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Flashcards in Avalanches Deck (16)
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1
Q

Two types of avalanches

A

Point release and slab

2
Q

slab avalanche

A

cohesive layers
triggered by people/victims
wind drifted snow or loading
they have a strongly packed top layer but a very thin and weak bottom layer.

3
Q

Point release avalanches

A

loose, cohesionless snow
entertainment from side walls as it rolls
dry snow makes it small
wet snow makes it large

4
Q

Dry avalanches

A

caused by too much stress
triggered by victims
loading of wind drifted snow or loading
fast

5
Q

wet avalanches

A

decreasing in strength
mostly natural
rain or prolonged melting
slower

6
Q

triggers for avalanches

A
snow accumulation over surface hoar
vehicles and humans increase the weight or 'normal force'
surface heating 
gravitational creep
shaking
7
Q

avalanche preconditions

A

loading through snow or wind packing
cornice
aspect to sun

8
Q

characteristics of northern/southern aspect to the sun

A

North is colder, south is sun facing and warmer

9
Q

characteristics of eastern/western aspect to the sun

A

West is warmer in the afternoon

East is warmer in the morning

10
Q

Surface Hoar formation

A

rapid deposition of water that goes into ice without wet phase, its formed on cold surface with humid air

11
Q

Tests for snow stability

A

copression test: Shoulder->elbow->wrist

cornice test

12
Q

Slope modifications/mitigation

A

snow umbrellas, snow fences and nets

13
Q

signs of avalanches

A
cracks in snow
snowfall
previous snow activity
temperature rising
strong winds
14
Q

Depth Hoar formation

A

depth hoar forms from temperature gradients between warm ground and cold snow surfaces.

15
Q

avalanche path is divided into which 3 parts

A

start zone
track
run-out zone

16
Q

Avalanches start at what angle

A

30-40