The scheme

GROUP A: Tropical/megathermal climates

• Tropical rain forest climate (Af): All twelve months have average precipitation of at least 60 mm (2.36 inches). 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. This climate is dominated by the Doldrums Low Pressure System all year round, and therefore has no natural seasons.
  Examples:
  Singapore
  Belém, Brazil.
  • Some of the places that have this climate are indeed uniformly and monotonously wet throughout the year (for example, the northwest Pacific coast of South and Central America, from Ecuador to Costa Rica, see for instance, Andagoya, Colombia), but in many cases the period of higher sun and longer days is distinctly wettest (as at Palembang, Indonesia) or the time of lower sun and shorter days may have more rain (as at Sitiawan, Malaysia).
  • A few places with this climate are found at the outer edge of the tropics, almost exclusively in the Southern Hemisphere; one example is Santos, Brazil.
    Note. The term aseasonal refers to the lack in the tropical zone of large differences in day light hours and mean monthly (or daily) temperature throughout the year. There are annual cyclic changes in the tropics, not as predictable as those in the temperate zone, albeit unrelated to temperature but to water availability whether as rain, mist, soil, or ground water. Plant response (e. g., phenology), animal (feeding, migration, reproduction, et cetera), and human activities (plant sowing, harvesting, hunting, fishing, et cetera) are tuned to this seasonality. Indeed, in tropical South America and Central America, the rainy season (and the high water season) is called Invierno or Inverno, even though it could occur in the northern hemisphere summer; likewise, the dry season (and low water season) is called Verano or Verão and can occur in the northern hemisphere winter.