ANTERIOR . The forward -moving or head end of an 

 animal, or toward that end. Opposite of posterior. 

 (19) 



ANTINODE . See LOOP, 



ANTINODE (LOOP) . An antinode is a point, line or 

 surface in a standing wave where some character- 

 istic of the wave has a maximum value. (9) 



ANTIRESONANCE . For a system in forced oscillation, 

 antiresonance exists at a point when any change, 

 however small, in the frequency of excitation 

 causes an increase in the response at this point. 

 (1) 



ANTITRADES . A deep layer of westerly winds in the 

 troposphere above the surface TRADE-WINDS of the 

 tropics). They comprise the equatorward side of the 

 mid-lat|itude WESTERLIES, but are found at upper 

 levels rather than at the surface. 



The antitrades are best developed in the win- 

 ter hemisphere, and also above the eastern extremi- 

 ties of the subtropical highs. Further west their 

 base is higher and their appearance less regular. 



The antitrades were formerly regarded as 

 return currents carrying away, to higher latitudes, 

 the air which rises in the INTERTROPICAL CONVER- 

 GENCE ZONES, the westerly component being due to 

 the conservation of angular momentum as the air 

 moves into higher latitudes. Bjerknes, J. ("La 

 Circulation Atmospherique dans les Latitudes Sous- 

 Tropicales," Scientia, 57:1935, pp. 114-123) 

 showed that this explanation is incomplete: the 

 antitrades are dynamical in origin and constitute 

 an essential part of the atmosphere's primary cir- 

 culation. (24) 



ANTLANTNIRO . Atlantic Scientific Research Institute 

 of Fishing Economy and Oceanography (USSR) . 



ANZAAS. Australian and New Zealand Association for 

 the Advancement of Science. 



AO . U. S. Navy ship designation for an Oiler. 



APE . U. S. Navy designation for a Fast Combat 

 Support Ship. 



AOG . U. S. Navy ship designation for a Gasoline 

 Tanker . 



when the moon is near apogee. The range at this 

 time is called apogean range and usually does not 

 occur until 1 to 3 days after the moon reaches 

 apogee. This lag is called age of parallax in- 

 equality, or parallax age. (17) 



The apogean range (An) 

 of tide is the average semidiurnal range occurring 

 at the time of apogean tides and is most convenient- 

 ly computed from the harmonic constants. It is 

 smaller than the mean range where the type of tide 

 is either semidiurnal or mixed, and is of no prac- 

 tical significance where the type of tide is 

 diurnal. (14) 



APPARENT COHESION . In soil mechanics, the resis- 

 tance of particles to being pulled apart due to 

 the surface tension of .the moisture film surround- 

 ing each particle. Also called MOISTURE FILM 

 COHESION. (27) 



APPARENT SOURCE . See EFFECTIVE CENTER. 



APPARENT TIME . Time based upon the true position 

 of the sun as distinguished from mean time, which 

 is measured by a fictitious sun moving at a uniform 

 rate. Apparent time is that shown by the sun- 

 dial, and its noon is the time when the sun crosses 

 the meridian. The difference between apparent time 

 and mean time is known as the equation of time. 

 Although quite common many years ago, apparent time 

 is now seldom used. (14) 



AP(SS) . U. S. Navy designation for a Transport 

 Submarine . 



AR . U. S. Navy designation for a Repair Ship. 



ARE . U. S. Navy designation for a Battle Damage 

 Repair Ship. 



ARC . U. S. Navy designation for a Cable Repairing 

 or Laying Ship. 



ARCHED ICEBERG . An ICEBERG eroded in such a manner 

 that a large opening at the water line extends 

 horizontally through the iceberg forming an arch. 

 (25) 



ARCHED SQUALL . See SQUALL. 



ARCHIBENTHIC ZONE. See BENTHIC DIVISION. 



AOG . Atlantic Oceanographic Group. 



AOR. U. S. Navy designation for a Replenishment 

 Fleet Tanker. 



AO(SS) . U. S. Navy designation for Submarine Oiler. 



AP . U. S. Navy designation for a Transport. 



APA. U. S. Navy designation for an Attack Trans- 

 port Ship. 



APE . U. S. Navy designation for a Self-Propelled 

 Barradks Ship. 



APC. U. S. Navy designation for a Small Coastal 

 Transport. 



APD . U. S. Navy designation for a High Speed 

 Transport Ship. 



APHOTIC ZONE . See EUPHOTIC ZONE. 



AFO . Association of Physical Oceanographers . 



APOGEAN TIDAL CURRENTS . Tidal currents of decreased 

 speed occurring at the time of apogean tides. (17) 



APOGEAN TIDES . Tides of decreased range occurring 



ARCHIMEDES . A manned submersible vehicle (French). 



ARCHIMEDES PRINCIPLE . States that any object 

 wholly or partially immersed in a liquid is buoyed 

 by a force equal to the weight of the liquid it 

 displaces. (37) 



ARCHIPELAGIC APRON . A fan-shaped slope around an 

 oceanic island differing from deep-sea fans in 

 having little, if any, sediment cover. (27) 



ARCHIPELAGO . A group of islands; a sea studded 

 with many islands. (27) 



ARCS . Ridges which are curved, and particularly if 

 parts of them rise above sea level. (oceans) (see 

 ridge) 



ARCTIC CIRCLE . The line of latitude 66°32'N (often 

 taken as 66 1/2 N) . Along this line the sun does 

 not set on the day of the summer solstice, about 

 June 21, and does not rise on the day of the winter 

 solstice, about December 22. From this line the 

 number of twenty-four hour periods of continuous 

 day or of continuous night increases northwards 

 to about six months each at the North Pole. (24) 



ARCTIC CURRENT. See LABORADOR CURRENT. 



