Chapter 7: Snow Avalanches
avalanche cord
a 10m rope that drags behind a person while skiing, snowboarding, or snowshoeing
slab avalanche
a large-scale avalanche formed when a slab of ice and snow breaks away from the main ice pack
avalanche transceiver
a portable device that emits a radio signal to assist in finding the location of a victim
track
along which the avalanche accelerates and achieves its highest velocity
run-out zone
avalanche slows down and deposits snow
point-release avalanches
begin with failure of a small amount of loose fluffy snow, widens as it moves downslope and commonly happen after a heavy snowfall
hoar
consists of ice crystals that are deposited on and within the snowpack when the air is moist and cold
berms
deflect avalanches away from buildings or parallel to roads
hoar frost
frost made from small ice crystals
30-45 degrees
most large avalanches are released from slopes at what angle?
sluff - small snow slide that does not bury a person; small - avalanche stops on the slope; medium - avalanche runs to the bottom of the slope; large - avalanche runs out over areas significantly less steep that 30 degrees, may reach the valley bottom and run up the lower part of the opposing slope
name the 4 sizes of avalanches and their run out
occurrences of avalanches, stability and strength tests, snowpack observations, weather
name the four types of information avalanches are based on
start zone, track, run-out zone
name the three parts of an avalanche's path
start zone
the area where the snowpack first fails
slope steepness
the most important terrain factor for avalanche formation is?
a buried weak layer and an overlying stronger slab
what do slab avalanches require?
annual mean snow depth
what does AMSD stand for?
wind slab
a body of thick, poorly bonded snow deposited by wind
snow avalanche
a rapid downslope movement of snow and ice, sometimes with the addition of rock, soil, and trees.