Sastrugi

Sastrugi, also called zastrugi, are wind-eroded snow features found in polar regions and in windswept snowy parts of temperate regions, such as frozen lakes or mountain ridges. They form when wind-driven snow first accumulates in dune-like mounds and, once the wind eases, consolidates through sublimation and recrystallization; renewed wind then carves the consolidated snow into ridges with a steep, anvil-like point facing upwind and a gentler slope facing downwind, because the base of the ridge erodes faster than its top. These ridges generally align parallel to the prevailing wind and can shift back and forth between drifted mounds and sculpted ridges as wind conditions change.