Everything about Latitude totally explained
Latitude, usually denoted symbolically by the Greek letter
phi,
, gives the location of a place on
Earth (or other planetary body) north or south of the
equator.
Lines of Latitude are the horizontal lines shown running east-to-west on maps. Technically, latitude is an
angular measurement in
degrees (marked with °) ranging from 0° at the equator (low latitude) to 90° at the poles (90° N for the
North Pole or 90° S for the
South Pole; high latitude). The
complementary angle of a latitude is called the
colatitude.
Circles of latitude
All locations of a given latitude are collectively referred to as a
circle of latitude or
line of latitude or
parallel, because they're
coplanar, and all such
planes are
parallel to the
equator. Lines of latitude other than the Equator are approximately
small circles on the surface of the Earth; they're not
geodesics since the shortest route between two points at the same latitude involves a path that bulges toward the nearest pole, first moving farther away from and then back toward the equator (see
great circle).
A specific latitude may then be combined with a specific
longitude to give a precise position on the Earth's surface (see
satellite navigation system).
Important named circles of latitude
Besides the equator, four other lines of latitude are named because of the role they play in the geometrical relationship with the Earth and the Sun:
Only at latitudes between the Tropics is it possible for the
sun to be at the
zenith. Only north of the
Arctic Circle or south of the
Antarctic Circle is the
midnight sun possible.
The reason that these lines have the values that they do, lies in the
axial tilt of the Earth with respect to the sun, which is
23° 26′ 21.41″.
Note that the Arctic Circle and Tropic of Cancer and the Antarctic Circle and Tropic of Capricorn are colatitudes since the sum of their angles is 90°.
Subdivisions
To simplify calculations where elliptical consideration isn't important, the
nautical mile was created, equaling exactly 111.12 km per degree of arc or, sub-dividing into
minutes, 1852
metres per minute of arc. One minute of latitude can be further divided into 60 seconds. A latitude is thus specified as 13°19'43″ N (for greater precision, a decimal fraction can be added to the seconds). An alternative representation uses only degrees and minutes, where the seconds are expressed as a decimal fraction of minutes, thus the above example is expressed as 13°19.717' N. Degrees can also be expressed singularly, with both the minutes and seconds incorporated as a decimal number and rounded as desired (decimal degree notation): 13.32861° N. Sometimes, the north/south suffix is replaced by a negative sign for south (−90° for the
South Pole).
Effect of latitude
A region's latitude has a great effect on its
climate and
weather (see
Effect of sun angle on climate). Latitude more loosely determines tendencies in
polar auroras,
prevailing winds, and other physical characteristics of geographic locations.
Researchers at
Harvard's Center for International Development (CID) found in 2001 that only three
tropical economies —
Hong Kong,
Singapore, and
Taiwan — were classified as high-income by the
World Bank, while all countries within regions zoned as
temperate had either middle- or high-income economies.
Elliptic parameters
Because most planets (including Earth) are
ellipsoids of revolution, or
spheroids, rather than
spheres, both the radius and the length of arc varies with latitude. This variation requires the introduction of elliptic parameters based on an ellipse's
angular eccentricity,
(which equals
