Latitude

Latitude (also called lool or loolal in Somali) is a geographic measurement that indicates the distance of a location on Earth's surface from the equator, dividing the globe into north and south. It is measured in degrees (°), starting from 0° at the equator and reaching 90° at the North Pole and 90° at the South Pole. Each degree is subdivided into minutes and seconds, or can be expressed as a decimal fraction.

Latitude alone is insufficient to determine a location. It must be combined with longitude, the east-west measurement. These two coordinates together form the geographic coordinate system used to identify any place on Earth.

Lines of latitude

Lines of latitude are drawn on maps running east to west and parallel to each other. For this reason they are also called parallels, since they never intersect. The 0° line is the equator, and it is the only one that is a great circle; all others diminish in size as they approach the poles, where they become a single point.

Notable lines

Certain lines of latitude have been given special names, such as the Tropic of Cancer in the north and the Tropic of Capricorn in the south, which mark the farthest points at which the sun can pass directly overhead during the year. There are also the Arctic and Antarctic circles near the poles, which define regions of midnight sun and polar night. These designations are not based on political boundaries but are tied to Earth's orientation in its orbit.

Climate and latitude

Latitude significantly affects the intensity of solar radiation reaching a location. Near the equator, solar rays strike at angles nearly perpendicular to the surface, producing high temperatures and little seasonal variation. As one moves to higher latitudes, the rays become more oblique, spreading energy over a larger area, and the sun's height decreases. Consequently, latitude is one of the most important factors determining climate patterns.

Measurement and modern use

Historically, latitude was measured using instruments such as the sextant, by observing the position of the sun or stars relative to the horizon. Today, satellite systems such as GPS provide latitude and longitude rapidly and with high precision. Accurate calculation requires specifying the reference datum being used, since Earth is not a perfect sphere.