On July 14, 2021, the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite captured a true-color image of a vast train of dust moving Africa to Europe. Dust stretched from Chad and Niger (far south of the lower edge of the image) and over the Mediterranean Sea to reach northern Poland—a distance of about 4,400 km (2,700 miles).
Tens of millions of tons of dust blow out each year from northern and western Africa, lofted from the Sahara Desert by strong seasonal winds. Dust storms can degrade air quality, but they also play an important role in absorbing and reflecting solar energy to regulate Earth’s climate. Dust also fertilizes ocean and land ecosystems with iron and various minerals that help plants and phytoplankton grow.