| Section S | S index | 11-19 of 1376 terms |
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sailing directions—A descriptive book for the use of mariners, containing detailed information on a wide variety of material important to navigators of coastal and intracoastal waters. Most of this information cannot be shown graphically on the standard nautical charts and is not readily available elsewhere. This information includes navigation regulations, outstanding landmarks, channel and anchorage peculiarities, dangers, weather, ice, currents, and port facilities. They are compiled and issued by national hydrographic authorities. For waters of the United States and its possessions, sailing directions are published by the National Ocean Service and are called United States Coast Pilots.
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salinity—A measure of the quantity of dissolved salts in seawater. It is formally defined as the total amount of dissolved solids in seawater in parts per thousand (0/00) by weight when all the carbonate has been converted to oxide, the bromide and iodide to chloride, and all organic matter is completely oxidized. These qualifications result from the chemical difficulty in drying the salts in seawater. In practice, salinity is not determined directly but is computed from chlorinity, electrical conductivity, refractive index, or some other property with a relationship to salinity that is well established. The relationship between chlorinity Cl and salinity S as set forth in Knudsen's tables is  In 1940, however, a better expression for the relationship between total dissolved salts Σ and chlorinity was found to be  In more recent times, with the advent of devices that measure continuous records of conductivity electronically (e.g., CTD or conductivity–temperature–depth profiler), a new “practical salinity scale” has been determined. It is defined in terms of its electrical conductivity relative to a prescribed standard and it is given the units psu, for “practical salinity units.” For most purposes one can assume that the new unit, psu, and the older unit, 0/00, are synonymous.
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salt content—Concentration of dissolved salts in a body of water.
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salt fingering—A form of double-diffusive convection that occurs when warm, salty water overlies cold freshwater. A parcel of freshwater moved upward will gain heat more quickly than it gains salt and so will become lighter than the surrounding water. It will rise unstably as a result. Salt fingering has been observed in the Caribbean Sea where it gives rise to stable layers hundreds of kilometers in extent. The process transports salt much more efficiently than heat. See also Turner angle.
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salt haze—A haze created by the presence of finely divided particles of sea salt in the air, usually derived from the evaporation of sea spray.
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