Chinese English

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.

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.

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.

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.

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.

月球在当地或格林尼治子午线的中天时刻（上中天或下中天）到下一次高潮或低潮时的时间间隔。除非另有规定，此间隔均以当地月中天时间为基准。所有高潮时间间隔的平均数称mean high waterlunitidal interval(平均高潮间隙)，high water intervail（高潮间隙)或corrected establishment（校正朔望高潮间隙）。所有低潮时间间隔的平均数称mean low water lunitidal interval（平均低潮间隙），或low water interval（低潮间隙）。当有显著日潮不等时，用高高潮间隙、低高潮间隙、高低潮间隙和低低潮间隙表示。参见establishment（朔望高潮间隙）。