On July 19, 2013 the Moderate Resolution Imaging Spectroradiometer (MODIS) flying aboard NASA’s Terra satellite passed over the western coast of Africa and captured a massive dust storm in progress.
A broad, swirling river of dust pours over Mauritania, Senegal, and The Gambia (from north to south in the image), and flows westward over the Atlantic Ocean. The dust is so thick that three of the eastern Cape Verde Islands (Boa Vista, Maio, and Santiago) are nearly obscured from view. Western Sahara, which can be seen in the far north of the mainland, appears relatively dust free.
Mauritania’s sandy and rocky landscape, which includes a part of the Sahara Desert, is a prime source for massive dust storms. About three-fourths of Mauritania is desert or semi-desert, and this sandy surface has been expanding since the 1960s. Strong winds are common in this arid and relatively flat landscape, and dust hoisted aloft can be carried vast distances by the prevailing winds. Saharan dust periodically crosses the Atlantic Ocean, reaching both North and South America, especially during the Northern Hemisphere’s summer season.