Hobbies And Interests
Snow
An avalanche is made of snow, but not all snow is created equal. Snow can be very moist and heavy or dry and light. After snow hits the ground and accumulates, its structure continues to change. Air temperature, ground temperature, humidity and wind all combine to modify the layers of snow. Sometimes the top layer will become very glassy and slick, and when a heavy storm dumps a lot of snow on top, the avalanche risk intensifies. In other cases, a layer near the bottom of the snow pack loses its cohesion, allowing the surface snow to slide away.
Trigger
Avalanches don't happen for no reason at all. They require some triggering event. Often, skiers and snowmobilers provide just enough energy to the slope to get the snow moving downhill. In the Rocky Mountains, teams of state workers fire mortar shells into mountain slopes to release built-up snow. Apart from people, natural factors can also trigger an avalanche. Rain and warmer temperatures are often the cause of springtime avalanches. Sudden, heavy snow is also a frequent trigger.
Speed and Power
A large avalanche can reach speeds of 80 miles per hour or more and weigh many tons. Trees and structures stand little chance against the force of all that moving snow. In 1910, an avalanche killed nearly 100 people in the Cascade Mountains of Washington when it overwhelmed two stationary trains. Avalanches made of wet snow that falls away from the mountain in slabs are the most powerful and dangerous variety.
Aftermath
When the avalanche descends to an area with a more gradual slope, it slows down and eventually stops. As soon as the snow and debris come to a halt, the whole mass becomes extremely dense. A skier trapped in the snow cannot simply dig himself out. The keys to survival are clearing out enough space to breathe and wearing a locator device.