Harmattan Series

The season is on us again, or at least we are beginning to get its feeling. The more we know about it, the better we are prepared for it. DQB will be running a mini-series on it to help us get on like it was never there...

     The Harmattan is a hot, dry and dusty wind (continental trade wind) blowing over West Africa. This northeasterly wind blows from the Sahara Desert into the Gulf of Guineabetween the end of November and the middle of March (winter).^[1] The name comes from or is related to an Akancognate.^[2]

On its passage over the desert, it picks up fine dust and sand particles (between 0.5 and 10 micrometres). The air is particularly dry and desiccating when the Harmattan blows over the region. At morning, low temperatures can easily be as low as 15 °C (59 °F) or 20 °C (68 °F). At afternoon, high temperatures easily soar to more than 30 °C (86°F) and can reach as high as 40 °C (104 °F) sometimes, while the relative humidity drops under 10%.

The Harmattan blows during the dry season which occurs during the lowest-sun months, when a high pressure system of thesubtropical ridge stays over the central Sahara Desert and when a low pressure system of the Intertropical Convergence Zone (ITCZ) stays over the Gulf of Guinea. The Harmattan brings desert-like weather conditions: it lowers the humidity, dissipates cloud cover, prevents rainfall formation and sometimes creates big clouds of dust or sand which can even result in violentduststorms or sandstorms but when the haze effect is weak, this dry wind creates beautiful sunny days with plenty of clear skies.