MILKY SEA 



and performance of ships, equipment, or weap- 

 ons. (39) 



milky sea — See sheet-type luminescence. 



milky weather — See whiteout. 



Millepore * filter — A copyrighted trade name for 

 a membrane filter. 



millicurie — (abbreviated mc). One-thousandth 

 of a curie. (41) 



milligauss — A unit of magnetic force equal to 

 0.001 gauss (oersted) or 100 gammas. 



million-electron-volt — (abbreviated Mev). A 

 common unit of energy in nuclear science, equiv- 

 alent to 10"* electron-volts. (41) 



milliroentgen — One-thousandth of a roentgen. 



minimum — The least value attained (or attain- 

 able) by a function ; the opposite of maximum. 



(5) 



minimum current— The phase of the tidal cur- 

 rent when the speed is least ; usually referenced 

 in knots and in hours before or after low and 

 high water. {See figure for current ellipse.) 



minimum duration — ^The time necessary for 

 steady state wave conditions to develop for a 

 given wind velocity over a given fetch length. 



minimum ebb — The lowest speed of a continuously 

 outflowing current during the period of ebb tidal 

 current, usually in a river or estuary; where 

 currents are solely tidal, the lowest speed of an 

 ebb current is at or near slack water. See 

 river discharge. 



minimum flood — Where currents are solely tidal, 

 the lowest speed of a flood current is at or near 

 slack water. 



minor constituents — Those chemical elements 

 present in sea water which together comprise 

 approximately 0.1 percent of the total known 

 dissolved solid constituents. Nearly all of the 

 elements occur in sea water, although most are 

 present in extremely small amounts. See con- 

 stituents of sea water. 



mixed current — The type of tidal current char- 

 acterized by a conspicuous difference in speed 

 and duration between the two successive flood 

 or two successive ebb currents occurring during 

 any tidal day. (50) 



mixed layer — The layer of the water which is 

 mixed through wave action or thermohaline 

 convection. 



mixed layer depth — The depth of the bottom of 

 the mixed layer. 



mixed tide — ^The type of tide in which a diurnal 

 wave produces large inequalities in heights and/ 

 or durations of successive high and/or low 

 waters. This term applies to the tides inter- 

 mediate to those predommantly semidiurnal and 

 those predorninantly diurnal. {See figure for 

 types of tide) . 



mixotrophic nutrition — The process by which an 

 organism obtains its food by both autotrophic 



and heterotrophic modes. See autotrophic nu- 

 trition, heterotrophic nutrition. 



mixture — Mixtures consist of two or more sub- 

 stances intermingled with no constant percent- 

 age composition, and with each component re- 

 taining its essential original properties. (27) 



moat — An annular depression that may not be 

 continuous, located at the base of many sea- 

 mounts or islands. (62) 



mode — The item, in a series of statistical data, 

 which occurs most often. 



modified Mercalli scale — See earthquake inten- 

 sity. 



Mohole — A proposed deep borehole to penetrate 

 the earth's crust and into the earth's mantle 

 below the Mohorovicic discontinuity. (2) 



Mohorovicic discontinuity — (abbreviated Mo- 

 ho). The sharp discontinuity in composition 

 between the outer layer of the earth (the crust) 

 and the next inner layer (the mantle). This 

 was discovered by Mohorovicic from seismo- 

 grams. The thiclmess of the crust has been de- 

 termined by the refraction of seismic waves at 

 this discontinuity which is situated about 35 

 kilometers below the continents and about 10 

 kilometers below the ocean basins and defines 

 the top of the mantle. {See figure for earth 

 structure.) 



Mohr-Knudsen method — A chemical method 

 for estimating the chlorinity of sea water. In 

 this method, the volume of silver nitrate neces- 

 sary to precipitate the sample in relation to the 

 volume of silver nitrate necessary to precipitate 

 normal water is determined by titration using 

 potassium chromate as an indicator. 



The chlorinity is calculated by Knudsen's 

 Tables. 



moisture flux — See eddy flux. 



mold — See fungus. 



mole — 1. See gram-molecular weight. 



2. A massive structure of masonry or large 

 stones serving as a pier or breakwater, or both. 

 (68) 



molecule — The smallest unit quantity of matter 

 which can exist by itself and retain all the prop- 

 erties of the original substance. (27) 



mollusk — (also spelled mollusc). One of a phy- 

 lum (Mollusca) of soft unsegmented animals, 

 most of which are protected by a calcareous 

 shell. The phylum is second only to the insects 

 in number of species. Some members are an 

 important food source, some are dangerous to 

 man, some are notable fouling organisms, and 

 others are destructive to wood, concrete, and oth- 

 er submerged materials. The group includes 

 the snails, bivalves, chitons, squid, and octo- 

 pus. 



momentum — That property of a particle which 

 is given by the product of its mass with its 

 velocity. 



momentum flux — See eddy flux. 



106 



