STREAM CURRENT 



stream current — A narrow, deep, and fast- 

 moving current as op20osed to a relatively wide 

 and weak drift current ; for example, the Gulf 

 Stream, the Kuroshio, and the Cromwell 

 Undercurrent. 



streamline flow — See laminar flow. 



strength of current — 1. The greatest speed of the 

 tidal current; usually referenced in knots and 

 in hours before or after low and high water. 

 {See figure for current ellipse.) 



2. For nontidal currents, the average of the 

 highest speeds observed, usually determined 

 from the highest 10 percent of the observations. 



strength of ebb — (also called ehi strength) . The 

 ebb current at the time of maximum speed. 



strength of ebb interval — The time interval be- 

 tween the transit (upper or lower) of the moon 

 and the next maximum ebb current at a place. 

 Usually shortened to ebb interval. (68) 



strength of flood — (also called food strength). 

 The flood current at the time of maximum 

 speed. 



strength of flood interval — The time interval be- 

 tween the transit (upper or lower) of the moon 

 and the next maximum flood current at a place. 

 Usually shortened to flood interval. (68) 



stress tensor — The complete set of stress compo- 

 nents in a medium, which are written as a ten- 

 sor Tij. It has nine components, one for each 

 of the coordinate faces of an imaginary fluid 

 element upon whicli the stress acts {j = x, y, z) 

 and for each direction in which the stress is 

 directed {i=x,y,3). ( 5 ) 



stridulatory sound — The noise produced by hard 

 skeletal parts of an animal rubbing together or 

 vibrating as the rasping of pharyngeal teeth in 

 certain fishes or the rattle of the spiny lobster's 

 antennae against a toothed ridge on the 

 carapace. 



string — See strip. 



strip — ( or !ce stream, we stnp, stream string) . A 

 long narrow area of pack ice, more limited than 

 a belt, bounded by open water or land. Strips 

 are usually about one kilometer (3,281 feet) or 

 less in width, and are composed of small frag- 

 ments detached from the main mass of ice run 

 togetlier under the influence of wind, swell, or 

 current. (74) 



Si constituent — The principal solar semidiurnal 

 constituent of the theoretical tide-producing 

 forces. {See figure for partial tide.) 



Subarctic Current — An eastward flowing ocean 

 current which lies north of the North Pacific 

 Current. It originates from part of the Aleu- 

 tian Current and from outflow of water from 

 the Bering Sea. As it approaches the coast of 

 North America it divides to join the northward- 

 flowing Alaska Current, and the southward- 

 flowing California Current. 



subbottom reflection — The return of sound 

 energy from a discontinuity in material below 

 the sea bottom surface. 



subclass — See classification of organisms. 



subcoastal plains — Submerged plains of a conti- 

 nental shelf. (2) 



subkingdom — See classification of organisms. 



sublimation — The transition of the solid phase of 

 certain substances into the gaseous and vice 

 versa without passing through the usual liquid 

 phase. Water possesses this property ; thus, ice 

 can change directly to water vapor or water 

 vapor to ice. Strictly speaking, the word sub- 

 limation means the evaporation of ice and its 

 immediate recondensation elsewhere, but it is 

 also used to denote the single process of the con- 

 densation of water vapor into ice. (65) 



sublittoral — That benthic region extending from 

 mean low water to a depth of about 100 fathoms 

 (200 meters) , or the edge of a continental shelf. 

 (2) {See figure for classification of marine 

 environments.) 



submarine alluvial fan — This term is not recom- 

 mended by the ACUF for a fan composed of 

 sedimentary deposits. See fan. 



submarine best depth — The optimum depth for 

 a submarine to operate to avoid detection. 



submarine bulge — See fan. 



submarine canyon — See canyon. 



submarine delta — See fan. 



submarine geology — See geological oceanog- 

 raphy. 



submarine geomorphology — The branch of geol- 

 ogj^ that deals with the features of the sea floor, 

 their form, origin, and development, and the 

 changes they are undergoing. 



submarine isthmus — A submarine elevation join- 

 ing two land regions and separating two basins 

 by a depth less than that of the basins. (68) 



submarine peninsula — An elevated portion of 

 the submarine relief resembling a peninsula. 

 The opposite is sac. (68) See peninsula. 



submarine pit — See submarine well. 



submarine valley — See valley. 



submarine well — A cavity on the sea bottom ; also 

 called a submarine jsit. (68) 



submerged breakwater — A breakwater with its 

 top below the still water level. When this 

 structure is struck by a wave part of the wave 

 energy is reflected seaward. The remaining 

 energy is largely dissipated in a breaker, trans- 

 mitted shoreward as a multiple crest system, or 

 transmitted shoreward as a simple wave system. 



suborder — See classification of organisms. 



subordinate station — 1. One of the places for 

 which tide or tidal current predictions are deter- 

 mined by applying a correction to tlie predic- 

 tions of a reference station. ( 68 ) 



2. A tide or tidal current station at which a 

 short series of observations has been made, which 

 are reduced by comparison with simultaneous ob- 

 servations at a reference station. (68) 



3. Called secondary port in British terminol- 

 ogy. (68) 



4. See tide station. 



158 



