Depth hoar

Schwimmschnee

Depth hoar is a type of snow crystal that forms within the snowpack. It is characterized by its large, faceted crystals that develop due to temperature gradients within the snow. Depth hoar is known for its weak bonding, which can lead to avalanche conditions.

Formation

Depth hoar forms when there is a significant temperature gradient within the snowpack. This typically occurs when the ground is warmer than the surface of the snow. Water vapor moves from the warmer ground to the colder surface, causing the snow crystals to sublimate and then re-deposit as larger, faceted crystals. This process is known as temperature gradient metamorphism.

Characteristics

Depth hoar crystals are usually large and have a faceted structure. They are often found at the base of the snowpack and can be several millimeters in size. The weak bonding between depth hoar crystals makes them a significant factor in the stability of the snowpack. When a layer of depth hoar is present, it can act as a weak layer, increasing the risk of avalanches.

Impact on Snow Stability

The presence of depth hoar in the snowpack is a critical factor in avalanche forecasting. Because depth hoar layers are weak, they can easily collapse under the weight of additional snow or the pressure of a skier or snowboarder. This collapse can trigger a slab avalanche, where a cohesive layer of snow slides down the slope.

Related Snow Types

• Surface hoar
• Graupel
• Firn
• Corn snow

See Also

• Avalanche
• Snowpack
• Snow metamorphism
• Snow science