Science terms starting with S

1,372 terms

Site preparation Various treatments applied to a harvested area to promote regeneration of the site.
Site Specific Hydrologic Prediction System (SSHP) The WFO hydrologic forecast model for small rivers and streams that uses RFC soil moisture state variables, stage and precipitation data.
Site-directed mutagenesis The process of introducing spe- cific base-pair mutations into a gene.
Site-Specific A term used to describe any process or enzyme which acts at a defined sequence within a DNA or RNA molecule.
site-specific mutagenesis The induction of mutation s, by molecular biology techniques, in one or more specific nucleotide s within a defined coding sequence in order to create…
SITOR (SImplex Teletype Over Radio) - a means of transmitting text broadcasts over radio. The U.S.
sitosterol See: phytosterol.
six-base cutter Type II restriction endonucleases whose recognition site and cleavage site consist of a characteristic sequence of six nucleotide pairs.
Sizing The process of designing a solar system to meet a specified load given the solar resource and the nominal or rated energy output of the solar energy…
Skewed Tilted images. See De-skewing.
Skidder A self-propelled machine to transport harvested trees or logs from the stump area to the landing or work deck.
Skimmer gate A gate at the spillway crest whose prime purpose is to control the release of debris and logs with a limited amount of water.
Skin biopsy Process of removing tissue, in this case skin, from living patients for diagnostic examination, or the tissue specimen obtained by that process.
SKIP A non-digging bucket or tray that hoists material
Skirt (fan, dune) A sloping alluvial fan surface made of sediment deposited by a stream at the mouth of a canyon between a mountain and the adjacent alluvial valley floor.
Skiving To dig in thin layers.
sky brightness temperature A descriptive measure of radiation in terms of the temperature of a hypothetical black body emitting an identical amount of radiation at the same…
Sky Condition Used in a forecast to describes the predominant/average sky condition based upon octants (eighths) of the sky covered by opaque (not transparent) clouds.
Sky glow Brightening of the sky caused by outdoor lighting and natural atmospheric and celestial factors.
Skylight A window located on the roof of a structure to provide interior building spaces with natural daylight, warmth, and ventilation.
Skylining Siting of a structure on or near a ridge line so that it is silhouetted against the sky.
SKYWARN A nationwide network of volunteer weather spotters who report to and are trained by the National Weather Service.
SL Sea Level
Slab A concrete pad that sits on gravel or crushed rock, well-compacted soil either level with the ground or above the ground.
Slab on Grade A slab floor that sits directly on top of the surrounding ground.
Slaking The process of breaking up or sloughing when an indurated soil is immersed in water.
Slash The unmerchantable material left on site subsequent to harvesting a timber stand, including tops, limbs, cull sections.
Slate Fine-grained metamorphic rock formed by "baking" and recrystallizing shale or mudstone and which splits easily along flat, parallel planes.
SLD Solid
Sleet Precipitation that consists of clear pellets of ice; sleet is formed when raindrops fall through a layer of cold air and freeze.
Sleet Warning Issued when accumulation of sleet in excess of 1/2" is expected; this is a relatively rare scenario.
SLGT Slight
Slide A small landslide.
Slide gate A steel gate that upon opening or closing slides on its bearings in edge guide slots. A gate that can be opened or closed by sliding in supporting guides.
Slide Gate (Sluice Gate) A gate that can be opened or closed by sliding it in supporting guides.
Slight Chance In 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.
Sling Psychrometer An instrument used to measure the water vapor content of the atmosphere in which wet and dry bulb thermometers are mounted on a frame connected to a…
Slinky<sup>TM</sup> Ground Loop In this type of closed-loop, horizontal geothermal heat pump installation, the fluid-filled plastic heat exchanger pipes are coiled like a SlinkyTM to…
SLIP Motion occurring along a fault plane.
Slip rate The rate of motion obtained when the amount of offset is divided by a time interval.
SLO Slow
slope An inclined surface usually defined by the ratio of the horizontal distance to the vertical distance, i.e. 2:1 (2 horizontal units to 1 vertical unit).
Slope failure The downward and outward movement of a mass of rock or unconsolidated materials as a unit. Landslides and slumps are examples.
Slope Protection The protection of an embankment slope against wave action or erosion.
Slope stability The resistance of an inclined surface to failure by sliding or collapsing.
SLOSH (Sea, Lake and Overland Surges from Hurricanes) - A computer model run by the National Hurricane Center (NHC) to estimate storm surge heights resulting…
Slough A long, narrow stretch of water such as a small stream or feeder tributary off a lake or river.
Slow pyrolysis Thermal conversion of biomass to fuel by slow heating to less than 450°C in the absence of oxygen.
SLP Sea Level Pressure
SLT 1. Slight (as in "slight chance") 2. Sleet
Sludge The mixture of organic and inorganic substances separated from sewage.
Slug Large initial amount. A unit of mass which will undergo an acceleration of 1 foot per second squared when a force of 1 pound is applied to it.
Sluice An opening for releasing water from below the static head elevation.
Sluice gate A gate that can be opened or closed by sliding in supporting guides.
Sluiceway An opening in a diversion dam used to discharge heavy floating debris safely past the dam.
Sluicing A method of compacting soil where the soil is washed into placed with a high velocity stream of water.
Slurry Watery mixture of insoluble matter which is pumped beneath a dam to form an impervious barrier. Cement grout.
Slurry trench A narrow excavation whose sides are supported by a mud slurry filling the excavation. Sometimes used incorrectly to describe the cutoff itself.
SLY Southerly
SM service mark
SMA The Soil Moisture Accounting Model.
Small Craft There is no precise definition for small craft. Any vessel that may be adversely affected by Small Craft Advisory criteria should be considered a small…
Small Craft Advisory (SCA) - An advisory issued by coastal and Great Lakes Weather Forecast Offices (WFO) for areas included in the Coastal Waters Forecast or Nearshore Marine…
Small Craft Advisory for Hazardous Seas (SCAHS) - An advisory issued by coastal and Great Lakes Weather Forecast Offices (WFO).
Small Craft Advisory for Rough Bar (SCARB): An advisory issued by coastal and Great Lakes Weather Forecast Offices (WFO) for specialized areas near harbor or river entrances known as bars.
Small Craft Advisory for Winds (SCAW): An advisory issued by coastal and Great Lakes Weather Forecast Offices (WFO).
Small Craft Should Exercise Caution Precautionary statement issued to alert mariners with small, weather sensitive boats.
Small Hail Technically used to refer to snow pellets or graupel.
small nuclear ribonucleoprotein (Abbreviation: snRNP). A complex of small nuclear RNA and nuclear protein, heavily involved in the post-transcriptional processing of mRNA, especially the…
small nuclear RNA (Abbreviation: snRNA ). RNA transcripts of 100-300 bp that associate with proteins to form small nuclear ribonucleoprotein particles.
Small nuclear RNA (snRNA) Short RNA transcripts of 100-300 bp that associate with proteins to form small nuclear ribonucleoprotein particles (snRNPs), which participate in RNA…
Small power producer (SPP) Under the Public Utility Regulatory Policies Act (PURPA), a small power production facility (or small power producer) generates electricity using waste…
Small Scale Energy Loan Program (SELP) In Oregon, a low-cost loan and technical assistance program administered by the Oregon Department of Energy.
Small Stream Flooding Flooding of small creeks, streams, or runs.
Smart Energy Is the use of renewable resources to create electricity and to heat and cool buildings, as well as more efficient use of energy through conservation and…
Smart Growth Well-planned development that protects open space and farmland, revitalizes communities, keeps housing affordable and provides more transportation choices.
Smart Window A term used to describe a technologically advanced window system that contains glazing that can change or switch its optical qualities when a low voltage…
Smog A visible haze caused by particulate matter and ground-level ozone.
Smoke (abbrev. K) Smoke in various concentrations can cause significant problems for people with respiratory ailments.
Smoke Dispersal Describes the ability of the atmosphere to ventilate smoke. Depends on the stability and winds in the lower layers of the atmosphere, i.e.
Smoke Management The use of meteorology, fuel moisture, fuel loading, fire suppression and burn techniques to keep smoke impacts from prescribed fires within acceptable…
Smolts Adolescent salmon 3 to 7 inches long.
Smoothed Sunspot Number An average of 13 monthly RI numbers, centered on the month of concern.
SMW (Special Marine Warning) - A warning product issued for potentially hazardous weather conditions usually of short duration (up to 2 hours) producing…
SN snow
Snag Any standing dead, partially dead or defective tree. A hard snag is composed primarily of sound wood.
Snotel SNOw TELemetry - An automated network of snowpack data collection sites. The Natural Resources Conservation Service (NRCS), formerly the Soil Conservation…
Snow Precipitation that consists of frozen flakes formed when water vapor accumulates on ice crystals, going directly to the ice phase.
Snow Accumulation and Ablation Model A model which simulates snow pack accumulation, heat exchange at the air-snow interface, areal extent of snow cover, heat storage within the snow pack…
Snow Advisory This product is issued by the National Weather Service when a low pressure system produces snow that may cause significant inconveniences, but do not meet…
Snow blink Snow blink (snow sky) A bright white glare on the underside of clouds, produced by the reflection of light from snow-covered surface.
Snow Core A sample of either freshly fallen snow, or the combined old and new snow on the ground.
Snow Cornice A mass of snow or ice projecting over a mountain ridge.
Snow cover Snow cover 1) In general, a layer of snow on the ground surface. 2) The areal extent of snow-covered ground, usually expressed as per cent of total area…
Snow Density The mass of snow per unit volume which is equal to the water content of the snow divided by its depth.
Snow Depth The combined total depth of both the old and new snow on the ground.
Snow Flurries Snow flurries are an intermittent light snowfall of short duration (generally light snow showers) with no measurable accumulation (trace category).
Snow Grains Precipitation consisting of white, opaque ice particles usually less than 1 mm in diameter.
Snow Pack Same as Snowcover; the combined layers of snow and ice on the ground at any one time.