tion of fog. In the coastal valleys, fog is formed 

 when moist air blown inland during the afternoon is 

 cooled by radiation during the night. (17) 



CALLIPPIC CYCLE . A period of four METONIC CYCLES 

 equal to 76 Julian years, or 27759 days. Devised 

 by Callippus, a Greek astronomer, about 350 B.C. 

 as a suggested improvement on the Metonic cycle for 

 a period in which new and full moon would recur on 

 the same day of the year. Taking the length of the 

 synodical month as 29.530588 days, there are 940 

 lunations in the Callippic cycle, with about 0.25 

 day remaining. (14) 



CALM . 1. The absence of apparent motion of the 

 air. In the BEAUFORT WIND SCALE, this condition is 

 reported when smoke is observed to rise vertically, 

 or the surface of the sea is smooth and mirror- 

 like. In the United States weather observing prac- 

 tice, the wind is reported as calm if it is deter- 

 mined to have a speed of less than one mile per 

 hour (or one knot) . (24) 



CALM BELT . A belt of latitude in which the winds 

 are generally light and variable. The principal 

 calm belts are the HORSE LATITUDES (the CALMS OF 

 CANCER and of CAPRICORN) and the DOLDRUMS. (24) 



CALMS OF CANCER . Along with the "calms of Capri- 

 corn", the light variable winds and calms which 

 occur in the centers of the SUBTROPICAL HIGH-PRES- 

 SURE BELTS over the oceans. 



They are named after the Tropics of Cancer and 

 Capricorn, although their usual position is at about 

 latitudes 30°N and S, the HORSE LATITUDES. (24) 



CALMS OF CAPRICORN . See CALMS OF CANCER. 



CALVED ICE . A fragment of floating GLACIER ICE 

 ranging in size from an ICEBERG to a GROWLER. (25) 



CALVING. The breaking away of a mass of ice from 

 its parent ICEBERG, GLACIER, or SHELF ICE forma- 

 tion. 



Calving may take place above, at, or below the 

 water line, relieving stresses set up by tempera- 

 ture changes and responding to vibrations from 

 sound or wave action. ICEBERGS at any time may 

 calve off large sections of ice which, after fall- 

 ing into the water, may bob up to the surface with 

 great force, often at a considerable distance away. 

 In the calving of the largest valley glaciers of 

 Greenland, masses of ice of the order of 1/40 to 

 1/20 cubic mile are spalled off--one of the most 

 gigantic natural spectacles on earth. The waves 

 which are produced in the fjords rise several tens 

 of yards along the banks and therefore compare 

 favorably with the largest waves of the sea. 



Icebergs are often so balanced that this calv- 

 ing, or merely melting of the under surface, will 

 cause a shift in the center of gravity with conse- 

 quent capsizing and readjustment of mass to a new 

 state of equilibrium. (25) 



CANAL. An artificial watercourse cut through a 

 land area for use in navigation, irrigation, etc. 

 (11) 



CANDLE ICE . Ice fingers normal to the original 

 free surface in rotten or disintegrating SEA ICE. 

 The fingers may be equal in length to the thickness 

 of the ICE CAKE prior to disintegration. CANDLE 

 ICE is also a feature of disintegrating lake and 

 river ice. (25) 



CANISTERS . The absorption canister is a component 

 of CLOSED-CIRCUIT SCUBA. It is a container for 

 the chemical absorbent that removes carbon dioxide 

 from exhalation. It may take a variety of shapes. 

 Most often it is cylindrical. The design must 

 provide for adequate filling so that the absorbent 

 does not settle in use leaving a bypass channel 

 along the canister wall. 



Most canisters are made of nonferrous metal 

 with a protective coating for corrosion resistance. 

 Canisters are rugged enough to withstand normal 

 handling. They usually have watertight filling 

 caps for easy filling or changing of the absorbent. 

 They may have baffles to insure against channeling 

 and to increase the path of gases through the 

 absorbent without increasing breathing resistance 

 excessively. (37) 



CANYON (SUBMARINE CANYON) . A relatively narrow, 

 deep depression with steep slopes, the bottom of 

 which grades continuously downward. (25) 



CAPACITANCE . The ability to store electrical 

 energy, measured in farads, microfarads, or micro- 

 microfarads . (36) 



CAPACITOR . Two electrodes, or sets of electrodes, 

 in the form of plates, separated from each other 

 by an insulating material called the dielectric. 

 (36) 



CAPACITOR HYDROPHONE . See ELECTROSTATIC TRANSDUCER. 



CAPE . An area of land projecting into a body of 

 water, either as a peninsula or as an angle of the 

 coast line. A cape is similar to but generally ^. 

 more prominent than a point. (17) 



CAPE DOCTOR . The strong southeast wind which blows 

 on the South African coast. (17) 



CAPE HORN CURRENT . That part of the west wind 

 drift current flowing eastward in the immediate 

 vicinity of Cape Horn, and then curving northeast- 

 ward to continue as the FALKLAND CURRENT. (17) 



CAPILLARY WAVE . (Also called RIPPLE, CAPILLARY 

 RIPPLE.) A wave, on a fluid interface, of suffi- 

 ciently short WAVE LENGTH that the restoring force 

 is surface tension. 



The PHASE SPEED C of these waves on a free 

 surface decreases with increasing wave length: 



C = \/2ii T/p L 

 where T is the surface tension of the fluid, P 

 the density, and L the wave length. For a water- 

 air surface, the wave length of a wave moving 

 Im/sec is about 0.04 cm. (24) 



CANARY CURRENT . A North Atlantic Ocean current 

 flowing southwestward along the northwest coast of 

 Africa, from the Canary Islands to the vicinity of 

 the Cape Verde Islands, where it divides into two 

 branches, the western branch augmenting the NORTH 

 EQUATORIAL CURRENT and the eastern branch curving 

 southeast and continuing as the GUINEA CURRENT. 

 The Canary current forms the southeastern part of 

 the general clockwise oceanic circulation of the 

 North Atlantic Ocean. (17) 



CAN BUOY . A buoy the above-water part of which is 

 in the shape of a cylinder. Sometimes called 

 cylindrical buoy. (17) 



CAPTURE AREA . The effective, or apparent, area of 

 the receiving surface of a hydrophone may be com- 

 puted as the quotient of the available power of 

 the acoustic energy divided by its equivalent plane 

 wave intensity. The value of the area determined 

 in this manner, for a given hydrophone, is known 

 as its capture area. (4) 



CARBON DIOXIDE . A heavy, colorless gas of chemical 

 formula CO2. It is the fourth most abundant con- 

 stituent of dry air, now present to the extent of 

 0.033 per cent by volume. 



Over 99 per cent of the terrestrial CO2 is 

 found in the oceans, but its solubility is strongly 

 temperature-dependent, so changes in sea surface 



20 



