High winds swept dust and glacial sediments over the Gulf of Alaska on November 16, 2013. A semi-translucent plume of gray sediment pours from the Copper River Valley, located near the center of the image. To the east a narrower, lighter colored, but very dense plume rises near the terminus of the Bering Glacier.
The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured this true-color image at 2045 UTC (11:45 a.m. Anchorage Standard Time) on November 16. On that same day, the city of Cordova, located about 15 miles west of the Copper River Delta, recorded wind gusts as high as 34 mph (55 km/h).
Dust storms are most often thought of in association with sandy deserts, but such storms occur in many places. The slow movement of glaciers over time grinds rock into very fine sediment. Known as glacial silt, loess, or glacial flour, this sediment can easily be picked up by gusting wind, and may travel hundreds of kilometers. Glacial erosion has been so intense in this region that finely ground glacial silt has accumulated in large sand dunes in parts of the Copper River Valley, providing ready material for dust storms.