nautical mile

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nautical mile

1. a unit of length, used esp in navigation, equivalent to the average length of a minute of latitude, and corresponding to a latitude of 45?, i.e. 1852 m (6076.12 ft.)
2. a former British unit of length equal to 1853.18 m (6080 ft.), which was replaced by the international nautical mile in 1970

nautical mile

[′nȯd·ə·kəl ′mīl]
(navigation)
A unit of distance used principally in navigation; for practical consideration it is usually considered the length of 1 minute of any great circle of the earth, the meridian being the great circle most commonly used; the International Hydrographic Bureau in 1929 proposed a standard length of 1852 meters, which is known as the international nautical mile.

nautical mile

nautical mileclick for a larger image
Nautical mile.
A common unit for measuring distance. For most practical navigation purposes, all of the following units are used interchangeably as the equivalent of one nautical mile: (a) 6076.11549 ft or 1852 m; (b) one minute of arc of a great circle on a sphere having an area equal to that of the earth; (c) one minute of arc on the earth's equator, or 6076.10 ft (1851.9952 m); (d) one minute of arc of the meridian or one minute of latitude. This, however, varies between 1843 m (6046.58793 ft) at the equator, 1853 m (6079.3963 ft) at 45°N and S latitude, and 1862 m (6108.9238 ft) at the poles because the earth is an oblate spheroid. However, for the purpose of navigation, the International Nautical Mile of 1852 m (6076.1033 ft) has been adapted as the standard for air navigation.