Definition

Harmattan, is a cool dry wind that blows from the northeast or east in the western Sahara and is strongest from late November to mid-March. It usually carries large amounts of dust, which it can transport hundreds of miles out over the Atlantic Ocean; the dust often interferes with local aircraft operations.

Description

During the winter or low sun period in the tropics, the Inter Tropical Convergence Zone (ITCZ) drops southward across northern Africa toward the Gulf of Guinea. A subtropical ridge of high pressure is over the central Sahara Desert. The Northeast Trade Winds to the north of the ITCZ also drop southward, now blowing across the Sahara Desert towards the countries that border the Gulf.