Avalanches happen, and they are terrifying. If you’re new to the backcountry, the amount of knowledge, classes, gadgets, and gear to wade through – never mind the horror stories – can be intimidating. Avalanches should be intimidating, but learning about them should not. Here is some basic avalanche terminology to familiarize yourself with as you delve into the world of snow science.
The Aspect, or slope orientation, refers to the compass direction of a particular slope, taken perpendicular to the fall line. Solar radiation, wind loading, and other weather factors (all crucial in snowpack and its stability) vary with aspect.
Cornices are overhanging lips of snow that form from wind drift on top of a ridge. Cornices can be extremely dangerous on many levels. They can collapse suddenly, sending the skier tumbling onto the slope below, or burying a skier beneath its weight. A cornice fall can also trigger destructive avalanches. Stay clear of traveling below cornices on warm, sunny days or days with warming rain.
Crown, or fracture line, refers to the wall of snow left behind where an avalanche slab sheared off.
Faceted snow refers to ‘sugary’ textured snow. The individual snow grains are angular and have less cohesion between them. These grains are called facets, and the process by which they form, usually in shallow snowpack in consistently cold air temperatures, is called faceting. This type of snow creates weak, porous, unstable layers.
When a deep, compact snowpack is exposed to warm air for an extended period of time, the snow grains become small and rounded. These grains are called rounds, and the process of rounding creates a hard, strong layer of snow.
Terrain traps refers to any feature in the landscape, such as cliffs, bodies of water, exposed trees, rocks, and crevasses, that would elevate the consequence of being caught.
Surface Hoar is sometimes called ‘winter’s dew.’ It’s a layer of feathery crystals that result from cold, clear nights with little wind, often big enough to be seen by the naked eye. It’s beautiful, but watch out! Buried surface hoar is a persistant weak layer and becomes the failure layer for many avalanches.
That’s right, it’s a technical term! Whumph refers to the sound of snowpack collapsing as you travel across it. If you hear this, take heed, the snowpack is very unstable!