TOTAL ICE SEASON. mNIHUM . The shortest Ice season 

 recorded over a period of years In an area. See 

 ICE PERIOD. 



TOTAL LUNG CAPACITY . The total volume of air that 

 the lungs can hold when filled to capacity. It is 

 normally between 5 and 6 liters. (A liter is about 

 the same as a quart. It is the standard unit of 

 volume in the metric system, which is generally 

 used in physiological measurements. (37) 



TOTO . Tongue of the Ocean. See AUTEC. 



TOWING HAWSER . See WIRE ROPE. 



TRADES . See TRADE WINDS. 



TRADE WINDS (TRADES) . The wind system, occupying 

 most of the tropics, which blows from the SUB- 

 TROPICAL HIGHS toward the EQUATORIAL TROUGH; a 

 major component of the general circulation of the 

 atmosphere. The winds are northeasterly in the 

 Northern Hemisphere and southeasterly in the 

 Southern Hemisphere; hence they are known as the 

 northeast trades and southeast trades, respectively. 



The trade winds are best developed on the 

 eastern and equatorial sides of the great subtropi- 

 cal highs, especially over the Atlantic. In the 

 Northern Hemisphere they begin as north-northeast 

 winds at about latitude 30° in January and latitude 

 35° in July, gradually veering to northeast and 

 east -northeast as they approach the equator. Their 

 southern limit is a few degrees north of the 

 equator. The southeast trades occupy a comparable 

 region in the Southern Hemisphere, and similarly 

 change from south-southeast on their poleward side 

 to southeast near the equator. In the Pacific, 

 the trade winds are properly developed only in the 

 eastern half of that ocean; and in the Indian Ocean, 

 only south of about 10°S. They are primarily sur- 

 face winds , their usual depth being from 3000 to 

 5000 feet, although they sometimes extend to much 

 greater altitudes. They are characterized by great 

 Constance of direction and, to a lesser degree, 

 speed; the trades are the most consistent wind 

 system on earth. (14) 



TRAFFIC NOISE . By traffic noise is meant the gen- 

 eral disturbance due to ships which is not as- 

 sociated with a specific vessel, or what is more 

 significant, which has no definite directional dis- 

 tribution relative to a given observation point and 

 which shows little change in intensity with change 

 in position. (4) 



TRAINING WALL . See JETTY. 



TRAMONTANA . A northeasterly or northerly wind oc- 

 curring in winter off the west coast of Italy. It 

 is a fresh wind of the fine weather mistral type. 

 (17) 



TRANSDUCER . Any device for converting energy from 

 one form to another (electrical, mechanical, or 

 acoustic). In sonar, usually combines the func- 

 tions of a hydrophone and a projector. (5) 



TRANSDUCER LOSS . The transducer loss of a trans- 

 ducer connecting an energy source and an energy 

 load is the transmission loss measured by the ratio 

 of the source power of the source to the load power 

 of the load. (4) 



TRANSFER ADMITTANCE . The transfer admittance of a 

 network made up of an energy source and an energy 

 load connected by a transducer is the quotient ob- 

 tained by dividing the phasor representing the 

 source current of the source by the phasor repre- 

 senting the load voltage of the load. (4) 



TRANSFER IMPEDANCE . The transfer impedance of a 

 network made up of a given source and a given load 

 connected by a given transducer is the quotient ob- 



tained by dividing the phasor representing the 

 source voltage of the source by the phasor repre- 

 senting the load current of the load. (4) 



TRANSIENT VIBRATION . Transient vibration is tem- 

 porarily sustained vibration of a mechanical system. 

 It may consist of forced or free vibration or both. 

 (2) 



TRANSIT. Program to develop and establish in 

 being a system of near-earth satellites to provide 

 a means for establishing locations (navigating) 

 anywhere on the surface of the earth. (35) 



TRANSITIONAL WATER (TRANSITIONAL ZONE) . In regard 

 to progressive gravity waves, water whose depth is 

 less than 1/2 but more that 1/25 the wave length. 

 Often called SHALLOW WATER. (11) 



TRANSITION LOSS . The transition loss at the junc- 

 tion between an energy source and an energy load is 

 the transmission loss measured by the ratio of the 

 source power of that source to the load power of 

 that load . (4) 



TRANSMISSIBILITY . Transmissibility is a term which 

 is used to describe the ability of a system either 

 to amplify or to suppress an input vibration. More 

 technically, it is the ratio of the response amp- 

 litude of the system in steady-state forced vibra- 

 tion to the excitation amplitude. The ratio may be 

 between forces, displacements, velocities, or ac- 

 celerations. (9) 



TRANSMISSION ANOMALY . The difference (in decibels) 

 between the total transmission loss in intensity 

 and the reduction in intensity due to an assumed 

 inverse square divergence. (5) 



TRANSMISSION GAIN . Whenever the TRANSMISSION FAC- 

 TOR is a number greater than unity, as it is in 

 the case of an amplifier, the transmission loss 

 would have a negative sign. In such cases the 

 logarithm of the reciprocal of the transmission fac- 

 tor is written with a positive sign and designated 

 as a transmission gain. (4) 



TRANSMISSION LEVEL . The transmission level of the 

 energy at any point in an energy transmission sys- 

 tem is the rate of flow of that energy as expressed 

 in terms of (1) a specified reference rate of flow 

 and of (2) the transmission loss by which the actual 

 rate of flow must be reduced to equal the reference 

 rate. (4) 



TRANSMISSION LOSS . Transmission loss is the reduc- 

 tion in the magnitude of some characteristic of a 

 signal between two stated points in a transmission 

 system. (9) 



TRANSMISSOMETER . A light-path device for measuring 

 in situ turbidity by relative light scattering and 

 absorption of light transmitted. (35) 



TRANSMITTING BAND RESPONSE . The transmitting band 

 response of a sonar projector, for a given bearing 

 and for a given frequency band, may be defined as 

 the response measured by the quotient obtained by 

 dividing (1) the index intensity of the acoustic 

 energy radiated on the given bearing and in the 

 given frequency band by the projector when receiv- 

 ing electric energy occupying the same frequency 

 band by (2) the power of this received electric 

 energy. (4) 



TRANSMITTING DIRECTIVITY FACTOR . 1. The transmit- 

 ting directivity factor of a sonar transducer, for 

 a specified frequency, may be defined as the ratio 

 of (1) the power per unit band of the acoustic ener- 

 gy radiated over all bearings and at the specified 

 frequency by the transducer when receiving electric 

 energy having a given power per unit band at the 

 specified frequency to (2) the power per unit band 

 of the acoustic energy which would be radiated over 



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