The five main latitude regions of Earth's surface comprise geographical zones, divided by the major circles of latitude. The differences between them relate to climate. They are as follows: The North Frigid Zone, between the North Pole at 90° N and the Arctic Circle at 66°33′48.7" N, covers 4.12% of Earth's surface. The North Temperate Zone, between the Arctic Circle at 66°33′48.7" N and the Tropic of Cancer at 23°26'11.3" N, covers 25.99% of Earth's surface. The Torrid Zone, between the Tropic of Cancer at 23°26'11.3" N and the Tropic of Capricorn at 23°26'11.3" S, covers 39.78% of Earth's surface. The South Temperate Zone, between the Tropic of Capricorn at 23°26'11.3" S and the Antarctic Circle at 66°33'48.7" S, covers 25.99% of Earth's surface. The South Frigid Zone, from the Antarctic Circle at 66°33'48.7" S and the South Pole at 90° S, covers 4.12% of Earth's surface. On the basis of latitudinal extent, the globe is divided into three broad heat zones. Torrid Zone The Torrid Zone is also known as the tropics. This zone is bounded on the north by the Tropic of Cancer and on the south by the Tropic of Capricorn; these latitudes mark the northern and southern extremes in which the Sun passes directly overhead. This happens once annually on these cusps, but in the tropics proper, the Sun passes overhead twice a year. Within the northern tropics, the Sun passes overhead its first time for that year before the June solstice, at which time it does so as to the Tropic of Cancer. It passes over these latitudes in turn again, on its apparent southward journey, to and before the September equinox. After then, the center of the Sun at the high point, the zenith, of the sky (which makes for the subsolar point beneath) aligns with successive latitudes in the southern tropics. The Sun passes overhead of these then does so once per year for the Tropic of Capricorn at the December solstice, then passes back again over those latitudes to return to the equator for the March equinox. The Torrid zone includes southern Mexico, Central America, the Caribbean, northern South America (larger parts of Brazil, the Guyanas, Caribbean South America, Andean states and the northern tip of the Southern Cone), the Sudan, the southern regions of Western Sahara, Algeria, Libya and Egypt, West Africa, Central Africa, East Africa, larger parts of Southern Africa