Sastrugi

Sastrugi are elongated, sharp-edged ridges and troughs formed on a snow surface by wind action. They consist of wind-sculpted snow that has been eroded, transported, and redeposited by moving air, producing a corrugated texture commonly oriented parallel to the prevailing wind.

Formation and morphology: The process begins when wind picks up loose surface snow; grains are eroded by saltation and abrasion, then deposited as dense wind slabs in the lee of existing irregularities. The resulting ridges can take a range of shapes—from knife-like blades to rounded ridges—and typically run roughly along the wind direction. Heights range from a few centimeters to about a meter; spacing from several centimeters to meters.

Distribution and environment: Sastrugi are a characteristic feature of snowfields in polar regions and high winds. They form on dry, fresh snow as well as on older snowpacks, and are especially common on sea ice in the Arctic and Antarctic, where persistent wind regimes sculpt the surface. They can form quickly after snowfall events and may persist for days to weeks, subject to wind remobilization and metamorphism of the snow crystals.

Implications and significance: The irregular surface created by sastrugi can hinder overland travel, skiing, and snow measurements. They influence surface roughness, affect albedo and local thermal properties, and can complicate the interpretation of snow- and ice-field data collected in field studies.