In the Köppen climate classification, how many basic types are there within the tropical climate group?

Tropical climate is the first of the five major climate groups in the Köppen climate classification identified with the letter A. A-group regions are usually found in the tropics, below 23.5 latitude in both the southern and northern hemisphere; they include areas around the Equator, Central America, North-central portions of South America, central Africa, southern portions of Asia and parts of North Australia and the Pacific Ocean islands.

Tropical climates are defined by a monthly average temperature of 18 °C (64 °F) or higher in the coolest month, featuring hot temperatures and high humidity all year-round. Annual precipitation is often abundant in tropical climates, and shows a seasonal rhythm but may have seasonal dryness to varying degrees. There are normally only two seasons in tropical climates, a wet (rainy/monsoon) season and a dry season. The annual temperature range in tropical climates is normally very small. Sunlight is intense in these climates.

There are three basic types of tropical climates within the tropical climate group: tropical rainforest climate (Af), tropical monsoon climate (Am) and tropical savanna or tropical wet and dry climate (Aw for dry winters, and As for dry summers), which are classified and distinguished by the precipitation and the precipitation levels of the driest month in those regions.