NEUTRON 



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MASS TRANSPORT OF WAVES 

 I SURF J 1 1 



' zone' ' ' 



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lONG SHORE 

 CURRENT 



NEARSHORE CURRENT SYSTEM 



lAFTBI Wltoa, 19J31 



currents. Sometimes called inshore currents. 

 (73) 



Nearshore Environmental Analog Prediction 

 System — (formerly called Harbor Analog Sys- 

 tem). A technique used at the U.S. Naval 

 Oceanographic Office to classify nearshore areas 

 (shore to 30 fathoms) so that characteristics of 

 unsurveyed locations can be inferred from sur- 

 veyed locations in a similar class. 



nearshore water — See inshore water. 



nearshore zone — Pertaining to the zone extend- 

 ing seaward from the shore to an indefinite dis- 

 tance beyond the surf zone. 



near surface path — See surface path. 



neck — The narrow band of water flowing swiftly 

 seaward through the surf. See rip current. 

 (73) {See figure for nearshore current sys- 

 tem.) 



nectochaeta larva — A stage of the young of cer- 

 tain annelids, more advanced than the polytroc- 

 ular larva, in which muscle-powered para- 

 podia provide the swimming power. 



needle ice — See candle ice, frazil ice. 



negative gradient — A layer of water where tem- 

 perature decreases with depth. 



negative pressure duration — The length of time 

 the bottom pressure is affected by the passage 

 of the trough of a wave. It is approximately 

 equal to one-half the wave period. 



negative pressure response — The maximum 

 amount (in inches or feet of water) the bottom 

 pressure is reduced by the passage of the trough 

 of a wave. 



nekton — Those animals of the pelagic division 

 that are active swimmers, such as most of the 

 adult squids, fishes, and marine mammals. 



nematocyst — The stinging mechanism of coe- 

 lenterates, consisting of a chitinous sac filled 

 with venom and elongated at one end into a long 



narrow pointed hollow thread, whicli normally 

 lies inverted and coiled up within the sac but 

 can be everted by mechanical or chemical stimuli. 

 nepheloid zone — A suspension of fine organic 

 matter and clay-sized sediment particles in sea 

 water which forms a zone about 200 to 1,000 

 meters thick near the bottom of the continental 

 slope and rise in the western North Atlantic. 

 One theory holds that it results from the stirring 

 up of sea floor sediments by the turbulent flow of 

 bottom water. (16) 

 neritic — That portion of the pelagic division ex- 

 tending from low water level to the approximate 

 edge of a continental shelf. Some writers have 

 used this term in describing bottom organisms 

 of a continental shelf, but its recommended 

 usage is restricted to the waters overlying a 

 shelf. {See figure for classification of marine 

 environments.) 

 neritic province — See pelagic division, 

 neritic zone — See neritic. 

 ness — See headland, 

 net plankton — See microplankton. 

 net primary production — The total amount of 

 organic matter produced by photosynthetic 

 organisms, minus the amount consumed by 

 these organisms in their own respiratory proc- 

 esses. See primary production, 

 net radiometer — A device which measures the net 

 radiation by subtracting the outgoing long- wave 

 energy total from the incoming or reradiated 

 short-wave energy. 

 network — In surveying and gravity prospecting, 

 a pattern or configuration of stations, often ar- 

 ranged as to provide a check on the consistency 

 of the measured values, that is, a level network, 

 a gravity network based on the integration of 

 torsion balance gradients. 

 neuston — The group of organisms living in asso- 

 ciation with the surface film; the majority are 

 fresh water forms, since the ocean surface gen- 

 erally is too rough to support such a group. 

 The marine strider Haloiates and surface float- 

 ers, such as the Portuguese man-of-war, may be 

 considered to be neuston forms. 

 neutral estuary — An estuary in which neither 

 fresh water inflow nor evaporation dominates. 

 neutral filter — An optical filter which reduces 

 the magnitude of the radiant energy without 

 changing its relative spectral distribution. (8) 

 neutral shoreline — That shoreline whose essential 

 features do not depend on either submergence of 

 a former land surface or the emergence of a 

 former subaqueous surface. 

 neutron — An elementary nuclear particle with a 

 mass approximately the same as that of a hydro- 

 gen atom and electrically neutral; its mass is 

 1.008982 mass units. Neutrons are commonly 

 divided into sub-classifications according to their 

 energies as follows : thermal, around 0.025 elec- 

 tron-volts; epithermal, 0.1 to 100 electron-volts; 

 slow, less than 100 electron-volts ; intermediate. 



109 



