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Glossary of windbreak renovation terms Density � (windbreaks) � the ratio of solid area to total frontal area of a windbreak, expressed as a percentage. (Adapted from Brandle and Finch 1991)
Downwind � The direction that wind is blowing towards; wind blows from upwind to downwind.
End effect � Loss of snow storage near the end of a windbreak due to rounding and shortening of the ends of a snowdrift. Caused by generation of turbulent eddies at the end of a windbreak, increasing downwind of the windbreak.
Equilibrium � When a windbreak is at its full snow-storage capacity. Syn. capacity, saturation.
Fetch � Distance upwind of a windbreak that is contributing snow to the windbreak.
Girdling � The removal or killing of a ring of bark around the stem so that the flow of carbohydrates to roots is blocked. Ideally, this causes the roots to die and the whole tree is killed (Smith et al. 1997)
Laminar flow � The regular, continuous, nonturbulent movement in a specific direction, of the individual particles of a fluid such as air or water.
Live crown ratio � The percentage of length of stem containing living branches.
Pruning � The removal of branches from the main stem of a tree, or from larger branches.
Shelterbelt � See windbreak.
Storage capacity � The maximum amount of snow that a windbreak can capture and store.
Structure � (windbreaks) � The characteristics of a windbreak that determine its effectiveness in reducing windspeed and altering microclimate. Structure includes density, height of the tallest row, length, orientation, continuity, species and number of rows. (Adapted from Brandle and Finch 1991)
Thinning � Removal (cutting) of certain trees, with the goal of lowering the density of a stand of trees. This reduces the amount of competition for remaining trees.
Upwind � The direction the wind is coming from; wind blows from upwind to downwind.
Turbulent flow � The random motion of layers of a fluid, such as air or water, causing high resistance to movement through this fluid.
Windbreak � A barrier, usually consisting of rows of trees and shrubs, designed to reduce windspeed, modifying the microclimate in the sheltered zone behind the barrier. (Adapted from Brandle and Finch 1991) Syn. shelterbelt.
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