English: Strong winds frequently loft dust and sand from the Sahara Desert then carry it across western African and over the Atlantic Ocean. On June 6, 2019, the Moderate Resolution Spectroradiometer (MODIS) on NASA’s Terra satellite caught a glimpse of a wide blanket of dust covering the Cape Verde Islands, which lie about 400 miles (650 km) off the coast of Senegal.

Note the wind shadows, wakes, and vortices—areas with less dust density—on the leeward side of the islands. Winds blowing from the northeast and east run into the high volcanic peaks of the islands, which block some of the dust and alter the air flow behind the islands. The flow of the air can be seen in patterns created by both tan dust and white cloud.

Hundreds of millions of tons of dust blow out of Africa every year, crossing the Atlantic all the way to the Caribbean and the Gulf of Mexico. This dust fertilizes the ocean with nutrients that can promote plankton growth, but it can also carry fungus and disease-causing microorganisms that damage coral reefs.