| Section S | S index | 1141-1149 of 1376 terms |
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subhumid climateA humidity province of Thornthwaite's 1931 climate classification, defined by precipitation-effectiveness index values of 32–63, and designated letter code C. Based on its typical vegetation, the subhumid climate is sometimes called grassland, or prairie, climate. In 1948, Thornthwaite divided this category into moist subhumid and dry subhumid climate, with moisture index values of 0 to +20 and -20 to 0, respectively. The zero value of moisture index also divides, overall, the moist climates from the dry climates. This type of climate and the semiarid climate are very susceptible to drought conditions.
Thornthwaite, C. W., 1931: The climates of North America according to a new classification. Geogr. Rev., 21, 633–655.
Thornthwaite, C. W., 1948: An approach toward a rational classification of climate. Geogr. Rev., 38, 55–94.
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subjective forecastA forecast based on decisions made by an individual. Conversely, an objective forecast is based solely on the results from a set of mathematical equations or numerical model.
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sublimation nucleus(Obsolete.) Any particle upon which an ice crystal may grow by the process of sublimation. A. Wegener (1911) was the first to suggest that the atmosphere might contain nuclei upon which sublimation (deposition) of water vapor directly to ice occurs in a manner similar to condensation upon condensation nuclei. In experiments where various nuclei are added to supercooled clouds, it is generally difficult to determine whether these nuclei function as deposition nuclei or as freezing nuclei. It has never been demonstrated that natural deposition nuclei (as distinguished from freezing nuclei) exist in the atmosphere. In the laboratory, cases of artificial preparation of true sublimation nuclei have been reported that activate ice crystals without reaching anywhere close to water saturation; lack of such nuclei in the atmosphere results from the predominance of mixed nuclei.
Wegener, A., 1911: Thermodynamik der Atmosphäre, Barth, Leipzig
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sublimation of iceThe change of phase of water from solid to gas without passing through the liquid phase.
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sublimationThe process of phase transition from solid directly to vapor in the absence of melting. Thus an ice crystal or icicle sublimes under low relative humidity at temperatures below 0°C. The process is analogous to evaporation of a liquid. Colloquially the terms are used interchangeably for the solid–vapor transition (evaporation). For growth, the term sublimation has been replaced by deposition since the 1970s. There is evidence that deposition nucleation does occur, although there may be an adsorbed layer prior to nucleation. It appears that most nuclei in the atmosphere require near–water saturation before they initiate ice.
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submesoscale coherent vortices(Abbreviated SCV.) Isolated, long-lived eddies, having spatial scales smaller than mesoscale eddies; usually anticyclonic, having a geopotential maximum and stratification minimum in the center, with a velocity field having an interior maximum. SCV types include thermocline SCVs, subthermocline SCVs, Meddies, Arctic Ocean SCVs, and others.
McWilliams, J. C., 1985: Submesoscale, coherent vortices in the ocean. Rev. Geophys., 23, 165–182.
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suborbital trackVertical projection of the actual flight path of an aerial or space vehicle onto the surface of the earth or other body. See ground track.
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