Tropical Moist Climates (Group A)

Tropical Moist (Group A) climates are found in a band about 15º to 25º N and S of the equator. What climate characteristics is the tropical moist climate group likely to have?

  • Temperature: Intense sunshine; each month has an average temperature of at least 18 ºC (64 ºF).
  • Rainfall: Abundant, at least 150 cm (59 inches) per year.


Tropical Rainforest (Af)

A dense forest. The trees are covered in vegetation. The wet tropics have almost no annual temperature variation and tremendous amounts of rain fall year round, between 175 and 250 cm (65 and 100 inches). These conditions support the tropical rainforest biome. Tropical rainforests are dominated by densely packed, broadleaf evergreen trees. These rainforests have the highest number of species or biodiversity of any ecosystem.

Tropical Monsoon (Am)

The tropical monsoon climate has very low precipitation for several months each year (during the dry winter monsoon), but very heavy precipitation during the wet summer monsoon. Rainforests grow here because the dry period is short, and the trees survive off of soil moisture from the abundant summer rains. This climate is found where the monsoon winds blow, primarily in southern and southeastern Asia and western Africa.

Tropical Savanna (Aw)

Also called tropical wet and dry, this climate lies between about 5º and 20º latitude, between the ITCZ and the STH pressure belts. In the northern hemisphere, when the ITCZ drifts northward in the summer, the zone is wet. In the winter, when the ITCZ moves back toward the equator, STH pressure shifts southward over this region, so the region is dry. Because of having several months of low rainfall, it is usually not wet enough to support forest, so the typical vegetation is savanna. This biome consists mostly of tall grasses, with widely scattered deciduous trees and rare areas of denser forests.

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