1. By Garrett Bushman avalanches

2. I chose avalanches for my eportfolio because I love to ski. Being that I ski so much and that I especially like to ski the backcountry its important that I am aware of avalanche danger.

3. What is an Avalanche? • A snow avalanche is the rapid downslope movement of snow and ice, sometimes with the addition of rock, soil and vegetation. • http://www.uvm.edu/~inquiryb/webquest/sp08/pmontgom/avalanchesandmudslies.html

4. Conditions for Avalanches to Occur • Three variables interact to create unstable conditions for snow avalanches: • Steepness of slope • Stability of snowpack • Weather conditions

5. Steepness of Slope • The steepest angle at which snow, or any loose material, is stable is its angle of repose. For snow, this angle is affected by temperature, wetness, and shape of the snow grains. • Most snow avalanches occur on slopes between 35 and 40 degrees.

6. Stability of Snowpack & Weather • Snow covered slopes may become unstable when the wind piles up snow on the leeward or downwind side of a ridge or hillcrest, when rapid precipitation adds weight to the slope, or when temperatures rapidly warm to make snow very wet. • http://science.howstuffworks.com/nature/natural-disasters/avalanche4.htm

7. Loose Snow Avalanches • Loose-snow avalanches typically start at a point and widen as they move downslope

8. This is a picture of me skiing at Alta Ski Resort in Little Cottonwood Canyon. As a skier I have to pay particular attention to snow conditions. On a day like this where it was snowing really hard, skiing in the backcountry wouldn’t be a good idea because of the amount of new snow on top of old hard snow. With this new add of weight it could make the snow unstable and cause an avalanche. It is important to wait until ski patrol has bombed the hazardous areas and they have cleared it safe for skiing.

9. THE END • In closing, its important to know the conditions you are in as a skier to be the safest. Always pay attention to the weather, but in the end just have fun and don’t be stupid.

10. Slab Avalanches • Slab avalanches start as cohesive blocks of snow and ice that move down-slope. These are the most dangerous types of avalanches and are usually triggered by the overloading of a slope or the development of zones of weakness in the snowpack. Millions of tons of snow and ice then move rapidly downslope at velocities of up to 60 miles per hour.