Worldwide zones of Tropical rainforest climate (Af).
A tropical rainforest climate, humid tropical climate or equatorial climate is a tropical climate sub-type usually found within 10 to 15 degrees latitude of the equator. There are some other areas at higher latitudes, such as the coast of southeast Florida, USA, and Okinawa, Japan that fall into the tropical rainforest climate category. They experience high mean annual temperatures, small temperature ranges, and rain that falls throughout the year. Regions with this climate are typically designated Af by the Köppen climate classification. A tropical rainforest climate is typically hot, very humid, and wet.
Borneo, with the typical vegetation of tropical forest.
Tropical rain forests have a type of tropical climate in which there is no dry season—all months have an average precipitation value of at least 60 mm (2.4 in). There are no distinct wet or dry seasons as rainfall is high throughout the months. One day in a tropical rainforest climate can be very similar to the next, while the change in temperature between day and night may be larger than the average change in temperature during the year.
Equatorial climates and tropical trade-wind climates
When tropical rainforest climates are more dominated by the Intertropical Convergence Zone (ITCZ) than the trade winds (and with no or rare cyclones), so usually located near the equator, they are also called equatorial climates. Otherwise, when they are more dominated by the trade winds than the ITCZ, they are called tropical trade-wind climates. In pure equatorial climates, the atmospheric pressure is almost constantly low so the horizontal pressure gradient is low. Consequently, the winds are rare and usually weak (except sea and land breezes in coastal areas) while in tropical trade-wind climates, often located at higher latitudes than the equatorial climates, wind is almost permanent which incidentally explains why rainforest formations are impoverished compared to those of equatorial climates due to their necessary resistance to strong winds accompanying tropical disturbances.