April 8, 2011 - Saharan dust off Portugal

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A thick plume of dust hangs over the Atlantic Ocean off the coast of Portugal in this image from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA�s Terra satellite on April 6, 2011.

The dust blew in from the Sahara desert in North Africa, picked up by the strong winds associated with a low-pressure system. The low-pressure system channeled the dust west and then north, resulting in the plume off Portugal.

Airborne dust plays many roles in large-scale Earth processes. Dust is one of the most abundant aerosol particles in the atmosphere, and a natural seed for cloud formation. Dust particles and the clouds they generate can reflect energy from the Sun back into space, effectively shading Earth�s surface and cooling its temperature.

Dust also carries minerals, particularly iron, that help fertilize the Earth�s oceans. In iron-poor waters, dust provides essential nutrients for phytoplankton, tiny plants and plant-like organisms growing in the sunlit surface waters. In fact, a phytoplankton bloom colors the Atlantic beneath the dust in this image, although there is not necessarily a connection between the dust storm and this particular bloom.

Image Facts
Satellite: Terra
Date Acquired: 4/6/2011
Resolutions: 1km ( B), 500m ( B), 250m ( B)
Bands Used: 1,4,3
Image Credit: Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC