In West Africa, there are two opposing surface air masses. One blowing from the south west and is the equatorial maritime airmass and since it is coming from the ocean, it is humid. Another one is blowing from the north to the east, it is very dry and called harmattan.
Harmanttan isthe tropical continental air mass. It is dry and it comes from the sahara desert.
Where these two winds and air masses meet is an unstable climatic region and it’s called intertropical front.
- It occurs when the moisture droplets merges into larger drops and this happens when the temperature of the cloud decreases. The cloud rise into the cooler layers of the atmosphere. The average annual rainfall in west africa varies as one moves from the coast towards the anterior. Over 2500mm of rain falls annually on much of Sierra Leone Liberia, Niger Delta and around Calabar, may be less than 10 degrees. The seasonal distribution of rain is more important than the mean annual rainfall.
Mean daily temperature in Africa usually varies between 70 degrees to 90 degrees Fahrenheit except during the harmattan. The mean monthly maximum temperature also varies in length when one moves from coast to inland where it becomes 110 degrees Fahrenheit in the north and 90 degrees Fahrenheit in the coastal areas.
Coastal areas of West Africa have a mean monthly relative humidity of about 95% at 6:00am. This will fall to 60% at noon time but towards the north, the relative humidity is 30% at 6°clock in the morning.
it’s a superficial covering of the earth crust and is derived from the underlying parents rock by weathering and organic matter of plant remains.