Latitude: Meaning (information, definition, explanation, facts)

Latitude, denoted φ, gives the location of a place on Earth north or south of the Equator. Latitude is an angular measurement ranging from 0° at the Equator to 90° at the poles.

Usually, the difference in latitude largely affects the climate and/or weather of regions.

Other latitudes of particular importance are the Tropic of Cancer (latitude 23°27' north), the Tropic of Capricorn (latitude 23°27' south), the Arctic Circle (latitude 66°33' north), and the Antarctic Circle (latitude 66°33' south). 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.

All locations of a given latitude are collectively referred to as a line of latitude or parallel, because they are coplanar, and all such planes are parallel to the Equator. A line of latitude is approximately a small circle on the surface of the Earth; except at the Equator, it is not a geodesic since the shortest route between two points at the same latitude usually involves moving further away from the equator.

Latitude more loosely determines tendencies in climate, polar auroras, prevailing winds, and other physical characteristics of geographic locations.

Each degree of latitude is further sub-divided into 60 "minutes". In navigation a minute may be sub-divided into tenths. Thus a fully qualified latitude may be expressed thus; 23° 27'.5 S

A specific latitude may then be combined with a specific longitude to give a precise position on the Earth's surface.

One minute of arc of latitude is approximately one nautical mile.

Colatitude is the complement of latitude.

In common usage "latitude" refers to geodetic or geographic latitude φ and is the angle between a plumb line and the equatorial plane—because it originated as the angle between horizon and pole star. Because the Earth is slightly flattened by its rotation, cartographers refer to a variety of auxiliary latitudes to precisely adapt spherical projections according to their purpose.

The expressions following assume elliptical polar sections with eccentricity e, and that all sections parallel to the equatorial plane are circular. Geographic latitude (with longitude) then provides a Gauss map.

Geocentric latitude φ_g is probably what's generally thought to be meant by latitude. It is the angle between the plane of the equator and the radial line.

tanφ_g = (1 - e²)tanφ

Rectifying latitude μ is the surface distance from the equator, scaled so the pole is "90°". Unfortunately, it is an incomplete elliptic integral:

Reduced or parametric latitude η is the latitude of the same radius on the sphere with the same equator.

Authalic latitude β gives an area-preserving transform to the sphere.

where

Conformal latitude χ gives an angle-preserving (conformal) transform to the sphere.

Further reading

• John P. Snyder Map Projections: a working manual USGS