latitudes

Latitudes are the geographic coordinates that specify how far north or south a location is from the equator. They are defined as angular distances, measured in degrees, minutes, and seconds. The equator represents 0° latitude, while the poles are at 90° north or 90° south. Lines of constant latitude, called parallels, encircle the globe parallel to the equator. The distance represented by one degree of latitude is approximately 111 kilometers near the equator, varying slightly toward the poles due to the Earth's oblate shape.

Geographic latitude, which is the most common form used in maps and GPS, is measured with respect to a reference ellipsoid, a mathematically defined oblate shape approximating the Earth. There is also geocentric latitude, defined as the angle between the equatorial plane and the line from the Earth's center to a point on the surface. Latitudes are typically expressed in decimal degrees or in degrees, minutes, and seconds, with northern latitudes labeled positive and southern latitudes negative.

Latitudes, together with longitudes, form the global coordinate system used for navigation, mapping, and geographic information systems. They underpin time zone boundaries, climate and weather modeling, and regional planning. Certain latitudes mark notable climatic zones and terrestrial belts: the Tropic of Cancer at about 23.5°N and the Tropic of Capricorn at about 23.5°S denote the sun’s most northerly and southerly positions, while the Arctic Circle and Antarctic Circle, near 66.5°N and 66.5°S, delimit polar regions.

The concept has historical roots in ancient astronomy and geometry and remains central to modern geodesy, cartography, and satellite navigation, reflecting how latitude anchors the relationship between location, climate, and the daily cycle of seasons.