Tropical rainforest climate (Af) is a low-latitude climate that is being controlled by equatorial tropical air masses and the climate on eastern sides of continents are influenced by maritime tropical air masses.
These air masses flow out from the moist western sides of oceanic high-pressure cells, and bring lots of summer rainfall. The summers are warm and very humid. It also rains a lot in the winter.
These climates usually occur within 5–10° latitude of the equator. In some eastern-coast areas, they may extend to as much as 25° away from the equator because of the moderating influence of the oceans on coastal temperatures. This climate is dominated by the Doldrums Low Pressure System all year round, and therefore has no natural seasons.
The Köppen Climate Classification System is the most widely used system for classifying the world's climates.
Its categories are based on the annual and monthly averages of temperature and precipitation. The Köppen system recognizes five major climatic types; each type is designated by a capital letter (A, B, C, D, and E). These are subdivided, with additional letters again used to designate the various subtypes. See table below:
Köppen Climate Classification via kwout