LITRE . The 12th General Conference on Weights and 

 Measures (Oct. 1964) abolished the 1901 definition 

 of the litre based on the volume occupied by 1 

 kilogramme of water. This decision was accompanied 

 by a declaration that the word "litre" can be used 

 as a special name given to the cubic decimetre and 

 by a recommendation that the name "litre" shall 

 not be used to express the results of volume 

 measurements of high precision. The litre of 1901 

 has been experimentally established to be equal to 

 1.000028 cubic decimetre. For scientific and 

 technological purposes the cubic metre, its multiples 

 and submultiples constitute the sole references for 

 volume measurements in the International System of 

 Units. Use of the litre and its submultiples, such 

 as the centilitre and the millilitre, will hence- 

 forth tend to fall into disuse except for ordinary 

 transactions in trade. 



LITTLE BROTHER . A secondary tropical cyclone some- 

 times following a more severe disturbance. (17) 



LITTORAL . Of or pertaining to a shore, especially 

 of the sea. A coastal region. (11) 



LITTORAL DEPOSITS . Deposits of LITTORAL DRIFT. 

 (11) 



LITTORAL DRIFT . The material that moves in the 

 LITTORAL ZONE under the influence of waves and 

 currents. (27) 



LITTORAL TRANSPORT . The movement of material along 

 the shore in the LITTORAL ZONE by waves and currents . 

 (11) 



LITTORAL ZONE . Areas of the ocean bottom reached 

 by sufficient light to support the growth of plant 

 life. (27) 



LOAD ADMITTANCE . Load admittance may be defined 

 as the reciprocal of the load impedance. (4) 



LOAD CURRENT . The load current of an energy load 

 is the rms current through the terminals of that 

 load when connected to a specified source. (4) 



LOAD IMPEDANCE . The load impedance of an energy 

 load is the impedance which would be measured at 

 the terminals of that load if they were not con- 

 nected to a source. (4) 



LOAD POWER . The load power of an energy load is 

 the average rate of flow of energy through the 

 terminals of that load when connected to a speci- 

 fied source. (4) 



LOAD TRANSITION LOSS . The load transition loss at 

 the junction between the energy load and a trans- 

 ducer connecting that load to an energy source is 

 the transmission loss measured by the ratio of the 

 output power of the transducer to the load power 

 of the load. (4) 



LOAD VOLTAGE . The load voltage of an energy load 

 is the rms voltage between the terminals of that 

 load when connected to a specified source. (4) 



LOBES . If a three-dimensional representation of a 

 transducer directivity is made by rotating the two- 

 dimensional directivity pattern these sectors gen- 

 erate zones, or regions, on the constant distance 

 surface. These regions are known as lobes. The 

 term is also used with reference to the correspond- 

 ing portions of the directivity pattern. The 

 region, or sector, which includes the reference 

 axis is known as the primary lobe; the remaining 

 regions, or sectors, are known as the secondary 

 lobes . When the primary lobe is the only lobe 

 showing maximum response it is often called the 

 major lobe. In that case the secondary lobes are 

 called minor lobes. (4) 



LOCH . 1. A lake. 



2. An arm of the sea, especially when 

 nearly landlocked (Scotland) . (17) 



LOCO . Long Core Drilling Program. 



LOESS . A buff -colored, unstratified deposit rang- 

 ing in grain size from clay to fine-grain sand and 

 distributed and deposited by wind action. (27) 



LOGARITHMIC DECREMENT . The logarithmic decrement 

 is the natural logarithm of the ratio of any two 

 successive amplitudes of like sign, in the decay 

 of a single-frequency oscillation. (2) 



LOG LINE . A graduated line used to measure the 

 spee'd of a vessel through the water or to measure 

 the velocity of the current from a vessel at an- 

 chor. (24) 



LONG CRESTED WAVES . Waves having crests which are 

 long compared to the wavelength. 



LONGITUDE . Angular distance in a great circle of 

 reference reckoned from an accepted origin to the 

 projection of any point on that circle. Longitude 

 on the earth's surface is measured in the equator 

 east and west of the meridian of Greenwich and may 

 be expressed either in degrees or in hours, the 

 hour being taken as the equivalent of 15° of longi- 

 tude. Celestial longitude is measured in the eclip- 

 tic eastward from the vernal equinox. The mean 

 longitude of a celestial body moving in an orbit 

 is the longitude that would be attained by a point 

 moving uniformly in the circle of reference at the 

 same average angular velocity as that of the body 

 and with the initial position of the point so taken 

 that its longitude would be the same as that of the 

 body at a certain specified position in its orbit. 

 With a common initial point, the mean longitude of 

 a body will be the same in whatever circle it may 

 be reckoned. (14) 



LONGITUDINAL WAVE . A longitudinal wave is a wave 

 in which the direction of displacement of each par- 

 ticle in the medium is perpendicular to the wave 

 itself. Sound waves in air or water are longitudi- 

 nal waves . (9) 



LONGSHORE BAR . A BAR which extends generally 

 parallel with the shoreline and is submerged at 

 least by high tides. (27) 



LONGSHORE CURRENT (LITTORAL CURRENT) . The result- 

 ant current produced by waves being deflected at an 

 angle by the shore. In this case the current runs 

 roughly parallel to the shoreline. 



The longshore current is capable of carrying 

 a certain amount of material as long as its velocity 

 remains fairly constant; however, any obstruction, 

 such as a submarine rock ridge or a land point cut- 

 ting across the path of the current will cause 

 loss of velocity and consequent loss of carrying 

 power. (24) 



LONG WAVE . Waves under conditions where the rela- 

 tive depth is less than 0.05, and where the phase 

 velocity is dependent upon water depth, but indepen 

 dent of wave length. 



LOOMING . A common form of mirage. The appearance 

 in the sky or on the horizon of objects that are 

 normally hidden below the horizon is a common oc- 

 currence in the Far North. Images, sometimes up- 

 side down, may appear well up in the sky, resting 

 on a pedestal or floating just above the horizon. 

 The opposite, known as sinking, causes nearby 

 objects which should be in clear view to disappear. 

 Looming may interfere with the identification 

 of landmarks by distortion, may make estimation of 

 vertical distances more difficult, may cause ICE- 



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