Avalanche and Its Safety
An avalanche
is a sudden and rapid flow of snow, often mixed with air and water, down a
mountainside. Avalanches are (51) 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 (52) supports it. Determining the
critical load, the amount of over-burden which is (53) to
cause an avalanche, (54) 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 (55)
of avalanche. Snow does not (56) significantly on
steep slopes; also, snow does not (57) easily on flat slopes.
Human-triggered avalanches have the greatest incidence when the snow’s angle of
rest is (58) 35 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 (59) 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 (60) ;
that is, the more a slope is disturbed by skiers, the more likely it is that an
avalanche will occur.
Duc to the complexity of the subject,
winter travelling in the backcountry is never 100% safe. Good avalanche safety
is a continuous (61) , including route selection and
examination of the snowpack, weather (62) , and human
factors. Several well-known good habits can also (63) the
risk. If local authorities issue avalanche risk reports, they should be
considered and all warnings should be paid (64) 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 (65) or
damaged. Avoid traveling below others who might trigger an
avalanche. |
