BEAM TRANSMITTANCE METER 



2. A Labrador term for one-year ice formed 

 in bays or inlets. (59) 



3. In tiie antarctic, sometimes applied to 

 heavy floes recently broken away from an ice 

 shelf. (5) 



4. Young- flat sea ice sufficiently thick to im- 

 pede navigation. (59) Obsolete. 



baymouth bar — A bar e.xtending {jartially or en- 

 tirely across the moutli of a bay. (61) 



BAYMOUTH BAR 



bayou — A small sluggish stream or estuarial 

 creek, with a slow or imperceptible current, in 

 coastal swamps or river deltas. See slough. 

 (68) 



beach — (or seabeach). 1. The zone of uncon- 

 solidated material that extends landward from 

 the low water line to the place where there is 

 marked change in material or physiographic 

 form .... or to the line of permanent vegeta- 

 tion (usually the effective limit of storm waves) . 

 A beach includes foreshore and backshore. 



2. Sometimes, the material which is in more 

 or less active transport, alongshore or on-and- 

 off shore, rather than the zone. {See figure for 

 shore profile.) 



3. See strand, shoreline, coastline, tideland. 

 (61) 



beach berm — A nearly horizontal portion of the 

 beach or backshore formed by the deposit of 

 material by wave action. Some beaches have no 

 berms, others have one or several. (61) 



beachcomber — See comber. 



beach cusp — (also called cusp). One of a series 

 of low mounds of beach material separated by 

 crescent A-shaped troughs spaced at more or 

 less regular intervals along the beach face. 

 (61) 



beach erosion — The carrying away of beach ma- 

 terials by wave action, tidal currents, or lit- 

 toral currents, or by wind. (61) 



beach face — The section of the beach normally 

 exposed to the action of the wave uprush. The 



foreshore zone of a beach. (Not synonymous 

 with shoreface.) (See figures for suri zone 

 and shore profile.) (61) 



beach profile — See shore profile. 



beach ridge — An essentially continuous mound of 

 beach material behind the beach that has been 

 heaped up by wave or otJier action. Ilidges may 

 occur singly or as a series of apjiroximately 

 parallel deposits. In England they are called 

 fulls. (61) 



beachrock — (or beach sandstone). A friable to 

 well-cemented rock consisting of calcareous skel- 

 etal debris and, in many places, mineral grains 

 and rock fragments cemented by calcium car- 

 bonate. It is formed only in the intertidal 

 zone and occurs in thin beds dipping seaward 

 at angles of less than 15 degrees. See also cay 

 sandstone. (2) 



beach sandstone — See beachrock. 



beach scarp — An almost vertical slope along the 

 beach caused by erosion by wave action. It 

 may vary in height from a few inches to several 

 feet, depending on wave action and the nature 

 and composition of the beach. {See figure for 

 shore profile.) (61) 



beach width — The horizontal dimension of the 

 beach as measured normal to the shoreline. 

 (61) 



beam — A ray or collection of focused rays of ra- 

 diated energy. (5) 



(beam) attenuance meter — (or beam, transmit- 

 tance meter) . A radiance meter which meas- 

 ures the beam transmittance, 7', of a fixed path. 

 The beam attenuance C=l-T. (8) 



beam pattern — See directional response pat- 

 tern. 



beam sea — Waves moving in a direction approxi- 

 mately 90 degrees from the heading. Those 

 moving in a direction approximately opposite 

 to the heading are called head sea, those moving 

 in the general direction of the heading are called 

 following sea, and those moving in a direction 

 approxiately 45 degrees from the heading 

 (striking the quarter) are called quartering sea. 

 See cross sea. (68) 



beam tide — In navigational usage, a tidal current 

 setting in a direction approximately 90 degrees 

 from the heading of a ship. One setting in a 

 direction approximately 90 degrees from the 

 course is called a cross tide. In common usage 

 these two expressions are usually used synony- 

 mously. One setting in a direction approxi- 

 mately opposite to the heading is called a head 

 tide. One setting in such a direction as to in- 

 crease the speed of a ship is called a fair tide. 

 (68) 



beam transmittance — The transmittance for a 

 beam the diameter of which is small compared 

 to its length. (8) 



beam transmittance meter — See (beam) atten- 

 uance meter. 



19 



