Sastrugi, or zastrugi, are features formed by erosion of snow by wind.
They are found in polar regions, and in snowy, wind-swept areas of temperate regions, such as frozen lakes or mountain ridges.
Sastrugi are distinguished by upwind-facing points, resembling anvils, which move downwind as the surface erodes.
These points usually lie along ridges parallel to the prevailing wind; they are steep on the windward side and sloping to the leeward side. Smaller irregularities of this type are known as ripples or wind ridges.
Wind sculpted snow near South Pole Station, forming sastrugi features.
Large sastrugi seen in radar image around the south edge (left side) of Lake Vostok in Antarctica (RADARSAT, NASA). White and black colors on sastrugi are not lights and shadows, they demonstrate difference in radioreflectivity of snow deposits on the windward and leeward sides of a sastruga.
A barchan or barkhan dune is a crescent-shaped dune. The term was introduced in 1881 by Russian naturalist Alexander von Middendorf, based on their occurrence in Turkestan and other inland desert regions. Barchans face the wind, appearing convex and are produced by wind action predominantly from one direction. They are a very common landform in sandy deserts all over the world and are arc-shaped, markedly asymmetrical in cross section, with a gentle slope facing toward the wind sand ridge, comprising well-sorted sand.
Typical shape
Barchan in the Namib Desert
Image: Barchan
