Dust Storm Off West Africa

Credit: Jeff Schmaltz; MODIS team; NASA, Posted on: Wednesday, 25 June 2008, 06:13 CDT Download full size image

On June 21, 2008, plumes of Saharan dust blew off the west coast of Africa, forming a large arc south and west of Cape Verde. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite took this picture the same day.

In this image, the diffuse dust plumes are thin enough to allow an easy view of the land and water below. Dust plumes near the coasts of Western Sahara and Mauritania are tan, while the dust blowing south of Cape Verde is lighter in color. The pale color near the upper left corner of the image is sunglint caused by sunlight reflecting off the ocean surface and into the satellite sensor. Near the upper right corner of this image, vortex streets—swirling clouds that occur in the wake of air-flow obstacles such as islands—form southwest of the Canary Islands. Although the Canary Islands appear to have escaped most of the dust from this storm, the island archipelago receives regular dustings from the Sahara.

Covering 8.6 million square kilometers (3.32 million square miles), the Sahara Desert fills nearly all of northern Africa. Sand plains and sand dunes cover roughly a quarter of the desert. Plumes blowing off the west coast of Africa frequently cross the Atlantic to the Caribbean where the dust has both beneficial and harmful effects. The dust often carries pathogens that harm Caribbean corals and exacerbate asthma symptoms among humans. Without regular doses of dust, however, Caribbean islands would have no soil to support plant life.

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