Harmattan

The Harmattan is a season in West Africa that occurs between the end of November and the middle of March. It is characterized by a dry and dusty northeasterly trade wind, of the same name, which blows from the Sahara over West Africa into the Gulf of Guinea. The name is related to the word haramata in the Twi language. The temperature is cold usually at night but can be very hot in certain places during the day. Generally, temperature differences can depend on local circumstances. The Harmattan blows during the dry season, which occurs during the months with the lowest sun. In this season, the subtropical ridge of high pressure stays over the central Sahara and the low-pressure Intertropical Convergence Zone (ITCZ) stays over the Gulf of Guinea. On its passage over the Sahara, the Harmattan picks up fine dust and sand particles (between 0.5 and 10 micrometres). It is also known as the "doctor wind", because of its invigorating dryness compared with oppressive humid tropical air.