The tropical region refers to the areas of the Earth surrounding the equator, between the Tropic of Cancer in the Northern Hemisphere at 23°26′10.3″ N and the Tropic of Capricorn in the Southern Hemisphere at 23°26′10.3″ S. The climate in the tropics is generally hot and humid, with more direct sunlight than the rest of the Earth, and is generally hotter and wetter as it is not affected as much by the solar seasons. The tropical zone includes deserts and snow-capped mountains, which are not tropical in the climatic sense. The tropical zone is the warmest climate zone of the Earth, and it is characterized by areas of "climate radiation". More than 40% of Earths population lives in the tropics. The vegetation in the tropical zone depends on the time during which there is sufficient water available for plants to grow, and it is divided into humid, semi-humid, and arid zones. The humid tropics, which surround the equator with the exception of East Africa and the Andes, are characterized by tropical rainforests, while the semi-humid tropics are characterized by savannah, dry forests, and monsoon forests, which frame the tropical rainforests. The arid tropics are deserts and semi-deserts, where only small changes of temperature occur in the course of the year.