Science — page 113 of 132

13,110 terms including subtopics (0 terms filed directly here)

Science terms

Spile (forepole) A plank driven ahead of a tunnel face for roof support.
Spill The accidental release of radioactive materials.
Spill light Light that falls outside of the area intended to be lighted.
Spills Water releases that cannot be put to use for project purposes (includes floodflows).
Spillway A passage for surplus water to flow over or around a dam.
Spillway channel An open channel or conduit conveying water from the spillway inlet downstream.
Spillway chute A steeply sloping spillway channel that conveys discharges at super-critical velocities.
Spillway Crest The lowest level at which water can flow over or through a spillway.
Spin-Up Slang for a small-scale vortex initiation, such as what may be seen when a gustnado, landspout, or suction vortex forms.
spindle An intracellular fibrous structure, involved in the control of chromosome movement in mitosis and meiosis.
Spinning Reserve Electric power provider capacity on line and running at low power in excess of actual load.
Spinning reserves Available capacity of generating facilities synchronized to the interconnected electric system where it can be called upon for immediate use in response…
SPIRIT As opposed to a ghost (see above), a spirit is normally the soul of the deceased that has crossed over, and exists in a spiritual or metaphysical plane.
SPKL Sprinkle
Splice site Location in the DNA sequence where RNA removes the noncoding areas to form a continuous gene transcript for translation into a protein.
spliceosome A complex of small nuclear ribonucleoproteins and other proteins that assemble on an immature mRNA and catalyse the excision of an intron. See: splicing.
Splicing 1. During the maturation of eukaryotic mRNA, the process that removes intron sequences and covalently joins exon sequences. Synonym: editing. 2.
splicing junction The DNA sequence immediately surrounding the boundary between an exon and an intron.
Split Flow A flow pattern high in the atmosphere characterized by diverging winds. Storms moving along in this type of flow pattern usually weaken.
split gene In eukaryotes, the encoding DNA of many structural genes is made up of exons and introns .
Split Spectrum Photovoltaic Cell A photovoltaic device where incident sunlight is split into different spectral regions, with an optical apparatus, that are directed to individual…
Split System Air Conditioner An air conditioning system that comes in two to five pieces: one piece contains the compressor, condenser, and a fan; the others have an evaporator and a…
Splitter wall A wall or pier parallel to the direction of flow in a channel that separates flows released from different sources as a means of energy dissipation.
Splitting Storm A thunderstorm which splits into two storms which follow diverging paths (a left mover and a right mover).
SPLNS Southern Plains
Spoil Dirt or rock which has been removed from its original location. Excavated material.
spontaneous mutation A mutation occurring in the absence of any known mutagen.
Sporadic cancer Cancer that occurs randomly and is not inherited from parents. Caused by DNA changes in one cell that grows and divides, spreading throughout the body.
Sporadic E In solar-terrestrial terms, a phenomenon occurring in the E region of the ionosphere, which significantly affects HF radiowave propagation.
sporangium (pl.: sporangia) A reproductive structure in plants that produces spores. A megasporangium produces megaspores, which give rise to the female gametophyte…
Spore A term used to describe a particle in plants, bacteria and fungi.
spore mother cell Synonym of sporocyte.
sporocyte A diploid germ line cell that is the parent of the four haploid spores generated by meiosis.
sporophyll A leaf that bears sporangia.
sporophyte The diploid generation in the life cycle of a plant, and that produces haploid spores by meiosis.
sport An individual plant, or portion thereof, showing a recognizably different phenotype from the parent, presumably as a result of spontaneous mutation.
Spot market Commodities and foreign currencies are traded for immediate delivery and payment on the spot market, also known as a cash market.
SPOTNIL In solar-terrestrial terms, a spotless disk.
Spotted owl habitat Dispersal habitat: Forest vegetation with at least 40% canopy closure and an average stand diameter of 11".
Spotting Outbreak of secondary fires as firebrands or other burning materials are carried ahead of the main fire line by winds.
Sprawl Development patterns where rural land is converted to urban/suburban uses more quickly than needed to house new residents and support new businesses, and…
Spray An ensemble of water droplets torn by the wind from an extensive body of water, generally from the crests of waves, and carried up into the air in such…
Spray Pyrolysis A deposition process whereby heat is used to break molecules into elemental sources that are then spray deposited on a substrate.
SPRD Spread
Spread trading Buying one instrument/commodity and selling another, with a view to profiting from the change in the gap between the two markets.
Spreader Stocker A type of furnace in which fuel is spread, automatically or mechanically, across the furnace grate.
Spreader stoker furnace A furnace in which fuel is automatically or mechanically spread. Part of the fuel is burned in suspension. Large pieces fall on a grate.
Spring The point at which the water table meets Earth's surface, causing water to flow from the ground.
Spring equinox Spring equinox See equinox.
Spring Tide A tide higher than normal which occurs around the time of the new and full moon.
Springline An imaginary horizontal reference line located at midheight, or halfway point, of a circular conduit, pipe, tunnel, or the point at which the side walls…
Sprinkler irrigation A method of irrigation in which the water is sprayed, or sprinkled, through the air to the ground surface.
Sprinkler system Consists of pipelines which carry water under pressure from a pump or elevated source to lateral lines along which sprinkler heads are spaced at…
SPS Severe Weather Potential Statement
Sputtering A process used to apply photovoltaic semi-conductor material to a substrate by a physical vapor deposition process where high-energy ions are used to…
SQLN Squall Line
Squall A strong wind characterized by a sudden onset in which the wind speed increases at least 16 knots and is sustained at 22 knots or more for at least one…
Squall Line A line of active thunderstorms, either continuous or with breaks, including contiguous precipitation areas resulting from the existence of the…
Square Wave Inverter A type of inverter that produces square wave output.; consists of a DC source, four switches, and the load.
Squirrel Cage Motor This 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…
SRH Storm-Relative Helicity
SRN Southern
SS Southshore
ssDNA Abbreviation for single-stranded DNA.
SSHS Saffir/Simpson Hurricane Scale
SSR Abbreviation for simple sequence repeat. See: microsatellite.
SST Sea Surface Temperature
ST Stratus
St Lawrence Freeze-Up Outlook A National Weather Service forecast product to keep mariners informed of the projected freeze-up date of ice the St. Lawrence River.
St. Elmo's Fire The glow on a masthead produced by an extreme buildup of electrical charge. Unprotected mariners should immediately move to shelter when this phenomena…
stability Tendency of systems, especially ecosystems, to persist, relatively unchanged, through time; also, persistence of a component of a system.
Stability Index The overall stability or instability of a sounding is sometimes conveniently expressed in the form of a single numerical value.
Stable Non-radioactive.
Stable air mass Stable 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 Layer The 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 Core Post-sunrise, elevated remnant of the temperature inversion that has built up overnight within a valley.
stable isotope different species of an element that have the same atomic number, but different atomic mass, that are not affected by radioactive decay.
stable state a steady condition in which the recently observed behavior is expected to continue unchanged in the future.
Staccato Lightning A Cloud to Ground (CG) lightning discharge which appears as a single very bright, short-duration stroke, often with considerable branching.
Stack A group of 20 roulette chips.
Stack (Heat) Loss Sensible and latent heat contained in combustion gases and vapor emitted to the atmosphere.
stacked genes Refers 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 effect The tendency of the sunlight to electricity conversion efficiency of amorphous silicon photovoltaic devices to degrade (drop) upon initial exposure to…
Staff Gage A vertical staff graduated in appropriate units which is placed so that a portion of the gage is in the water at all times.
Staff gauge A graduated scale on a plank or metal plate used to indicate the height of the water in a canal.
Stage The 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 Processing The first level of precipitation processing, occurring within the WSR-88D computer and performed for each volume scan of the radar.
Stage II Precipitation Processing The second level of precipitation processing, occurring within the WFO Advanced Weather Interactive Processing System (AWIPS) and performed on an hourly…
Stage III Precipitation Processing The third level of precipitation processing, performed interactively at RFCs. Stage II precipitation estimates from multiple radars are mosaiced into an…
Stage IV Precipitation Processing The fourth level of precipitation processing, performed automatically and/or interactively at NCEP.
stages of culture (I-IV) See: micropropagation.
staggered cuts Symmetrically cleaved phosphodiester bonds that lie on both strands of double-stranded DNA, but are not opposite one another.
staging area A designated area where construction equipment is temporarily stored (usually only during the construction phase).
Stagnation Temperature A condition that can occur in a solar collector if the working fluid does not circulate when sun is shining on the collector.
Stair Stepping The process of continually updating river forecasts for the purpose of incorporating the effects rain that has fallen since the previous forecast was…
Stakeholder A person or group of people who are involved in a project and feel ownership.
Stall In reference to a wind turbine, a condition when the rotor stops turning.
stamen Floral structure made up of an anther and a filament. The stamen is the male organ of a flower.
Stand To decline additional cards and keep your existing total.