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

(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.