On February 10, 2014 the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite flew over Alaska and captured a true-color image of several dust storms blowing off the coast. In this image, dust appears as pale gray plumes blowing southwest from the brightly reflective snowy coastline over the deep blue water of the Gulf of Alaska. A bank of white clouds covers the southwestern corner of the image.
Unlike the more common image of desert dust-storms, which are made up of sand, dust storms originating in this section of Alaska are made up of glacial sediments. The slow, steady movement of glaciers over rock and soil acts like a crushing weight, grinding the stone beneath to fine silt. Also called loess, this glacial silt can easily become lifted aloft. In some areas the glacial erosion has been so effective and persistent that the silt forms dunes, especially in river valleys.