| What they are | Wind-carved ridges/grooves in snow |
| Caused by | Strong, persistent wind |
| Where | Exposed slopes, ridges, polar plains |
| Signal | Wind effect; possible wind slabs nearby |
From Russian, via the word for small ridges.
Sastrugi are sharp, irregular ridges and grooves carved into a snow surface by strong, persistent wind, common on exposed alpine slopes, ridgelines, and polar plains. Firm and uneven, they make for rough, jarring skiing and walking and signal significant wind effect on the snow surface — a clue to wind loading and possible wind slabs nearby.
Wind-sculpted snow
The surface sign of the same wind that builds a wind slab in the snowpack.
Frequently asked questions
What is sastrugi?
Sastrugi (also spelled zastrugi) are the sharp, wavy ridges and grooves that wind sculpts into a hardened snow surface. Strong, sustained wind erodes and redeposits snow into these irregular, often firm formations, which are common on exposed alpine terrain, ridgelines, and polar landscapes.
Why does sastrugi matter to skiers?
Sastrugi makes for rough, bumpy, jarring travel on skis or foot, since the firm ridges are uneven and unpredictable. Beyond the discomfort, its presence signals significant wind transport of snow, which is a clue that wind slabs may have formed on nearby leeward slopes — useful avalanche information.
How does sastrugi form?
It forms when strong wind erodes a snow surface in some places and deposits snow in others, carving the remaining harder snow into ridges aligned roughly with the wind direction. It requires firm, wind-affected snow and persistent wind, which is why it's typical of exposed, windy, and cold environments.
Sources
- Wind & snow surfaces — American Avalanche Association
- Snow features — The Mountaineers