By Garrett Bushman 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 ID: 218588
Download Presentation The PPT/PDF document "avalanches" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
avalanches
By Garrett BushmanSlide2
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.Slide3
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.htmlSlide4
Conditions for Avalanches to Occur
Three variables interact to create unstable conditions for snow avalanches:
Steepness of slope
Stability of snowpack
Weather conditionsSlide5
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.Slide6
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.htmSlide7
Loose Snow Avalanches
Loose-snow avalanches typically start at a point and widen as they move
downslopeSlide8
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.Slide9
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.Slide10
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
.