Landscapes and Water (GEOG 1011): Snow and Ice
Instuctor: Mark Williams
Please read the following powerpoint on avalanches.
You may want to print this out.
I'll make extensive use of this powerpoint
on Wednesday (17 November) and Friday (19 November).
Importance of Ice
Chapter 17, pages 519, 520
- About 77% of all the Earths freshwater is frozen.
- Most of that ice is in Greenland and Antarctica
- More than 29 million cubic kilometers (7 million cubic miles)
of water is tied up in ice.
- Worldwide glacial ice is in retreat appears to be in retreat
- 75% of the glaciers in the European Alps have receded in the past 50 years
- Cliffs and slopes above many high-elevation towns are held together
by permanently frozen conditions (permafrost).
- In the Alps in 2003, unprecedented warming caused some of this
permafrost to melt. The result was unprecedented deaths from
rockfall. Climbing routes on the Matterhorn and other peaks
were closed because guides realized the danger from rockfall
was both uncharacteristicly high and risk to bodily injury and
Importance of Snow
- 10% of the Earth's surface is covered by glacial ice,
with snow covering the glacial ice.
Almost all glacial ice starts as snow.
- Water resources. Snow melt runoff is the major source of water to
rivers and groundwaters over middle and high latitude areas.
- CA: 80% of all surface water is snowmelt.
- CO: 70% of all surface water is snowmelt.
- Climate. The single largest influence of global climate change
are changes in the amount of snow- and ice-covered area
- Earth's radiation balance is influenced by snow and ice
because of the high albedo of snow and ice relative to most
other land and sea surfaces.
- Small changes in climate can have very large
effects on precipitation as snow, the amount of
water stored as snow, and the timing and magnitude
of snowmelt runoff.
- Snow and ice melt add fresh water to the oceans,
changing the ocean's major currents
- Changes in the ocean's currents melt sea ice,
changing the global distribution of energy, changing
the location of the jet stream, with major changes
in regional and local climate.
- Recreation . Skiing, sledding, ice skating, snowshoeing
are just plain fun. Economic spinoff.
- Economics. The ski industry is the third largest
industry in Colorado.
- Transportation . Snow and avalanches are a major
constrain on highway travel. Think Donner Party.
- Biology . Snow insulates soils and vegetation from
cold winter air temperatures.
- Grain size
- Grain type
- Water Vapor
- Liquid Water
- Pore space
- "Ice skeleton"
Additional Snow notes
Some recent avalanche pics
Below are two recent pictures of avalanches
from near Silverton, CO, taken by Mark Rikkers.
Mark is a former CU-geography undergrad and graduate student
in snow hydrology who now is a profession avalanche
expert working for the Colorado Avalance Information Center.
He forecasts avalanche danger for the Red Mountain Pass/
Silverton/Ouray area and works with C-DOT on avalanche
control work on highway 555.
Cement Fill Avalanche