(a) Describe the characteristics of the equatorial climate. (b) Highlight the main features of the vegetation type associated with the climatic region in (a...

Answer Details

(a) Characteristics of the equatorial climate

• High temperatures all year round: Mean monthly temperatures are about 27 C, with a very small annual range (about 2 to 3 C) because the sun is nearly overhead throughout the year.
• Heavy rainfall: Rainfall is high, usually over 2000 mm a year, and is well distributed over all the months (no real dry season), often with two maxima following the overhead sun.
• Convectional rainfall: Rain falls mainly in the afternoon as heavy convectional thunderstorms, often preceded by a hot, sticky morning.
• High relative humidity: Humidity is very high (about 80 per cent or more), making the weather hot and uncomfortable.
• Small diurnal and annual temperature range; cloudy skies and light, variable winds (doldrums).

(b) Main features of the vegetation (tropical/equatorial rainforest)

• The vegetation is dense evergreen tropical rainforest because the hot, wet conditions allow continuous growth all year.
• Trees are tall, with straight trunks, and are arranged in layers (storeys), the tallest reaching over 45 metres and forming a closed canopy that shuts out sunlight from the forest floor.
• There is a great variety of tree species (hardwoods such as mahogany, ebony and iroko) growing mixed together rather than in pure stands.
• Trees have broad leaves, buttress roots and drip-tips; climbers (lianas) and epiphytes grow on the tall trees.
• Because sunlight cannot reach the floor, undergrowth is thin except along rivers and clearings; along the coast and river mouths there is mangrove forest.