Snowdrift

A snowdrift is a deposit of snow sculpted by wind into a mound during a snowstorm, formed by a process comparable to the way wind builds sand dunes. Wind carries light snow across a surface and drops it once the airflow slows, typically where a stationary obstacle interrupts the wind; the resulting drift usually crests and slopes down on the side facing the wind, while the sheltered side stays lower and relatively flat. Snowdrifts commonly build up on roads, where the road surface or its furrows disturb the wind enough to cause snow to settle, which is why snow fences are sometimes placed upwind of roads to intercept drifting snow before it reaches the roadway.