Saharan dust swept across Portugal and Spain in late March 2021, tinting skies orange and creating widespread haze. The Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Aqua satellite acquired a true-color image of the waning dust storm on March 31. On that day, haze hung over most of the Iberian Peninsula with a river-like plume of dust flowing northward across central Spain and spreading over the Bay of Biscay. The dust appeared to entrain with cloud over the North Atlantic Ocean. Dust also spread across France and was reported in the United Kingdom.
A system off the coast of Morocco began pushing dust from the Sahara Desert on March 26. Spain and Portugal were heavily covered on March 27 and March 28-30. By March 31 the sand and dust were sweeping north, leaving only a relatively small amount hanging over the Iberian Peninsula.
Each year more than 180 million tons of dust blow from the Sahara Desert of North Africa, lofted and transported by strong seasonal winds. Huge plumes travel westward across the tropical Atlantic Ocean towards South America each year, causing haze and carrying nutrients that fertilize the ocean and rainforests. While the cross-Atlantic route may be particularly dramatic, Saharan Dust often pours northward to cover Europe.