latitude

Latitude is a geographic coordinate that specifies the north-south position on the Earth's surface. It is defined as the angle between the Earth's equatorial plane and a line from the Earth's center to a point on the surface. Latitudes are measured in degrees, from 0° at the equator to 90° at the poles, with positive values in the northern hemisphere and negative values in the southern hemisphere.

Lines of constant latitude, called parallels, run east-west around the globe. All parallels are circles parallel to the equator; the equator itself is a great circle. Except for the equator, parallels have smaller radii toward the poles, and they never intersect each other.

Latitude can be expressed in degrees, minutes, and seconds or in decimal degrees. One degree equals 60 minutes, and one minute equals 60 seconds. In practice, GPS and many maps use geodetic latitude based on a reference ellipsoid such as WGS84, which accounts for Earth's flattening. Geocentric latitude, the angle at the Earth's center, differs slightly from geodetic latitude.

Certain lines of latitude have special names: the Tropic of Cancer at 23.5°N and the Tropic of Capricorn at 23.5°S mark the northern and southern limits of the Sun's overhead position. The Arctic Circle at about 66.5°N and the Antarctic Circle at about 66.5°S designate regions with extreme variations in daylight.

Latitude is essential in navigation, cartography, geographic information systems, and climate studies. Along with longitude, it locates any place on Earth and helps describe climate zones and daylight patterns.