Avalanches are
caused by
a layer of snow known as a depth hoar, a
very dangerous snow condition,
which is also known as sugar snow. It is made of large, round and
cup-shaped snow crystal that act like ball bearings, causing any snow on top to slide
right off. It would be like trying to walk across a floor covered with
marbles. The smallest movement, from a person or an animal, can
cause an avalanche.
The shapes of the
snowflakes determines how stable the snow cover is. Snow that
is stable and solidly packed does not slide easily and usually doesn’t
cause avalanches. Crystals make the most stable snow because the six
points of each flake interlocks with other crystals. When both
granules and pellets fall from the sky, they roll over each other,
making snow loose and unstable. Granules and pellets are most likely to cause an
avalanche because they consist of different kinds of flakes or
different layers of snow. A layer of loose snow can slide over another layer
or more solid snow.
This are two types of
avalanches, dry slab avalanche and wet slab avalanche. Snow doesn’t
like rapid
change. Dry slab avalanches happen when the weak layer beneath the
slab fractures, usually cause by too much weight has been added too
quickly, which overloads the buried weak layer. The speed of dry slab
avalanches vary from 60-80 miles per hour. They reach these speeds in
about 5 seconds after they fracture. Wet slab avalanches occur when
percolating water dissolves the bonds between the snow grains, which
decrease the strength of the buried weak layer. Wet avalanches run
slower about 20 miles per hour.
Avalanches are
caused
t
is stable and solidly packed does not slide easily and usually doesn’t
cause avalanches. Crystals make the most stable snow because the six
points of each flake interlocks with other crystals. When both
granules and pellets fall from the sky, they roll over each other,
making snow loose and unstable. Granules and pellets are most likely to cause an
avalanche because they consist of different kinds of flakes or
different layers of snow. A layer of loose snow can slide over another layer
or more solid snow.