An avalanche is a sudden and rapid flow of snow, often mixed with air and
water, down a mountainside. Avalanches are {{U}} {{U}} 1
{{/U}} {{/U}}the biggest dangers in the mountains for both life and
property. All avalanches are caused by an over-burden of
material, typically snowpack, that is too massive and unstable for the slope
{{U}} {{U}} 2 {{/U}} {{/U}}supports it. Determining the critical
load, the amount of over-burden which is {{U}} {{U}} 3 {{/U}}
{{/U}}to cause an avalanche, {{U}} {{U}} 4 {{/U}} {{/U}}a complex
task involving the evaluation of a number of factors. Terrain
slopes flatter than 25 degrees or steeper than 60 degrees typically have a low
{{U}} {{U}} 5 {{/U}} {{/U}}of avalanche. Snow does not {{U}}
{{U}} 6 {{/U}} {{/U}}significantly on steep slopes; also, snow does
not {{U}} {{U}} 7 {{/U}} {{/U}}easily on flat slopes.
Human-triggered avalanches have the greatest incidence when the snow's angle of
rest is {{U}} {{U}} 8 {{/U}} {{/U}}35 degrees and 45 degrees;
the critical angle, the angle at which the human incidence of avalanches is
greatest, is 38 degrees. The rule of thumb is. A slope that is {{U}}
{{U}} 9 {{/U}} {{/U}}enough to hold snow but steep enough to ski has
the potential to generate an avalanche, regardless of the angle. Additionally,
avalanche risk increases with {{U}} {{U}} 10 {{/U}} {{/U}}that
is, the more a slope is disturbed by skiers, the more likely it is that an
avalanche will occur. Due to the complexity of the subject,
winter travelling in the backcountry is never 100% safe. Good avalanche safety
is a continuous {{U}} {{U}} 11 {{/U}} {{/U}}, including route
selection and examination of the snowpack, weather {{U}} {{U}} 12
{{/U}} {{/U}}, and human factors. Several well-known good habits can also
{{U}} {{U}} 13 {{/U}} {{/U}}the risk. If local authorities issue
avalanche risk reports, they should be considered and all warnings should be
paid {{U}} {{U}} 14 {{/U}} {{/U}}to. Never follow in the tracks
of others without your own evaluations; snow conditions are almost certain to
have changed since they were made. Observe the terrain and note obvious
avalanche paths where plants are {{U}} {{U}} 15 {{/U}} {{/U}}or
damaged. Avoid traveling below others who might trigger an avalanche.