Latitude

Latitude is the angular distance of a point on the earth's surface, measured in degrees from the centre of the earth. It is parallel to a line, the equator, which lies midway between the poles. These lines are therefore called parallels of latitude, and on a globe are actually circles becoming
smaller polewards. The equator represents 0 degrees and the North and South Poles are 90 degrees North and 90 degrees South. Between these points lines of latitude are drawn at intervals of 1 degrees. For precise location on a map, each degree is subdivided into 60 minutes and each minute into 60 seconds. The most important lines of latitude are the equator, the Tropic of Cancer (23 and half degrees North), and Tropic of Capricorn (23 and half degrees South), the Arctic Circle (66 and half degrees North) and the Antarctic Circle (66 and half degrees South). As the earth is slightly flattened at the poles, the linear distance of a degree of latitude at the pole is a little longer than that at the equator. For example, at the equator (0 degree) it is 110 km, at 45 degrees it is 111 km and at the poles it is 111.7 km. The average is taken as 111 km. This is a useful figure and can be used for calculating distances at any place. Cairo is 30 degrees North; it is therefore 30 x 111 or 3330 km from the equator.