Square Wave InverterA type of inverter that produces square wave output.; consists of a DC source, four switches, and the load.
Squirrel Cage MotorThis is another name for an induction motor. The motors consist of a rotor inside a stator.
SRF(Surf Zone Forecast) - A National Weather Service routine or event driven forecast product geared toward non-boating marine users issued for an area…
St Lawrence Freeze-Up OutlookA National Weather Service forecast product to keep mariners informed of the projected freeze-up date of ice the St. Lawrence River.
St. Elmo's FireThe glow on a masthead produced by an extreme buildup of electrical charge. Unprotected mariners should immediately move to shelter when this phenomena…
stabilityTendency of systems, especially ecosystems, to persist, relatively unchanged, through time; also, persistence of a component of a system.
Stability IndexThe overall stability or instability of a sounding is sometimes conveniently expressed in the form of a single numerical value.
Stable air massStable air mass Air mass having static stability in its lower layers; it is free from convection, has a low degree of turbulence and may have stratiform…
Stable Boundary LayerThe stably-stratified layer that forms at the surface and grows upward, usually at night or in winter, as heat is extracted from the atmosphere's base in…
Stable CorePost-sunrise, elevated remnant of the temperature inversion that has built up overnight within a valley.
stable isotopedifferent species of an element that have the same atomic number, but different atomic mass, that are not affected by radioactive decay.
stable statea steady condition in which the recently observed behavior is expected to continue unchanged in the future.
Staccato LightningA Cloud to Ground (CG) lightning discharge which appears as a single very bright, short-duration stroke, often with considerable branching.
Stack (Heat) LossSensible and latent heat contained in combustion gases and vapor emitted to the atmosphere.
stacked genesRefers to the insertion of two or more genes into the genome of an organism. An example would be a plant carrying a giving insect resistance, and a bar…
Staebler-Wronski effectThe tendency of the sunlight to electricity conversion efficiency of amorphous silicon photovoltaic devices to degrade (drop) upon initial exposure to…
Staff GageA vertical staff graduated in appropriate units which is placed so that a portion of the gage is in the water at all times.
Staff gaugeA graduated scale on a plank or metal plate used to indicate the height of the water in a canal.
StageThe extent of a cancer in the body. Staging is usually based on the size of the tumor, whether lymph nodes contain cancer, and whether the cancer has…
Stage I Precipitation ProcessingThe first level of precipitation processing, occurring within the WSR-88D computer and performed for each volume scan of the radar.
Stage II Precipitation ProcessingThe second level of precipitation processing, occurring within the WFO Advanced Weather Interactive Processing System (AWIPS) and performed on an hourly…
Stage III Precipitation ProcessingThe third level of precipitation processing, performed interactively at RFCs. Stage II precipitation estimates from multiple radars are mosaiced into an…
Stage IV Precipitation ProcessingThe fourth level of precipitation processing, performed automatically and/or interactively at NCEP.
staggered cutsSymmetrically cleaved phosphodiester bonds that lie on both strands of double-stranded DNA, but are not opposite one another.
staging areaA designated area where construction equipment is temporarily stored (usually only during the construction phase).
Stagnation TemperatureA condition that can occur in a solar collector if the working fluid does not circulate when sun is shining on the collector.
Stair SteppingThe process of continually updating river forecasts for the purpose of incorporating the effects rain that has fallen since the previous forecast was…
StakeholderA person or group of people who are involved in a project and feel ownership.
StallIn reference to a wind turbine, a condition when the rotor stops turning.
stamenFloral structure made up of an anther and a filament. The stamen is the male organ of a flower.
StandTo decline additional cards and keep your existing total.
Stand conversionThe conversion of a noncommercial stand of timber to a commercial stand.
Stand densityThe number or mass of trees occupying a site. It is usually measured in terms of stand density index or basal area per acre.
Stand-Alone GeneratorA power source/generator that operates independently of or is not connected to an electric transmission and distribution network; used to meet a load(s)…
Stand-Alone InverterAn inverter that operates independent of or is not connected to an electric transmission and distribution network.
Stand-Alone SystemAn system that operates independent of or is not connected to an electric transmission and distribution network.
Stand-by Heat LosesA term used to describe heat energy lost from a water heater tank.
Stand-By PowerFor the consumer, this is the electricity that is used by your TVs, stereos, and other electronic devices that use remote controls.
Standard AirAir with a weight of 0.075 pounds per cubic foot with an equivalent density of dry air at a temperature of 86 degrees Fahrenheit and standard barometric…
Standard AtmosphereA hypothetical vertical distribution of atmospheric temperature, pressure, and density that, by international agreement, is taken to be representative of…
Standard CandleA celestial object whose intrinsic brightness is known or can be estimated by some physical principle.
Standard ConditionsIn refrigeration, an evaporating temperature of 5 degrees Fahrenheit (F), a condensing temperature of 86 degrees F.
Standard Cubic FootA column of gas at standard conditions of temperature and pressure (32 degrees Fahrenheit and one atmosphere).
Standard deviationStandard deviation is a statistical measurement of how far a variable quantity, such as the price of a stock, moves above or below its average value.
standard errorThe standard error of an estimate is a measure of the sampling variability of the estimate.
Standard Synoptic TimesThe times of 0000, 0600, 1200, and 1800 UTC. Also known as the main synoptic times.
Standards and guidelinesBounds or constraints within which all practices in a given area will be carried out, in achieving the goals and objectives for that area.
Standby reservesUnused capacity in an electric system in machines that are not in operation but that are available for immediate use if required.
Standing Operating Procedures (SOP)A comprehensive single-source document covering all aspects of dam and reservoir operation and maintenance and emergency procedures.
StandpipePipe or tank connected to a closed conduit and extending to or above the hydraulic grade line of the conduit to afford relief from surges of pressure in…
starchA substance found in plants. It contains sugar molecules joined chemically. It is found in high levels in foods such as potatoes, rice, corn, and wheat.
StarLinkTMAn insect-resistant variety of corn that was approved for animal feed only, not labeled for human consumption.
start codonThe codon which specifies the first amino acid of a polypeptide chain and at which the ribosome starts the process of translation.
Starting SurgePower, often above an appliance's rated wattage, required to bring any appliance with a motor up to operating speed.
Starting TorqueThe torque at the bottom of a speed (rpm) versus torque curve. The torque developed by the motor is a percentage of the full-load or rated torque.
State Emergency Response Commission (SERC)Appointed by the governor of each state for the designation of emergency planning districts, appoint LEPC's, supervise and coordinate their activities…
State Forecast ProductThis National Weather Service product is intended to give a good general picture of what weather may be expected in the state during the next 5 days.
State Historic Preservation Officer (SHPO)The State officer charged with the identification and protection of prehistoric and historic resources in accordance with the National Historic…
State Implementation Plan (SIP)A state plan required by the Clean Air Act to bring nonattainment areas into compliance with federal ambient air quality standards.
State organizationThe State government agency or office having the principal or lead role in emergency planning and preparedness.
State Tax IncentivesMassachusetts offers tax incentives to individuals and business that install renewable energy systems at their homes or offices.
State Weather RoundupThis is a National Weather Service tabular product which provides routine hourly observations within the state through the National Weather Wire Service…
Static headThe difference in elevation between the pumping source and the point of delivery. The vertical distance between two points in a fluid.
Static PressureThe force per unit area acting on the surface of a solid boundary parallel to the flow.
StationAny one of a series of stakes or points indicating distance from a point of beginning or reference.
Station IDFive-digit WMO Station Identifier used by the Buoy Data Center since 1976. ID's can be reassigned to future deployments within the same 1 degree square.
Station ModelA specified pattern for plotting, on a weather map, the meteorological symbols that represent the state of the weather at a particular observing station.
Station PressureThe absolute air pressure at a given reporting station. The air pressure is directly proportional to the combined weight of all air in the atmosphere…
Station useEnergy used in a generating plant as necessary in production of electricity. Includes energy consumed for plant light, power, and auxiliaries regardless…
Stationary FrontA front between warm and cold air masses that is moving very slowly or not at all.
Stationary phaseThe plateau of the growth curve after log growth, during which cell number remains constant. New cells are produced at the same rate as older cells die.
stationary pressureA front between warm and cold air masses that is moving very slowly or not at all.
Stationary white noiseRandom energy with statistical characteristics that do not vary with time.
StatorThat portion of a machine which contains the stationary (non-moving) parts that surround the moving parts (rotor).
Stator windingsThe armature or stationary winding of a synchronous generator.
Steady flowFlow in an open channel is said to be steady if the depth of flow does not change over a given time interval. No change occurs with repect to time.
steady stateIn a continuous fermentation process, the condition under which the number of cells removed with the outflow is exactly balanced by the number of newly…
Steady state conditionWhen model input values are nearly constant for a defined period of time.
Steady State TheoryA cosmological model where matter is created constantly as the universe expands so it remains homogenous and isotropic.
SteamWater in vapor form; used as the working fluid in steam turbines and heating systems.
Steam amendment chemicalsChemicals used to treat raw water to remove certain chemical species, thus amending its hardness or pH, making it suitable for use in a steam cycle.
Steam BoilerA type of furnace in which fuel is burned and the heat is used to produce steam.