HKDSE Geography/M6/Climate

Most tropical rainforests have tropical maritime climate or equatorial climate. The properties are discussed below.

In this page, we discuss only the general climate of rainforests. Rainforests have a set of distinct microclimates within them, and we will discuss this later.

Insolation and Temperature

Tropical rainforests have the following climatic characteristics:

• Intense insolation, at least 10 hours a day
  • Because they are located in equatorial regions / large angle of the sun due to low latitude
• High annual mean temperature: 26°C
  • Because they are located in equatorial regions / large angle of the sun due to low latitude
• Small diurnal range of temperature - 7-8°C
  • Because the dense cloud cover produces a blanket effect
• Small annual range of temperature - 2-4°C
  • Because of the small annual range of insolation in equatorial areas
    • Result: Lack of seasonality - no distinct winter / cold season

As a result of high insolation, evapotranspiration rate is also high.

Detailed explanations for the above patterns can be found in M7 and E2.

Rainfall

Tropical rainforests have the following rainfall patterns:

• High annual rainfall, above 2000 mm, and exceeds potential evapo-transpiration
• Lack of seasonal patterns in rainfall / no obvious dry season, rainfall is evenly distributed throughout the year
  • Result: Lack of seasonality - no dry season
  • Exception: In tropical monsoon regions, there is more rainfall in summer.

Rain usually occurs as showers or thunderstorms. They are in the form of convection rain, and usually rain in afternoon (where the land receives the most intense sunlight).

Relative Humidity

Tropical rainforests have high relative humidity. We will look at exact numbers in the microclimate section.

Winds

Wind is generally weak in tropical rainforests because the friction of the air is large, due to the dense vegetation cover.

• Exception: In monsoon areas, onshore and offshore monsoon winds are frequent.