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Eng ID Term Definition
2981
loxodromic curve
A LOXO­DROME. A RHUMB LINE.
2982
lubber (or lubber's) line
A REFERENCE LINE on any direction-indicating instru­ment, marking the reading which coincides with the HEADING.
2983
lull
A momentary decrease in the SPEED of the WIND.
2984
lumen
The unit of LUMINOUS FLUX in the SI SYSTEM.
2985
luminance (at a point of surface, in a direction)
Quotient of the LUMINOUS INTENSITY, in a given direc­tion, of an in­finitesimal element of the surface containing the point under considerat... more
Quotient of the LUMINOUS INTENSITY, in a given direc­tion, of an in­finitesimal element of the surface containing the point under consideration, by the orthogonally projected area of the element on a plane perpendicular to the given direction.
2986
luminescence
Any emission of light at temperatures below that required for incandescence. See BIOLUMINESCENCE, FLUORESCENCE, PHOSPHORESCENCE.
2987
luminous flux
See FLUX.
2988
luminous intensity
See INTENSITY.
2989
luminous range
See RANGE.
2990
luminous signal
See SIGNAL.
2991
lunar day
See DAY.
2992
lunar distance
The angle, at an observer on the EARTH, between the MOON and another CELESTIAL BODY. This was the basis of a method formerly used to deter­m... more
The angle, at an observer on the EARTH, between the MOON and another CELESTIAL BODY. This was the basis of a method formerly used to deter­mine LONGITUDE at SEA.
2993
lunar eclipse
See ECLIPSE.
2994
lunar inequality
Variation in the MOON's motion in its ORBIT, due to attraction by other bodies of the SOLAR SYSTEM. See EVECTION, PERTURBATION. A minute flu... more
Variation in the MOON's motion in its ORBIT, due to attraction by other bodies of the SOLAR SYSTEM. See EVECTION, PERTURBATION. A minute fluctuation of a MAGNETIC NEEDLE from its mean position, caused by the MOON.
2995
lunar month
See MONTH: SYNODICAL.
2996
lunar rainbow
See MOONBOW.
2997
lunar tide
See under TIDE.
2998
lunation
See MONTH: SYNODICAL.
2999
lunicurrent interval
The interval between the moon's transit (upper or lower) over the local or Greenwich meridian and a specified phase of the tidal current fol... more
The interval between the moon's transit (upper or lower) over the local or Greenwich meridian and a specified phase of the tidal current following the transit. Examples are strength of flood interval and strength of ebb interval, which may be abbreviated to flood interval and ebb interval, re­spectively. The interval is described as local or Greenwich according to whether the reference is to the moon's transit over the local or Greenwich meridian. When not otherwise specified, the reference is assumed to be local.
3000
lunitidal interval
The interval of time between the TRANSIT (upper or lower) of the MOON over the LOCAL or GREENWICH MERIDIAN and the next HIGH WATER or LOW WA... more
The interval of time between the TRANSIT (upper or lower) of the MOON over the LOCAL or GREENWICH MERIDIAN and the next HIGH WATER or LOW WATER at a place. The interval is assumed to be local unless otherwise specified. The average of all high water intervals is called mean high water lunitidal interval, high water interval, or corrected establishment. The average of all low water intervals is called mean low water lunitidal interval, or low water interval. The expressions higher high water interval, lower high water interval, higher low water interval, and lower low water interval are used when there is considerable DIURNAL INEQUALITY. See ESTABLISH­MENT.