SublimationThe transition of a substance from the solid phase directly to the vapor phase, or vice versa, without passing through an intermediate liquid phase.
SubsidenceSinking or settlement of the land surface, due to any of several processes. As commonly used, the term relates to the vertical downward movement of…
Sulfate AerosolsParticulate matter that consists of compounds of sulfur formed by the interaction of sulfur dioxide and sulfur trioxide with other compounds in the…
Sulfur cycleCyclic movement of sulfur in different chemical forms from the environment, to organisms, and then back to the environment.
Sulfur dioxide (SO<sub>2</sub>)A compound composed of one sulfur and two oxygen molecules. Sulfur dioxide emitted into the atmosphere through natural and anthropogenic processes is…
Sulfur Hexafluoride (SF6)A colorless gas soluble in alcohol and ether, slightly soluble in water. A very powerful greenhouse gas used primarily in electrical transmission and…
Sulfur Hexafluoride (SF<sub>6</sub>)A colorless gas soluble in alcohol and ether, slightly soluble in water. A very powerful greenhouse gas used primarily in electrical transmission and…
Sun PillarA bright column above or below the sun produced by the reflection of sunlight from ice crystals.
sundogA colored luminous spot produced by refraction of light through ice crystals that appears on either side of the sun. Also called parhelion.
SupercoolTo cool a liquid below its freezing point without solidification or crystallization.
supersaturated airA condition that occurs in the atmosphere when the relative humidity is greater that 100 percent.
surface albedoThe fraction of incoming solar radiation at a surface (i.e., land, cloud top) that is effectively reflected by that surface.
surface conditionState of the surface, including vegetation, land use, surface type, roughness, and such; often provided in model output.
Surface Energy BudgetThe energy or heat budget at the earth's surface, considered in terms of the fluxes through a plane at the earth-atmosphere interface.
Surface miningRemoval of soil, sub-soil, and other strata and then extracting a mineral deposit found fairly close to the earth's surface. See strip mining.
surface moisture fluxThe vertical flux of surface moisture due to atmospheric turbulent transport.
Surface observationSurface observation A meteorological observation made on the Earth's surface in contrast with an upper-air observation).
surface skin temperatureThe radiative surface skin temperature, from an infrared thermometer measuring the narrowband radiating temperature of the ground surface in its field of…
surface stressThe vertical flux of momentum near the surface as the the ambient flow interacts with the land/water surface.
Surface Weather ChartAn analyzed synoptic chart of surface weather observations. A surface chart shows the distribution of sea-level pressure (therefore, the position of…
Surface windSurface wind Wind blowing near the Earth's surface. It is measured, by convention, at a height of 10 m above ground in an area where the distance between…
Sverdrupa unit of measure of volume transport equal to 106 m3/s, named in honor of the oceanographer Harald Sverdrup.
Synoptic analysisSynoptic analysis The study of the synoptic observation data plotted on synoptic charts aimed at analysis of the atmospheric disturbances (for example…
Synoptic chartSynoptic chart A weather chart reflecting the state of the atmosphere over a large area at a given moment.
Synoptic CodeRules and procedures established by the World Meteorological Organization(WMO) for encoding weather observations.
Synoptic hourSynoptic hour Hour (UTC) determined by international agreement at which meteorological observations are made simultaneously throughout the world.
Synoptic meteorologySynoptic meteorology The study and analysis of synoptic weather information (synoptic charts, synoptic weather observations).
Synoptic ScaleThe spatial scale of the migratory high and low pressure systems of the lower troposphere, with wavelengths of 1000 to 2500 km.
Synoptic weather observationSynoptic weather observation A surface weather observation, made at periodic times (usually at 3-hourly and 6-hourly intervals specified by the World…
Synthetic fertilizerCommercially prepared mixtures of plant nutrients such as nitrates, phosphates, and potassium applied to the soil to restore fertility and increase crop…
Synthetic natural gas (SNG)A manufactured product chemically similar in most respects to natural gas, resulting from the conversion or reforming of petroleum hydrocarbons.
TailingsSecond grade or waste material separated from pay material during screening or processing.
Tar sandSwamp-like deposit of a mixture of fine clay, sand, water, and variable amounts of tar-like heavy oil known as bitumen.
TeleconnectionLinkage between changes in atmospheric circulation occurring in widely separated parts of the globe.
Temperature(Abbrev. TEMP)- The temperature is a measure of the internal energy that a substance contains. This is the most measured quantity in the atmosphere.
Temperature Inversion(surface-based or elevated) : a layer of the atmosphere in which air temperature increases with height.
TephraA general term for fragments of volcanic rock and lava, regardless of size, that are blasted into the air by explosions or carried upward by hot gases in…
terminal velocityThe constant speed obtained by a falling object when the upward drag on the object balances the downward force of gravity.
Terrestrial radiationThe total infrared radiation emitted by the Earth and its atmosphere in the temperature range of approximately 200 to 300 Kelvin.
terrigenousderived from land areas. For example, wind-blown dust from desert areas can settle into oceans and form terrigenous sediment on the sea floor.
ThermalA relatively small-scale, rising air current produced when the Earth's surface is heated.
Thermally Driven CirculationA diurnally reversing closed cellular wind current resulting from horizontal temperature contrasts caused by different rates of heating or cooling over…
ThermistorA resistor whose resistance changes with temperature. Because of the known dependence of resistance on temperature, the resistor can be used as a…
ThermographAn instrument that measures and records air temperature.
Thermohaline CirculationLarge-scale density-driven circulation in the ocean, caused by differences in temperature and salinity.
thermohaline circulation (THC)density-driven circulation system in the world's oceans. In the Atlantic, warm water flows northward in the surface ocean, loses heat to the overlying…
ThermometerAn instrument for measuring air temperature.
Thresholdthe point a system must cross to enter a new state or condition.
ThunderThe sound caused by rapidly expanding gases in a lightning discharge.
ThunderstormA local storm produced by a cumulonimbus cloud and accompanied by lightning and thunder.
TornadoA violently rotating column of air, usually pendant to a cumulonimbus, with circulation reaching the ground.
total carbonThe total concentration of carbon in all its organic and non-organic forms.
total cloud waterThe total concentration (mass/vol) of ice and liquid water particles in a cloud.
Trace GasAny one of the less common gases found in the Earth's atmosphere. Nitrogen, oxygen, and argon make up more than 99 percent of the Earth's atmosphere.
Trade WindsPersistent tropical winds that blow from the subtropical high pressure centers towards the equatorial low.
TranspirationThe process by which water in plants is transferred into water vapor in the atmosphere. Evaporation of water through the leaves of plants.
Transportation sectorConsists of private and public passenger and freight transportation, as well as government transportation, including military operations.
tree ringsa pattern observed in tree trunks, in which one band is usually equivalent to one year's growth.
Tropical Western Pacific (TWP) site(TWP)The second ARM research site, it is located in the south Pacific Ocean occupying Manus Island, Nauru Island, and Darwin, Australia.
TropopauseThe upper boundary of the troposphere, usually characterized by an abrupt change in lapse rate from positive (decreasing temperature with height) to…
TroposphereThe layer of the atmosphere closest to the Earth's surface.
TroughAn elongated area of relatively low atmospheric pressure, usually not associated with a closed circulation, and thus used to distinguish from a closed low.
TurbulenceIrregular motion of the atmosphere, as indicated by gusts and lulls in the wind.
ultraviolet radiation(UL-truh-VY-oh-let RAY-dee-AY-shun) Invisible rays that are part of the energy that comes from the sun.
Ultraviolet Radiation (UV)The energy range just beyond the violet end of the visible spectrum. Although ultraviolet radiation constitutes only about 5 percent of the total energy…
Unfinished oilsAll oils requiring further refinery processing, except those requiring only mechanical blending.
Unmanned Aerospace Vehicle (UAV) Program(UAV)A U.S. Department of Energy program that uses an unmanned aerospace vehicle and occupied aircraft to make key climate measurements that cannot be made my…
Unstable AirAir that is able to rise easily, and has the potential to produce clouds, rain, and thunderstorms.
Upper air observationUpper air observation An observation made in the free atmosphere either directly or indirectly.
Upper atmosphereUpper atmosphere The general term applied to the atmosphere above the mesopause.
Upper-air Weather ChartWeather maps that are produced for the portion of the atmosphere above the lower troposphere, generally at and above 850 mb.
UpwellingIn ocean dynamics, the upward motion of sub-surface water toward the surface of the ocean. This is often a source of cold, nutrient-rich water.
upwelling longwave irradianceThe rate at which radiant energy, at a wavelength longer than approximately 4 µm, is being emitted upwards into a radiation field and transferred across…
upwelling shortwave radianceThe rate at which radiant energy, at a wavelength between 0.4 and 4 µm, is being emitted upwards into a radiation field and transferred across a surface…
UTCBy international agreement, the local time at the prime meridian, which passes through Greenwich, England.
value-added product (VAP)(VAP)Physical models using ARM instrument data as inputs used to fulfill some of the unmet measurement needs of the ARM Program and to improve the quality of…
Vapor PressureThe partial pressure of water vapor in an air-water system.
varveannual layer of sediment deposited in an ocean or lake.
Vehicle miles traveled (VMT)One vehicle traveling the distance of one mile. Thus, total vehicle miles is the total mileage traveled by all vehicles.
Vertical VelocityThe component of velocity (motion) in the vertical. The evaluation of areas of upward vertical velocity is key to forecasting areas of active weather.
VirgaStreaks or wisps of precipitation falling from a cloud but evaporating before reaching the ground.
Virtual TemperatureThe virtual temperature is the temperature a parcel which contains no moisture would have to equal the density of a parcel at a specific temperature and…
VisibilityThe distance at which a given standard object can be seen and identified with the unaided eye
Visible LightElectromagnetic radiation from about 400 to 700 nm, which is detectable by the human eye.
visual stratigraphyprocess of identifying different layers in ice, rock, sediment, or other deposit, based on visually apparent distinctions such as color or other…
VortexA revolving mass of water (whirlpool) in which the streamlines are concentric circles and in which the total head is the same.
VorticityA measure of the rotation of air in a horizontal plane. Positive (counter-clockwise or cyclonic) vorticity can be correlated with surface low development…
Vostoksite in Antarctica (78°S, 106°E) where a 400,000 year long ice core was collected.
WakeThe region of turbulence immediately to the rear of a solid body caused by the flow of air over or around the body.
Warm FrontA transition zone between a mass of warm air and the colder air it is replacing.
WastewaterWater that typically contains less than 1% concentration of organic hazardous waste materials.
Water skyWater sky The dark appearance of the underside of a cloud layer when it is over a surface of open water.