Science terms starting with S

1,372 terms

  1. Specific Heat Capacity The quantity of heat required to change the temperature of one unit weight of a material by one degree.
  2. Specific Humidity The weight of water vapor, per unit weight of dry air.
  3. Specific Volume The volume of a unit weight of a substance at a specific temperature and pressure.
  4. Specific weight The weight per unit volume.
  5. Specific work work output -------------- mass flow
  6. Specific Yield The ratio of the water which will drain freely from the material to the total volume of the aquifer formation.
  7. specificity When referring to a medical test, specificity refers to the percentage of people who test negative for a specific disease among a group of people who do…
  8. Spectra A range of different measurements. In terms of physics, spectra usually refers to the different wavelengths, or colors (if in the visible range) of light…
  9. Spectral Density A radar term for the distribution of power by frequency.
  10. Spectral Energy Distribution A curve illustrating the variation or spectral irradiance with wavelength.
  11. Spectral Irradiance The monochromatic irradiance of a surface per unit bandwidth at a particular wavelength, usually expressed in Watts per square meter-nanometer bandwidth.
  12. Spectral karyotype (SKY) A visualization of all of an organism's chromosomes together, each labeled with a different color.
  13. Spectral Line An emission (bright) or absorption (dark) of light at a specific frequency or wavelength.
  14. Spectral Reflectance The ratio of energy reflected from a surface in a given waveband to the energy incident in that waveband.
  15. Spectral Wave Density On a buoy report, energy in (meter*meter)/Hz, for each frequency bin (typically from 0.03 Hz to 0.40 Hz).
  16. Spectral Wave Direction On a buoy report, mean wave direction, in degrees from true North, for each frequency bin.
  17. spectral width A measure of the spread of the Doppler spectrum and consequently is sensitive to the spread in the particle size spectra.
  18. Spectrally Selective Coatings A type of window glazing films used to block the infrared (heat) portion of the solar spectrum but admit a higher portion of visible light.
  19. Spectrograph A device that separates light by wavelength (color) in order to produce a spectrum that allows for the identification of elements within the light source.
  20. Spectrum Electromagnetic radiation arranged in order of wavelength from Ion wavelength radio waves to short wavelength gamma rays.
  21. Spectrum intensity The integral of the pseudo-velocity response spectrum taken over the range of significant structural vibration periods of the structure being analyzed.
  22. Spectrum Width This WSR-88D radar product depicts a full 360 degree sweep of spectrum width data indicating a measure of velocity dispersion within the radar sample…
  23. Spectrum Width Cross Section This WSR-88D radar product displays a vertical cross section of spectrum width on a grid with heights up to 70,000 feet on the vertical axis and distance…
  24. Specular reflection Also known as direct reflection, regular reflection, or mirror reflection. The reflection of electromagnetic rays without scattering or diffusion.
  25. Speed Shear The component of wind shear which is due to a change in wind speed with height, e.g.
  26. speleothem a mineral deposit formed in caves. Two types of speleothems are stalagmites and stalactites.
  27. SPENES NESDIS Satellite Precipitation Estimates
  28. spent medium After sub-culture, medium which is discarded because it has been depleted of nutrients, dehydrated, or accumulated toxic metabolic products.
  29. sperm Abbreviation for spermatozoon.
  30. sperm competition Competition between different spermatozoa to fertilize the of a single female.
  31. sperm sexing The separation of mammalian sperm into those bearing an X chromosome and those bearing a Y chromosome, in order to be able to produce, via artificial…
  32. spermatid Immature spermatozoon. One of the four cells formed at the end of the second meiotic division in spermatogenesis.
  33. spermatocyte The premeiotic parental cell of the spermatids; the primary spermatocyte before the initiation of the first meiotic division; the secondary spermatocyte…
  34. spermatogenesis The series of cell divisions in the testis as a result of which the formation and the maturation of the male gametes (i.e. sperm) are achieved.
  35. spermatogonium (pl.: spermatogonia) Primordial male germ cell. These can either divide by mitosis to produce daughter cells, or enter a growth phase and differentiate…
  36. spermatozoon (Abbreviation: sperm). (pl.: spermatozoa) The mature, mobile gametic cell of male animals, produced in the testis.
  37. spharoblast Nodule of wood which can give rise to adventitious shoots with juvenile characteristics.
  38. Sphere Calibration Reflectivity calibration of a radar by pointing the dish at a metal sphere of (theoretically) known reflectivity.
  39. spheroplast (AlteRNA tive spelling: sphaeroplast). A microbial or plant cell from which most of the cell wall has been removed, usually by enzymatic treatment.
  40. Spigot The plain end of a cast-iron pipe. The spigot is inserted into the bell end of the next pipe to make a water tight joint.
  41. spike 1. An inflorescence in which the main axis is elongated and the flowers are sessile. 2.
  42. spikelet The unit of inflorescence in grasses, made up of a small group of florets.
  43. Spile (forepole) A plank driven ahead of a tunnel face for roof support.
  44. Spill The accidental release of radioactive materials.
  45. Spill light Light that falls outside of the area intended to be lighted.
  46. Spills Water releases that cannot be put to use for project purposes (includes floodflows).
  47. Spillway A passage for surplus water to flow over or around a dam.
  48. Spillway channel An open channel or conduit conveying water from the spillway inlet downstream.
  49. Spillway chute A steeply sloping spillway channel that conveys discharges at super-critical velocities.
  50. Spillway Crest The lowest level at which water can flow over or through a spillway.
  51. Spin-Up Slang for a small-scale vortex initiation, such as what may be seen when a gustnado, landspout, or suction vortex forms.
  52. spindle An intracellular fibrous structure, involved in the control of chromosome movement in mitosis and meiosis.
  53. Spinning Reserve Electric power provider capacity on line and running at low power in excess of actual load.
  54. Spinning reserves Available capacity of generating facilities synchronized to the interconnected electric system where it can be called upon for immediate use in response…
  55. 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.
  56. SPKL Sprinkle
  57. Splice site Location in the DNA sequence where RNA removes the noncoding areas to form a continuous gene transcript for translation into a protein.
  58. 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.
  59. Splicing 1. During the maturation of eukaryotic mRNA, the process that removes intron sequences and covalently joins exon sequences. Synonym: editing. 2.
  60. splicing junction The DNA sequence immediately surrounding the boundary between an exon and an intron.
  61. Split Flow A flow pattern high in the atmosphere characterized by diverging winds. Storms moving along in this type of flow pattern usually weaken.
  62. split gene In eukaryotes, the encoding DNA of many structural genes is made up of exons and introns .
  63. 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…
  64. 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…
  65. 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.
  66. Splitting Storm A thunderstorm which splits into two storms which follow diverging paths (a left mover and a right mover).
  67. SPLNS Southern Plains
  68. Spoil Dirt or rock which has been removed from its original location. Excavated material.
  69. spontaneous mutation A mutation occurring in the absence of any known mutagen.
  70. 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.
  71. Sporadic E In solar-terrestrial terms, a phenomenon occurring in the E region of the ionosphere, which significantly affects HF radiowave propagation.
  72. sporangium (pl.: sporangia) A reproductive structure in plants that produces spores. A megasporangium produces megaspores, which give rise to the female gametophyte…
  73. Spore A term used to describe a particle in plants, bacteria and fungi.
  74. spore mother cell Synonym of sporocyte.
  75. sporocyte A diploid germ line cell that is the parent of the four haploid spores generated by meiosis.
  76. sporophyll A leaf that bears sporangia.
  77. sporophyte The diploid generation in the life cycle of a plant, and that produces haploid spores by meiosis.
  78. sport An individual plant, or portion thereof, showing a recognizably different phenotype from the parent, presumably as a result of spontaneous mutation.
  79. Spot market Commodities and foreign currencies are traded for immediate delivery and payment on the spot market, also known as a cash market.
  80. SPOTNIL In solar-terrestrial terms, a spotless disk.
  81. Spotted owl habitat Dispersal habitat: Forest vegetation with at least 40% canopy closure and an average stand diameter of 11".
  82. Spotting Outbreak of secondary fires as firebrands or other burning materials are carried ahead of the main fire line by winds.
  83. 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…
  84. 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…
  85. Spray Pyrolysis A deposition process whereby heat is used to break molecules into elemental sources that are then spray deposited on a substrate.
  86. SPRD Spread
  87. Spread trading Buying one instrument/commodity and selling another, with a view to profiting from the change in the gap between the two markets.
  88. Spreader Stocker A type of furnace in which fuel is spread, automatically or mechanically, across the furnace grate.
  89. 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.
  90. Spring The point at which the water table meets Earth's surface, causing water to flow from the ground.
  91. Spring equinox Spring equinox See equinox.
  92. Spring Tide A tide higher than normal which occurs around the time of the new and full moon.
  93. 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…
  94. Sprinkler irrigation A method of irrigation in which the water is sprayed, or sprinkled, through the air to the ground surface.
  95. 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…
  96. SPS Severe Weather Potential Statement
  97. 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…
  98. SQLN Squall Line
  99. 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…
  100. Squall Line A line of active thunderstorms, either continuous or with breaks, including contiguous precipitation areas resulting from the existence of the…