Temperature remains high in tropical region throughout the year. Maximum rainfall occurs on the eastern coasts of the continents which decreases westwards
The map below shows the areas within the tropics which have all 12 months of the year with temperatures above 18 °C. The three types of tropical climate are classified as Tropical Rainforest or Equatorial (Af), Tropical Monsoon (Am) and Tropical Wet and Dry or Savannah (Aw). As can be observed in the map these three tropical climates are confined to a global band known as the Tropics which falls between the northern latitude of Tropic of Cancer and the sourther latitude, Tropic of Capricorn. The general pattern of the tropical climate is warm temperatures. Depending on the type of tropical climate, humidity is variable with Equatorial climates experiencing large quantities of precipitation all year round and Tropical Wet and Dry and Tropical Monsoon climates expereincing seasonal shifts in rain patterns.
THE TROPICAL CLIMATE CONTROL
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The most important climate control in regard to the tropical climate types relates to the position of the Inter Tropical Convergent Zone or ITCZ. The ITCZ is an area of low pressure and marks the point of trade wind convergence. These two roles make it an important ingredient in atmospheric circulation and give it a critical role in the formation of the Hadley cell.
The ITCZ's location varies throughout the year and while it remains near the equator, the ITCZ over land drifts farther north or south than the ITCZ over oceans. This is due to greater variation of land temperatures. The location of the ITCZ can vary as much as 40° to 45° of latitude north or south of the equator based on the pattern of land and ocean. Despite these variations the ITCZ relates closely to the altitude of the sun and marks the point where the sun is highest in the sky. In temperate latitudes relative migration of the sun between the Tropic of Cancer and Tropic of Capricorn is responsible for creating the seasons but in tropical latitudes it is responsible for the migration of low pressure and the resullting shifts in seasonal tropical rains. The ITCZ and converging trade winds can be seen in the graphic below. The animation shows the shifting seasonal rains follow the the movement of the ITCZ.