform that oscillates smoothly and periodically, resembling a sine or cosine function. In...
• Siphon barographA type of barograph that uses a siphon barometer to record atmospheric pressure changes over time. The...
• Siphon barometerA type of mercury barometer consisting of a U-shaped tube with one arm open to the atmosphere and the other...
• SiroccoA hot, dry, and dusty wind originating from the Sahara Desert that blows across North Africa and into...
• Site characterizationThe process of investigating and describing the physical, chemical, and biological properties of a specific...
• Site of stationThe specific geographical location and immediate surroundings of a meteorological observing station. The...
• SITOR(SImplex Teletype Over Radio) - a means of transmitting text broadcasts over radio. The U.S. Coast Guard...
• Six's thermometerA U-shaped glass tube containing mercury and alcohol, designed to show the highest and lowest temperatures...
• Size parameterA dimensionless quantity used in scattering theory, defined as 2πr/λ, where 'r' is the radius of a scattering...
• SkavlerA sharp, irregular ridge cut into a snow surface by wind scouring and drifting, the Norwegian name for what...
• Skew t-logp diagramA thermodynamic diagram used in meteorology to plot atmospheric soundings, displaying temperature and dew...
• SkewnessA statistical measure of a distribution's asymmetry around its mean, indicating the direction and relative...
• SkillA measure of the accuracy of a forecast relative to a reference forecast, such as a climatological average or...
• Skin dragThe frictional force exerted on a surface by a fluid, such as air, moving across it. This drag is caused by...
• Skin frictionThe tangential drag force per unit area exerted on a surface by a fluid, produced by viscous shear within the...
• Skin-friction coefficientA dimensionless quantity that relates the skin friction drag per unit area to the dynamic pressure of the...
• Skip effectA phenomenon in radio wave propagation where signals are received at a distance from the transmitter but not...
• SkironThe classical Greek name for the northwest wind, one of the eight wind figures carved on the Tower of the...
• SkyThe visible expanse above the Earth's surface, where atmospheric phenomena such as clouds, precipitation, and...
• Sky conditionUsed in a forecast to describes the predominant/average sky condition based upon octants (eighths) of the sky...
• Sky coverThe fraction of the sky obscured by clouds or obscuring phenomena such as fog or haze, as observed from a...
• Sky luminanceThe photometric measure of the luminous intensity emitted or reflected by the sky in a given direction, per...
• Sky mapA graphical representation of the celestial sphere, showing the positions of stars, constellations, and other...
• Sky slightly cloudedA sky cover condition where clouds are present but their total coverage is minimal. In standard...
• Sky waveA radio wave that travels upward into the atmosphere and is reflected or refracted back to Earth by the...
• Sky-ground luminance ratioThe ratio of the luminance of the sky to the luminance of the ground, a measure used in daylighting design...
• Skyhook balloonA large, uncrewed balloon designed to carry scientific instruments to high altitudes in the stratosphere for...
• SKYWARNA nationwide network of volunteer weather spotters who report to and are trained by the National Weather...
• SLSea Level
• Slab approximationA simplification used in atmospheric modeling where a layer of the atmosphere is treated as a horizontally...
• Slab layerA cohesive layer of snow that forms on top of a weaker, underlying snowpack, often due to wind deposition or...
• Slab modelA simplified climate or atmospheric model that represents a component of the Earth system, such as the ocean...
• Slablike motionA conceptual model of fluid motion where a layer or parcel of air moves horizontally as a single, coherent...
• Slack waterThe short interval at the turn of a tidal current, when the water is momentarily at rest between the flood...
• SlakeTo disintegrate or crumble when exposed to water, a process often observed in certain types of soil or rock...
• Slant rangeThe direct distance between an observer or sensor and a target, measured along a straight line in...
• Slant visibilityThe maximum distance at which an observer can see and identify objects along a line of sight that is inclined...
• Slantwise convectionConvection in which air parcels move along sloping surfaces of constant absolute momentum rather than...
• Slantwise convective available potential energyThe energy available to air parcels that move along sloping surfaces of constant absolute momentum in a...
• SLDSolid
• SleetPrecipitation consisting of transparent or translucent pellets of ice, which are spherical or irregular, and...
• Sleet warningIssued when accumulation of sleet in excess of 1/2" is expected; this is a relatively rare scenario. Usually...
• SLGTSlight
• Slice methodA method, introduced by Bjerknes in 1938, of assessing the stability of the atmosphere to convection that...
• Slight chanceIn probability of precipitation statements, usually equivalent to a 20 percent chance.
• Slight risk(of severe thunderstorms)- Severe thunderstorms are expected to affect between 2 and 5 percent of the area. A...
• Sling psychrometerAn instrument used to measure atmospheric humidity, consisting of two thermometers mounted together on a...
• Sling thermometerA type of psychrometer used to measure atmospheric humidity, consisting of two thermometers, one dry-bulb and...
• SLOSlow
• Slope area methodA technique used in hydrology to estimate peak discharge in rivers and streams, particularly after floods, by...
• Slope flowA localized wind system driven by differential heating or cooling of a sloping terrain, causing air to move...
• Slope of a frontThe inclination of a frontal surface, which is the boundary between two air masses of different temperatures...
• Slope of an isobaric surfaceThe inclination of a surface of constant atmospheric pressure relative to a horizontal plane. This slope is...
• Slope WaterA water mass in the Northwest Atlantic Ocean located between the continental shelf and the Gulf Stream...
• Slope windsLocal winds that develop along hillsides and mountain slopes due to differential heating and cooling of the...
• Slope windstormA localized, strong wind event that occurs on the lee side of mountain ranges, often characterized by high...
• SLOSH(Sea, Lake and Overland Surges from Hurricanes) - A computer model run by the National Hurricane Center (NHC)...
• Slow manifoldA concept in dynamical systems theory describing a lower-dimensional space within the system's full phase...
• Slow tailThe long, slowly varying part of a radio atmospheric (sferic) waveform that follows its initial sharp pulse...
• SLPSea Level Pressure
• SLT1. Slight (as in "slight chance")
• SludgeA viscous, soupy floating mass of ice crystals and water that forms in the early stage of freezing of sea...
• SluffA small, loose-snow avalanche that involves only surface layers of snow and does not contain a cohesive slab...
• Slug testA hydrogeological test performed in a well to determine the hydraulic conductivity of an aquifer. It involves...
• SlushA semi-liquid mixture of snow and water, typically found on the ground when temperatures are near or slightly...
• Slush icingA form of aircraft icing met when flying through a mixture of water droplets and melting snow, found near the...
• SLYSoutherly
• SM1) Statute Miles
• SMAThe Soil Moisture Accounting Model.
• Small circleA circle on the surface of a sphere whose plane does not pass through the center of the sphere. In contrast...
• Small craftThere is no precise definition for small craft. Any vessel that may be adversely affected by Small Craft...
• Small craft advisory(SCA) - An advisory issued by coastal and Great Lakes Weather Forecast Offices (WFO) for areas included in...
• Small craft should exercise cautionPrecautionary statement issued to alert mariners with small, weather sensitive boats.
• Small eddy closureA modeling approach used in fluid dynamics, including atmospheric and oceanic sciences, to represent the...
• Small eddy theoryA turbulence closure theory, also called K-theory, that assumes the eddies carrying a flux are small compared...
• Small hailPrecipitation of translucent ice particles, spherical or conical and up to about 5 millimeters across, each...
• Small ionAn atmospheric ion with high mobility, consisting of a single charged molecule or a small cluster of...
• Small perturbationA minor deviation or disturbance from a basic, steady, or mean state in a physical system, such as the...
• Small stream floodingIn hydrologic terms, flooding of small creeks, streams, or runs.
• Small-craft warningA weather advisory issued by meteorological services to alert operators of small vessels to hazardous...
• Small-ion combinationThe process by which small atmospheric ions, which are highly mobile charged molecules or molecular clusters...
• SmazeAn atmospheric condition characterized by a mixture of smoke and haze, resulting in reduced visibility. This...
• SmogA visible air pollution haze that reduces visibility, named from smoke and fog. Classical or London-type smog...
• Smog chambersControlled environmental enclosures used to study atmospheric chemical reactions under simulated conditions...
• SmokeA visible suspension of solid and liquid particles in a gas, produced by incomplete combustion of organic...
• Smoke dispersalDescribes the ability of the atmosphere to ventilate smoke. Depends on the stability and winds in the lower...
• Smoke horizonA distinct layer of reduced visibility caused by the presence of smoke particles in the atmosphere, often...
• Smoke managementThe use of meteorology, fuel moisture, fuel loading, fire suppression and burn techniques to keep smoke...
• Smoke pallA widespread and dense layer of smoke that covers a large geographical area, significantly reducing sunlight...
• Smoke plumesColumns or trails of smoke rising and dispersing into the atmosphere from a source of combustion. These...
• Smokes, see Smoke
• Smoothed sunspot numberAn average of 13 monthly RI numbers, centered on the month of concern.
• SmoothingA statistical or numerical procedure applied to data to remove or reduce short-term fluctuations, noise, or...
• SmudgingA frost protection practice of burning oil or other materials in an orchard or field on clear, calm nights to...
• SMW(Special Marine Warning) - A warning product issued for potentially hazardous weather conditions usually of...
• SNsnow
• Snel's lawA formula describing the change in direction of a wave as it passes from one medium to another. The law...
• SNOTELAn automated network of data collection sites that measures snowpack and related climatic data in the western...

1,280 of 10,756 terms in Meteorology and atmospheric science terminology (MLC-0110). Request the full dataset.