SURFACE TEMPERATURE 



subphyluiti — See classification of organisms. 



subsequent penetration — The depth to which a 

 mine sinks into the bottom after the initial 

 impact. 



subsurface current — A current usually flowing 

 below the thermocline, generally at slower 

 speeds and frequently in a ditl'erent direction 

 from the currents near tlie surface. 



subtropical anticyclone — See subtropical high. 



Subtropical Convergence — (or Subtropical Con- 

 vergen-re zone, Svbf)'opical Convergence line). 

 The zone of converging currents generally lo- 

 cated in midlatitudes. It is fairly well defined 

 in the Soutliern Hemisphere where it appears as 

 an earth-girding region within which the sur- 

 face temjDerature increases equatorward. 



Subtropical Convergence line — See Subtropical 

 Convergence. 



Subtropical Convergence zone — See Subtropi- 

 cal Convergence. 



subtropical high — ^(or subtropical anticyclone, 

 oceanic anticyclone, oceanic high). One of the 

 semipermanent highs of the subtropical high 

 pressure belt. They lie over oceans, and are 

 best developed in the summer season. See 

 Azores high, Bermuda high, Pacific high. ( 5 ) 



sugar berg — See sugar iceberg. 



sugar iceberg — (or sugar berg). An iceberg 

 composed of the more porous type of glacier ice. 

 Such ice is formed at very low temperatures, is 

 loosely constructed, and falls apart easily. (&5) 



sugarloaf sea — See intersecting waves. 



summer minimum — The scarcity of phytoplank- 

 ton (generally diatoms) noted after the abund- 

 ance in the spring. Grazing by zooplankton 

 and depletion of essential nutrients are the main 

 factors in reducing the phytoplankton popu- 

 lation. 



summer solstice — For either hemisphere, the 

 solstice at which the sun is above that hemi- 

 sphere. In northern latitudes, tliis occurs 

 approximately on 21 June. (5) 



sun zenith distance — The angle between the 

 zenith and the sun's disk. (8) 



superfamily — See classification of organisms. 



superoceanic deep — See hadal. 



supralittoral — (or supraticlal) . The shore zone 

 immediately above high tide level, commonly the 

 zone kept more or less moist by waves and spray. 

 (2) {See figure for classification of marine 

 environments.) 



supratidal — See supralittoral. 



surf — 1. Collective term for breakers. (73) 

 2. Tlie wave activity in the area between the 

 shoreline and the outermost limit of breakers. 

 (61) 



surface anomalies — Irregularities at the earth's 

 surface, in the weathering zone, or in near sur- 

 face beds which interfere with geophysical 

 measurements! 



surface corrections — Corrections of geophysical 

 measurements for surface anomalies and 



ground elevations. 



surface current — A general term meaning that 

 part of a directly observed movement of water 

 which, in neai'shore areas, does not extend more 

 than 3 to 10 feet (1 to 3 meters) below the sur- 

 face; in deep, or open ocean areas, surface cur- 

 rents generally are considered to extend from 

 the surface to depths of about 33 feet (10 

 meters). 



When surface currents are computed by theo- 

 retical methods, the volume of water in the 

 mixed layer (above the thermocline) from the 

 surface to depths of about 165 to 495 feet (50 to 

 150 meters), generally is referred to as surface 

 current. 



surface density — The density of the surface ma- 

 terial within the range of elevation differences 

 of the gravitational survey. Both the Bouguer 

 correction and the terrain corrections depend 

 on the density of the surface materials. 



surface duct — A zone immediately below the 

 sea surface where sound rays are refracted to- 

 ward the surface and then reflected. They are 

 refracted because the sound velocity at some 

 depth near the surface is greater than at the 

 surface. 



The rays alternately are refracted and re- 

 flected along the duct to considerable distances 

 from the sound source. 



surface energy — Ses surface tension. 



surface free energy — See surface tension. 



surface of discontinuity — See interface. 



surface of no motion — See layer of no motion. 



surface path — (or direct path, near surface 

 path). Sound paths which go no deeper than 

 1,000 feet from the surface. 



surface probe — A thermistor that is towed 

 along the surface to record a continuous sea 

 surface temperature. 



surface reflection — The return of sound rays to 

 depth after striking the sea surface. 



surface reverberation — See reverberation. 



surface scattering layer — The population (s) of 

 organisms in the surface layers of the ocean 

 which scatter sound. The organisms may 

 occur in a uniform layer extending from the sur- 

 face to a depth as great as 100 fathoms. On the 

 echo-sounder record, several layers or patches 

 of discrete scatterers may be conspicuous within 

 the uniform layer. See deep scattering layer, 

 shallow scattering layer. 



surface temperature — 1. In oceanography, the 

 temperature of the layer of sea water nearest the 

 atmosphere. It is generally determined either 

 as bucket temperature or injection tempera- 

 ture. 



2. In meteorology, the temperature of the air 

 near the surface of the earth, almost invariably 



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