Sastrugi, or zastrugi are sharp irregular grooves or ridges formed on a snow surface by wind erosion and deposition, and found in polar and temperate snow regions. They differ from sand dunes in that the ridges are markedly parallel to the prevailing winds.
Sastrugi are various surface irregularities resulting from wind erosion, saltation of snow particles and deposition. Smaller irregularities or this type are known as ripples (small, ~10 mm high), or wind ridges.
Larger features are especially troublesome to skiers and snowboarders. Traveling on the irregular surface of sastrugi can be very tiring, and can risk breaking equipment—ripples and waves are often undercut, the surface is hard and unforgiving with constant minor topographic changes between ridge and trough.
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The words sastrugi/zastrugi are Russian-language plurals: the singular is sastruga or zastruga. The form "Sastruga" is the German-language transliteration of the Russian word Russian: Заструга. [1]
A Latin-type analogical singular sastrugus is used in various writings including Robert Falcon Scott's expedition's diaries, and Ernest Shackleton's The Heart of the Antarctic.
Under the wind, free snow particles accumulate and drift in a way similar to barchan dunes of sand. For this reason, the resulting drifting snow shapes are also popularly referred to as "barchans", while Inuit of Canada call them kalutoqaniq. When winds slacken, barchans"/kalutoqaniq consolidate via sublimation and recrystallization. Subsequent winds erode kalutoqaniq into sculptured forms of zastrugi. Inuit call large sculptirings kaioqlaq and the small ripples tumarinyiq. Further erosion may turn kaioqlaq back into a drifting kalutoqaniq. An intermediate stage of erosion is mapsuk, an overhanging shape. At the windward end of a ridge, the base erodes faster than above, producing a recognizable shape of anvil tip pointing upwind. [2]