Landscapes and Water (GEOG 1011): Snow and Ice

Instuctor: Mark Williams
Telephone: 492-8830

INTRO

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).
Avalanche Powerpoint

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 death unacceptable.

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.

Snow Properties

• Temperature
• Density
• Grain size
• Grain type
• Hardness
• Stratigraphy
• Thermal

Mountain Snowpack

• Ice
• Water Vapor
• Liquid Water
• Pore space
• Contaminants
• "Ice skeleton"

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
Eagle Avalanche