A long river of dust blew through the Sahara Desert in late September 2022, extending more than 2,600 miles (4,180 km) from Libya to Mauritania. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired a true-color image of a portion of Saharan dust hanging over Mauritania and Western Sahara on September 21. The cloud of air-borne dust was so thick that much of the landscape beneath was obscured from view.
Sand seas provide ample material for dust storms, and such seas extend across substantial portions of Libya, Algeria, Mali, and Mauritania. Sand seas also cover parts of Western Sahara. In addition to sandy desert, this region is covered with impermanent rivers, and the fine sediments of dry riverbeds can also be borne aloft by winds.