|MadSci Network: Earth Sciences
Snow fences are intended for several purposes. All of these rely on the fact that snow fences cause snow to drift down wind of them thus either collecting water in a place it is wanted or preventing snow from piling where it is not wanted. They are used in many places and interestingly they are also used on the sea shore to cause dunes to form where they are wanted or to control the progress of sand into areas where it is not wanted. So when you go to the seacoast you will see the same thing.
How they work is quite simple. Whenever the wind goes over a fence or wall it forms an eddy current behind the wall. This is a rolling wind current that flows downward and back to the back side of the fence. Thus it causes fast and slow places to develop in the wind. It makes a drift form in front of the fence on the windward side.
(Good Picture and Info)
(a Company with a checklist for how to install the fences) http://www.ida.net:80/users/perma/pinstall.htm http://www.ida.net:80/users/perma/index.html
This empties the air of snow before it crosses the road. It also causes fast air to form, as it is drawn downward, a little farther away so that it blows the snow away from that area. All of these devices rely on the fact that the wind that deposits the material you want to control is nearly always coming from the same direction. In the Colorado area the winter snows blow mostly from one direction. On the beach the prevailing winds are mostly from one direction too. So the builder of the fence can plan their effects by merely placing the fence. Wind erosion Site: http://www.waite.adelaide.edu.au:80/Soil_Science/wwind.html
So actually they donít stop the snow from blowing across the road, they pile it along side and like a leaf blower they blow any snow off the road. Hopefully this helps you understand the function of a snow fence. This is quite similar to the building of groins or jetties along the sea coast to control the deposition of sand on beaches and harbors. Check this US Army site for information on Beaches waterways and harbors. http://www.wes.army.mil/
Harvest, Al USA
Try the links in the MadSci Library for more information on Earth Sciences.