ENVIRONMENTAL FACTORS 



electrostatic transducer— A transducer that 

 consists of a capacitor and depends upon inter- 

 action between its electric field and the change 

 of its electrostatic capacitance. (69) 



element — 1. One of the simpler parts of which a 

 complex entity is composed; thus a part of an 

 instrument, as the thermal element of a 

 bathythermograph or a constituent of the at- 

 mospliere, such as nitrogen, oxygen, water 

 vapor, carbon dioxide, etc. 



2. In chemistry, a substance which cannot 

 be broken down by ordinary chemical means 

 into simpler components (although one element 

 may be transformed into another by some form 

 of subatomic bombardment) . 



(5) 



elevated island — An island that rises to a few 

 feet above high tide level on a reef flat and 

 consists either of sand and debris or of solid 

 reef rock. (2) 



elevation — A general term for a relief feature of 

 any size which rises above the surrounding 

 sea bed. 



elk kelp — One of a genus {Pelagophyciis) of large 

 brown algae, which consists of a massive hold- 

 fast and a long tough stipe terminated by a 

 large bulbous pneumatocyst from which a 

 single forked lamina-bearing branch radiates. 

 The genus occurs only on the Pacific coast of 

 North America from Point Conception, Cali- 

 fornia southward along the coast of California 

 and Baja California and reaches lengths of 100 

 feet or more. 



Elmo's fire — See St. Elmo's fire. 



El Nino — A warm current setting south along the 

 coast of Ecuador. It generally develops just 

 after Christmas concurrently with a southerly 

 shift in the tropical rain belt. In exceptional 

 years the current may extend along the coast of 

 Peru to 12°S. When this occurs, plankton and 

 fish are killed in the coastal waters and phenom- 

 enon somewhat like the red tide of Florida re- 

 sults. During this time discolored water and 

 intense displays of bioluminescence are com- 

 mon. El Nino is much more widespread and 

 destructive than the more local phenomenon of 

 agua je, which occurs every year. ( 5 ) 



El Pintor — See Callao Painter. 



embacle — A term, now rarely used, for the heap- 

 ing up of ice in a stream following a freeze. 

 (59) 



embayment — An indentation in a shoreline form- 

 ing an open bay. 



embouchure — See mouth. 



emergence — The fact that part of the ocean floor 

 has become dry land but does not imply whether 

 recession of the sea or elevation of the land was 

 the specific cause. (2) 



emissivity — (sometimes called emissive poioer). 

 The ratio of the emittance of a given surface at 

 a specified wavelength and emitting tempera- 



ture to the emittance of an ideal black body 

 at the same wavelength and temperature. The 

 greatest value that an emissivity may have is 

 unity, the least value zero. 



It is corollary of Kirchofif's law that the 

 emissivity of any surface at a specified tem- 

 perature and wavelength is exactly equal to the 

 absorptivity of that surface at the same tem- 

 perature and wavelength. ( 5 ) 



encrusting bryozoan — (or coral patch). A 

 bryozoan which forms hard crusts on under- 

 water surfaces. 



endoergic reaction — A reaction which absorbs 

 energy. (70) 



endothermic reaction — A reaction which absorbs 

 energy specifically in the form of heat. (70) 



energetics — The branch of study dealing with the 

 systematic description of the energy conversion 

 and transfer processes which take place within 

 a physical system. (5) 



energy coefficient — The ratio of the energy in a 

 wave per unit crest length transmitted forward 

 with the wave at a point in shallow water to the 

 energy in a wave per unit crest length trans- 

 mitted forward with the wave in deep water. 

 On refraction diagrams this is equal to the 

 ratio of the distance between a pair of orthogo- 

 nals at a selected point to the distance between 

 the same pair of orthogonals in deep water. 

 Also the square of the refraction coefficient. 

 (61) 



English system — A system of physical units 

 based on the use of the foot, pound, and second 

 as elementary quantities of length, mass, and 

 time, respectively. This system, although being 

 displaced by the cgs system, is still in use in 

 many English-speaking countries. 



ensemble average — An average determined over 

 a finite subset of random time functions for some 

 particular instant of time. 



ensonif y — The penetration of sound into any par- 

 ticular part of the sea. 



entrainment — 1. The transfer of fluid by friction 

 from one water mass to another, usually occur- 

 ring between opposing currents. The turbu- 

 lence between the water masses results in mixing. 

 2. The pick-up and movement of sediment as 

 bed load or in suspension by current flow. 



entropy — 1. A measure of the unavailable energy 

 in a system, that is, energy that cannot be con- 

 verted into another form of energy. 



2. A measure of the degree of mixing of dif- 

 ferent kinds or sizes of sediments ; high entropy 

 approaches an unmixed sediment of one kind. 

 (2) 



environment — The sum total of all the external 

 conditions which may affect an organism, com- 

 munity, material, or energy, if brought under 

 the influence of these external conditions. (2) 



environmental factors — In oceanography, the 

 physical and chemical conditions such as tem- 



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