The Tropic of Cancer lies approximately along latitude 23° 30′ N. Around 21–2 June, the sun’s rays are perpendicular to the ground along this line and the sun exerts its maximum strength in the Northern Hemisphere. Conversely, the sun is overhead at the approximate latitude of 23° 30′ S, the Tropic of Capricorn, on 22–3 December when the sun’s heat is at its maximum in the Southern Hemisphere. Between these two lines of latitude lie the tropics. In America this zone is known as the neotropics and in Africa and South-East Asia as the palaeotropics.