east coast of Brazil, from a point west of Ascen- 

 sion Island nearly to the Rio de la Plata, widening 

 and curving southeastward, and continuing as part 

 of the SOUTH ATLANTIC CURRENT. The Brazil current 

 is the southern branch of the SOUTH EQUATORIAL CUR- 

 RENT, which divides between Ascension Island and 

 Brazil, and it forms the western part of the gen- 

 eral counterclockwise oceanic circulation of the 

 South Atlantic Ocean. (17) 



BREAKER . A sea-surface wave which has become too 

 steep to be stable. Waves in shoaling water become 

 higher and shorter (hence steeper) as the water 

 becomes shallower. When the steepness (ratio of 

 wave height to wave length) exceeds 1/7, the laws 

 which govern surface-wave motion can no longer be 

 satisfied and the crest of the wave outraces the 

 body of the wave to form a foaming white turbulent 

 mass of water called a breaker. 



Roughly, three kinds of breakers can be dis- 

 tinguished, depending primarily on the gradient of 

 the bottom: (a) Spilling breakers (over nearly flat 

 bottom) which form a foamy patch at the crest and 

 break gradually over a considerable distance; (b) 

 Plunging breakers (over fairly steep bottom gradient) 

 which peak up, curl over with a tremendous overhang- 

 ing mass, and then break with a crash; (c) Surging 

 breakers (over very steep bottom gradients) which 

 do not spill or plunge but surge up the beach face. 



Waves also break in deep water if they build 

 too high while being generated by the wind, but 

 these are usually short-crested and are termed 

 Whitecaps. (24) 



BREAKER DEPTH (BREAKING DEPTH) . The still water 

 depth at the point where the wave breaks . (10) 



BREAKING DEPTH . See BREAKER DEPTH. 



BREAKUP. EARLIEST . Earliest reported date that 

 landfast and pack ice begin to disintegrate prior 

 to final clearance. 



BREAKUP. LATEST . Latest reported date that land- 

 fast and pack ice begin to disintegrate prior to 

 final clearance. 



BREAKWATER . A structure protecting a shore area, 

 harbor, anchorage or BASIN from waves. (11) 



BREATHHOLDING . Diving without breathing apparatus 

 requires breath holding during submergence, and 

 methods of prolonging the length of time the breath 

 can be held are always of interest to skindivers 

 and the like. The discomfort which forces a man 

 to resume breathing arises largely from the two 

 main mechanisms concerned with the control of 

 breathing. Rising carbon dioxide tension stimulates 

 the respiratory center directly while falling oxy- 

 gen tension stimulates it via the cherao-receptors . 

 As the degree of stimulation increases, it becomes 

 more and more difficult to restrain the urge to 

 breathe; and at some point, the individual will 

 "break" and resume breathing. (37) 



BRINE . Sea water containing a higher concentration 

 of dissolved salt than that of the ordinary ocean. 



Brine is produced by the evaporation or freez- 

 ing of sea water, for, in the latter case, the SEA 

 ICE formed is much less saline than the initial 

 liquid, leaving the adjacent unfrozen water with 

 increased SALINITY. The liquid remaining after 

 sea water has been concentrated by evaporation un- 

 til salt has crystallized is called BITTERN. (24) 



BRITTLE MATERIAL . A nonductile material which 

 fails catastrophically under dynamic loading con- 

 ditions. CERAMICS are an example of a class of 

 brittle materials. 



BROAD ON THE BOW . Bearing 045° relative (broad on 

 the starboard bow) or 315° relative (broad on the 



port bow). If the bearings are approximate, the 

 expression on the bow should be used. (17) 



BROAD ON THE QUARTER . Bearing 135° relative (broad 

 on the starboard quarter) or 225° relative (broad 

 on the port quarter) . If the bearings are approxi- 

 mate, the expression on the quarter should be used, 

 (17) 



BROKEN BELT . The transition zone between open 

 water and consolidated ice. (17) 



BROKEN ICE . Ice that covers from five-tenths to 

 eight-tenths of the sea surface. Also called 

 loose ice, loose pack ice, open ice, open pack 

 ice, slack ice. (17) 



BROKEN HATER . Water having a surface covered with 

 ripples or eddies, and usually surrounded by calm 

 water. (17) 



BROWN CLAY . See RED CLAY. 



BRUMA . A haze that appears in the afternoons on 

 the coast of Chile when sea air is transported 

 inland. (17) 



BRYOZOANS . Minute animals, usually forming plant- 

 like colonies, which attach from the tidal zone to 

 great depths. (15) 



B-SCOPE . A Cathode Ray Oscilloscope (CRO) indica- 

 tor having a rectangular plot of range vs bearing. 

 Spot brightness indicates echo intensity. (5) 



BSF&W . Bureau of Sport Fisheries and Wildlife: 



The BSF&W (U.S. Department of Interior) re- 

 search program consists of the following two objec- 

 tives: 1. Life history studies of fish species, 

 to fill gaps in knowledge about distribution in 

 space and time, age, rates of growth, identity, 

 sizes of populations, migratory habits, food habits, 

 reproductive seasons, enemies, parasites, and 

 diseases; and 2. Analysis of environments, to 

 identify and measure factors affecting distribution, 

 movements, abundance, and well-being of game-fish 

 species . 



Laboratory and field research are at the 

 Bureau's Atlantic Laboratory on Sandy Hook, New 

 Jersey, and its Pacific Laboratory at Tiburon, 

 California. 



BT. Bathythermograph. 



BUCKET TEMPERATURE . The surface temperature of the 

 sea as measured by a BUCKET THERMOMETER or by im- 

 mersing a SURFACE THERMOMETER in a freshly-drawn 

 bucket of water. (24) 



BUCKET THERMOMETER . A water-temperature thermome- 

 ter provided with an insulated container around 

 the bulb. It is lowered into the sea on a line 

 until it has had time to reach the temperature of 

 the surface water, then withdrawn and read. The 

 insulated water surrounding the bulb preserves the 

 temperature reading and is available as a SALINITY 

 sample, (24) 



BUDDY BREATHING . In SCUBA, the sharing by two or 

 more divers of the same breathing tank. See BUDDY 

 SYSTEM. 



BUDDY SYSTEM . In SCUBA diving, divers with few 

 exceptions should work in pairs . This is probably 

 the greatest single aid toward SCUBA safety, es- 

 pecially under unfavorable conditions. The divers 

 should remain in sight of each other. In poor 

 visibility, they should use a "buddy line" 6-10 

 feet long. (37) 



BUDOCKS , Bureau of Yards and Docks (USN) . 



17 



