COMPOUND TIDE 



coefficient of thermal expansion — (or coefiloient 

 of expansion). The relative increase of the 

 vohime of a system (or substance) with increas- 

 ing tenii^eratiire in an isobaric process. In 

 symbols this coefficient is 



■where V is the volume, T the temperature, and p 

 the pressure. (5) 



coelenterate — One of a phylum (Coelenterata or 

 Cnidaria) of two-staged (sessile and free-float- 

 ing) organisms. The sessile stage basically is 

 cylindrical and is called a polyp; the free- 

 swimming stage is disc or bell shaped and is 

 called a medusa or jellyfish. Many coelenter- 

 ates, particularly the hydrozoans and corals, 

 are colonial, consisting of many polyps united 

 in complex or massive stnictures. All contain 

 stinging cells or nematocysts, many exhibit 

 bioluminescence, and some reportedly scatter 

 sound. See hydrozoan, scyphozoan, antho- 

 zoan. 



col — In meteorology, tlie point of intersection of a 

 trough and a ridge in the pressure pattern of a 

 weather map. It is the point of relatively low- 

 est pressure between two highs and the point of 

 relatively highest pressure between two lows. 

 (5) 



cold light — Light emitted by any body whose tem- 

 perature is below that of incandescence. 



cold pool — ^A body of cold water entirely sur- 

 rounded by warm water. 



cold wall — The steep water-temperature gradient 

 between the Gulf Stream and (a) the slope 

 water inshore of tlie Gulf Stream or (b) the 

 Labrador Current. It is considered part of the 

 Arctic Convergence by most oceanographers. 

 (5) 



collar ice — See ice foot. 



collector — In underwater optics a device required 

 to fulfill the definition of the quantity being 

 measured, for instance, a Gershun tube in radi- 

 ance measurements or a cosine collector in 

 irradiance measurements. (8) 



colligative property — One of four characteristic 

 properties of solutions, namely the interdepend- 

 ent changes in vapor pressure, freezing point, 

 boiling point, and osmotic pressure, with a 

 change in amount of dissolved matter. If, under 

 a given set of conditions, the value for any one 

 property is known, the others may be computed. 

 In general, with an increase in dissolved matter 

 (for example, salt in sea water) freezing point 

 and vapor pressure decrease, and boiling point 

 and osmotic pressure increase. (5) 



colloid — As a size term refers to particles smaller 

 than 0.00024 millimeter, smaller than clay size. 



colonial coral — Coral in which the individuals 

 are attached together as units, and do not exist as 

 separate animals. (2) 



colored filter— ^S'ee selective filter. 



comber — {nho cM^il roUer, heachcomher) . 1. A 

 deejiwatei- wave whose crest is pushed forward 

 by a strong wind and which is much larger than 

 awhitecap. (61) 



2. A long-period spilling breaker. If there 

 are many lines of breakers simultaneously on a 

 shore, they form a surf. 



comb jelly — See ctenophore. 



commensalism— A symbiotic relationship be- 

 tween two species in which one species is bene- 

 fitted and the other is not harmed. The rela- 

 tionship between the shark and the remora or 

 "suckerfish" is an example of commensalism. 

 See mutualism, inquilinism, symbiosis. 



common establishment— /S^ee establishment of 

 the port. 



community — (also called iiocenose, blocenosis). 

 An integrated, mutually adjusted assemblage of 

 plants and animals inhabiting a natural area. 

 The assemblage may or may not be self-sufficient 

 and is considered to be in a state of dynamic 

 equilibrium. Although the community concept 

 is clear, specific communities and their limits, 

 particularly in the ocean, are often difficult to 

 recognize. The community usually is character- 

 ized as having a more or less definite species 

 composition and may be defined on the basis of 

 the habitat it occupies or on the basis of the 

 siDecies present. 



compact ice — See conglomerated ice, 



compaction — The decrease in volume or thickness 

 of a sediment under load through closer crowd- 

 ing of constituent particles and accompanied by 

 decrease in porosity, increase in density, and 

 squeezing out of interstitial water. (2) 



compensation depth — The depth at which photo- 

 synthesis equals jilant respiration during a 

 24:-hour period. 



compensation point — See compensation depth. 



component — See constituent. 



composite chart — A chart based on data for ex- 

 tended periods, usually 5 to 10 days, treated as 

 being synoptic. 



composite sample — See compound sample. 



compound pancake ice — Ice pancakes which have 

 frozen together. (68) 



compound ripples — See ripple marks. 



compound sample — (or aggregate sample^ com- 

 'posite sample) . A mixture of a number of spot 

 samples to form an aggregate single sample. 



compound shoreline — That shoreline whose 

 essential features combine elements of at least 

 two of the other shoi-eline classifications, that is, 

 emergence, submergence, or neutral shoreline. 



compound specific activity — Total radioactivity 

 of a given isotope per gram of a compound. 

 (70) 



compound tide — A tide constituent with a speed 

 equal to the sum or difference of the speeds of 

 two or more basic constituents. Compound tides 



35 



