Avalanches

Loose Avalanche

• has a low moisture, snow slab has a thinner, weaker failure layer beneath it

• is also called "ground avalanche", happens because of rain, water percolation or water lubrication,

• it forms near the surface, has a triangular pattern on descent, are triggered by a local loss of cohesion because of sun or rain

• the flowing of snow is similar to the flowing of mud with high water content, typical of Northern Norway and Alaska

Which is NOT true?

• moisture content is low, density is near 100 kg/m3 or less, snow temperatures are less than 0 °C and snow depth is more than 1 m

• After the snow avalanche starts, a dust cloud which contains snow and air forms.

• dry avalanches have a dense core of snow at the bottom of the moving mass

• Powder avalanches often form by falling ice (or sometimes by ice avalanches) from steep icefalls, have less density than dry avalanches, their destructive power is more.

Tags

NGSS.MS-ESS3-2

Avalanches are always caused by an external stress on the snow pack

• True

• False

Wet Slab Snow Avalanche

• has a low moisture, snow slab has a thinner, weaker failure layer beneath it

• is also called "ground avalanche", happens because of rain, water percolation or water lubrication,

• it forms near the surface, has a triangular pattern on descent, are triggered by a local loss of cohesion because of sun or rain

• the flowing of snow is similar to the flowing of mud with high water content, typical of Northern Norway and Alaska

Tags

NGSS.MS-ESS3-2

Slopes flatter than 28 degrees or steeper than 55 degrees typically have a lower incidence of avalanche occurrence

• True

• False

Tags

NGSS.MS-ESS3-2

slopes with windward and sunny exposure have a lower incidence of avalanche hazard.

• True

• False

Tags

NGSS.MS-ESS3-2

Avalanches may appear on the same place few times per year or once in a few centuries

• True

• Flase

Tags

NGSS.MS-ESS3-2

skiers rarely trigger the rupture of the snow pack, already naturally instable

• True

• False

Natural triggers of avalanches include: (3 answers)

• precipitation

• radiative and convective heating

• rock fall and ice fall

• controlled explosive work

constantly trained snow pack observers do meteorological observations and in-situ observations to predict the possibility of avalanches

• True

• False

Tags

NGSS.MS-ESS3-2