An avalanche is a high-velocity flow of snow down a mountainside. Avalanches are among the biggest dangers in the mountains for both life and property.
Many factors contribute to avalanches. Loose snow avalanches occur when the weight of the snowpack exceeds the shear strength within it, and are most common on steeper terrain. In fresh, loose snow the release is usually at a point and the avalanche then gradually widens down the slope as more snow is entrained, usually forming a teardrop appearance. This is in contrast to a slab avalanche. Slab avalanches account for around 90% of avalanche-related fatalities, and occur when there is a strong, stiff layer of snow known as a slab. These are usually formed when snow is deposited by the wind on a lee slope. When the slab fails, the fracture, in a weak layer, very rapidly propagates so that a large area, that can be hundreds of metres in extent and several metres thick, starts moving almost instantaneously. The third starting type is a slush avalanche which occurs when the snowpack becomes saturated by water. These tend to also start and spread out from a point.
As avalanches move down the slope they may entrain snow from the snowpack and grow in size. The snow may also mix with the air and form a powder cloud. An avalanche with a powder cloud is known as a powder snow avalanche. The powder cloud is a turbulent suspension of snow particles that flows as a gravity current. Powder snow avalanches are the largest avalanches and can exceed 300 km/h and 10,000,000 tonnes of snow, they can flow for long distance along flat valley bottoms and even up hill for short distances.
"Avalanche" is a song by Leonard Cohen. It appears on his third album, Songs of Love and Hate, released in 1971.
The lyrics are based on a poem he had previously written. The music is notoriously difficult to play on the guitar. Cohen went on record saying "Every guitarist has one chop, and I used mine on Avalanche". He acknowledged in a 1992 interview with Paul Zollo that his "chop", his unique pattern of playing, is behind many of his early songs.
Nick Cave & the Bad Seeds recorded a version of the song for their 1984 album From Her to Eternity.
