uatlon of downward-directed radiation in the sea. 



I \ 



The coefficient K is defined by K = 2.303 log 



I \., 



where I^j is the intensity of radiation of a given 

 wavelength X on a horizontal surface and IX,-, is the 

 intensity on a horizontal surface 1 meter deeper. 

 K varies with wavelength, with the nature of the 



scattering particles, and with the presence of 

 dissolved colored substances. (24) 



EYE OF THE STORM . The center of a tropical cyclone, 

 marked by relatively light winds, confused seas, 

 rising temperature, lowered relative humidity, and 

 often by clear skies. The general area of lowest 

 atmospheric pressure of a cyclone is called storm 

 center. (17) 



F 



FACE PLATE . A glass or plastic window worn over 

 the SCUBA or SKIN DIVERS face and designed to pro- 

 vide an air space between the diver's eyes and the 

 water. The face plate permits both eyes to see in 

 the same plane. A full face plate covers the eyes, 

 mouth and nose while a regular face plate covers 

 the eyes and nose only. 



FACIES . See BIOTOPE, 



FACSIMILE CHART (FAX CHART. FAX MAP) . In meteorol- 

 ogy, any graphic form of weather information, 

 usually a type of synoptic chart, which has been 

 reproduced by facsimile equipment. Master charts 

 are plotted and analyzed at central weather stations, 

 and these maps are transmitted by facsimile equip- 

 ment via radio or wire to individual weather sta- 

 tions. (24) 



FAC/SPC . Fisheries Advisory Committee of the South 

 Pacific Commission. 



FACULTATIVE BACTERIA . Bacteria which utilize free 

 oxygen in respiration, but can also live in the 

 total absence of free oxygen. (13) 



FAGS. Federation of Astronomical and Geophysical 

 Science. 



FAIR TIDE . A tidal current setting In such a 

 direction as to increase the speed of a vessel. 

 One setting in a direction approximately opposite 

 to the heading is called a head tide. One abeam 



Is called a beam tide, 

 the course Is called c 



One approximately 90 

 cross tide. (17) 



from 



FAIRWAY . The main traveled part of a waterway; 

 a marine thoroughfare. (17) 



FAIRWAY BUOY . A buoy marking a fairway, with safe 

 water on both sides. (17) 



FAIR WIND . A wind which aids a craft in making 

 progress in a desired direction. Used chiefly in 

 connection with sailing vessels, when it refers to 

 a wind which permits the vessel to proceed in the 

 desired direction without excessive changing of 

 course. When applied to a power vessel or an air- 

 craft, it refers to a wind which increases the 

 speed of the craft. A wind which delays the pro- 

 gress of a craft is called an unfavorable ^wlnd . 

 Also called favorable wind. (17) 



FALKLAND CURRENT . A South Atlantic Ocean current 

 flowing northeastward along the east coast of South 

 America from Cape Horn to the Rio de la Plata, 

 widening and curving eastward to continue as part 

 of the SOUTH ATLANTIC CURRENT. The Falkland cur- 

 rent is a continuation of the CAPE HORN CURRENT. 

 (17) 



FALLING TIDE. See EBB TIDE. 



FALSE CIRRUS . Cirrus proceeding from cumulonimbus, 

 and composed of the debris of the upper frozen 

 parts of the cloud. (17) 



FALSE ICE FOOT . Ice formed along a beach terrace 

 and attached thereto just above the high water mark. 

 It is derived from water originating from melting 

 snow above the beach terrace. This formation is 

 termed a false ice foot because, unlike a true ICE 

 FOOT, it has its base above the low water mark. A 

 false ice foot may be added to by accretions of 

 SEA ICE resulting from waves, spray, and spring 

 tides. (25) 



FAN . A gently sloping, cone-shaped accumulation of 

 material normally located at the mouth of a CANYON, 

 (26) 



FAO. Food and Agriculture Organization of the UN 

 (United Nations). 



FAREWELL BUOY . See SEA BUOY. 



FASEB . Federation of American Societies for Ex- 

 perimental Biology. 



FAST ICE (COASTAL ICE. COAST ICE. LANPFAST ICE) . 

 ice which is held in position by contact with or 

 attachment to the shore or bottom. It is called 

 ICE FOOT if frozen to the shore, shore ice if cast 

 onto the shore or beached, stranded ice if grounded, 

 and BOTTOM ICE if frozen to the bottom. Ice which 

 is not in contact with or attached to the shore or 

 bottom is called floating ice. (17) 



FAST RESPONSE CUP ANEMOMETER . This instrument is a 

 standard device for the measurement of wind speed. 

 The fast response Anemometer is used for accurate 

 dynamic measurements in turbulent wind regimes. 

 These wind measurements are important to oceano- 

 graphy due to the fact that winds generate waves 

 and current systems. The Instrument consists of 

 cups which trap the wind and cause a shaft to 

 rotate. A cap is locked to the shaft and acts as 

 a light chopper. The light source is an incan- 

 descent bulb within a housing having a single slot. 

 A photoelectric switch is placed in line with the 

 slot. The chopper rotates between the lamp housing 

 and the photo detector mount. Thus, as the shaft 

 rotates, light passing the lamp housing slit is al- 

 ternately interrupted and passed by the slots in 

 the chopper causing the photoelectric switch to al- 

 ternately open and close an electric circuit. The 

 rate of switching depends on the wind speed. (30) 



FATA MORGANA. A complex mirage that is character- 

 ized by multiple distortions of images, generally 

 in the vertical, so that such objects as cliffs 

 and cottages are distorted and magnified into fan- 

 tastic castles. The name is due to Italian poets 

 who related this type of mirage . (often seen near 

 the Strait of Messina) to a submarine crystal palace 

 of Fata Morgana (Italian for Morgan le Fay) . 



An unusual density stratification is required 

 to produce this mirage, namely the joint occurrence, 

 in vertically adjacent layers, of density gradients 

 that would give an Inferior mirage and a superior 



h5 



