R 



RACE . A rapid current or a constricted channel in 

 which such a current flows. The term is usually 

 used only in connection with a tidal current, when 

 it may be called a tide race. (17) 



RADAR . The name radar is derived from the words. 

 Radio Detection and Ranging. 



Radar is a system of determining the distance 

 of an object by measuring the interval of time be- 

 tween transmission of a radio signal and reception 

 of a signal returned as an echo, or by a transmit- 

 ter triggered by the outgoing signal. The bearing 

 of the object may be determined by noting the orien- 

 tation of the directional antenna. (17) 



RADIATION . The transmission of heat by invisible 

 waves not unlike radio waves. Every warm object 

 puts out such waves; and if an object is hot 

 enough, it will also produce similar waves which 

 we recognize as light. Although a diver will 

 also lose some heat by radiation, the amount is 

 very small compared to the loss by conduction. (37) 



RADIOACTIVITY METER FOR LIQUIDS . A device developed 

 by the U. S. Naval Applied Science Laboratory moni- 

 tors the gross beta activity of drinking water, 

 boiler water, and other liquids aboard nuclear 

 powered ships. Called "Evaporation and Concentra- 

 tion Unit for Dilute Radioactive and Non-Radioac- 

 tive Solutions", it evaporates a given mass of 

 sample liquid and the solid remnants are evenly 

 arranged on a small disk surface allowing accurate 

 geiger-muller radiation measurement. (30) 



RADIOBEACON BUOY . A buoy equipped with a marker 

 radiobeacon. Such a buoy is usually used to mark 

 an important entrance to a channel. The beacon is 

 of low power, providing a signal for a short range. 

 (17) 



RADIO CURRENT METER . An instrument for observing 

 currents developed by the Coast and Geodetic Sur- 

 vey. It operates from an anchored buoy from which 

 signals indicating the velocity and direction of 

 the current are automatically transmitted by radio 

 to a conveniently located recording station. The 

 Roberts Radio Current Meter Operating Manual, is- 

 sued by the Coast and Geodetic Survey, contains a 

 detailed description of the meter and auxiliary 

 equipment. (14) 



RADIOISOTOPE . See ISOTOPE. 



RADIOIARIA . Minute marine protozoans which have a 

 siliceous skeleton of spicules and radiating thread- 

 like pseudopodia. Radiolarian ooze contains large 

 proportions of radiolarian skeletons and is an im- 

 portant constituent of the deep ocean deposits. 

 Radiolarian ooze is classed as mud on bottom sedi- 

 ment charts . (16) 



RADIOMETER . This instrument is essentially a heat 

 flow meter used to measure long wave radiation as 

 well as solar radiation. It can be used both for 

 daytime and nighttime measurements and to measure 

 the net heat transfer through a surface. 

 See also GEIR AND DUNKLE RADIOMETER. 



RADIOSONDE . A balloon-borne instrument for the 

 simultaneous measurement and transmission of 

 meteorological data. (31) 



RAF OS . Rafos is a long range navigation system. 

 Rafos, the reverse spelling of SOFAR, uses this 

 acronym since the system is the direct reverse of 

 the sofar system. In rafos, explosive charges are 

 released at fixed shore stations and the time of 

 release is known. For example, the charges could 

 be exploded once an hour, exactly on the hour. 

 The ship would time the arrival of each of the 

 explosive sound waves and thus would have the 

 transit time for each such wave. This information 

 and the average velocity would enable the ship to 

 compute its distance from the shore stations. (29) 



RAFTED ICE . A type of PRESSURE ICE formed by one 

 CAKE overriding another, or RAFTING. Rafted ICE 

 has well defined contours and when observed may be 

 regarded as a relatively recent occurrence. (25) 



RAFTING . 1. The overriding of one ice cake on 

 another as a result of pressure. See BENDING, 

 TENTING. 



2. The transporting of sediment, rocks, 

 silt, and other matter of land origin out to sea 

 by ice, logs, etc., with subsequent deposition of 

 the rafted matter when the carrying agent disinte- 

 grates. (17) 



RAM . The sloping, underwater ledge of an ICEBERG 

 or of a GLACIER terminus bathed in water. More 

 rapid melting at the water line than above and 

 below causes a notch to be formed at the water line 

 below which is the ram. As a result of underwater 

 CALVING, the ram may become detached and is then 

 buoyed up to the surface. This process can be a 

 serious hazard for boats, even of large size, in 

 the immediate vicinity. (25) 



RAMP . Solid material forming an incline between 

 two levels, such as an accumulation of snow form- 

 ing an inclined plane between land or land ice and 

 sea ice or shelf ice. Also called drift ice foot. 

 (17) 



RANA . Rana is a medium range surveying phase com- 

 parision system developed by the French for their 

 hydrographic surveys in North Africa. It is quite 

 similar to LORAC. Through the use of 4 radio fre- 

 quencies with certain relationship, the difference 

 in frequency results in lane widths at the base 

 line of 200 meters, 4 kilometers, and 80 kilometers. 

 The 4 radio frequencies are so chosen that a dif- 

 ference frequency is selected from a combination 

 of two of the frequencies. For the fine lane of 

 200 meters, the fundamental frequency of 1600 

 kilocycles is used for phase comparison. Then a 

 difference frequency of 80 kilocycles produces 

 lanes of 4 kilometers while a difference in fre- 

 quency of 4 kilocycles produces lanes 80 kilometers 

 wide at the base line. (29) 



RANDOM NOISE . Random is a word which is used to 

 denote the idea of unpredictability. Thus we may 

 know the magnitude of a sound or oscillation at a 

 given moment, but this in no sense allows us to 

 predict what it will be even a short time ahead, 

 except perhaps in a statistical sense. (9) 



RANGE COMPREHENSION . The difference between the 

 minimum and maximum ranges of an FM sonar system. 

 (5) 



RANGE OF TIDE . The difference in height between 

 consecutive high and low waters. The mean range 

 is the difference in height between mean high water 

 and mean low water. The great diurnal range or 

 diurnal range is the difference in height between 

 mean higher high water and mean lower low water. 

 I'Jhere the type of tide is diurnal the mean range 

 is the same as the diurnal range. For other ranges 



96 



