How Strong is the Wind

Wind	Km/Hr	Wind Blown Litter
Calm	Up to 10	light film and paper
Light	10 -  20	crumpled dry paper, empty plastic bags
Moderate	20 - 40	light weight empty boxes, flat cardboard, paper products
Strong	40 - 60	corrugated cardboard boxes, sheets of Styrofoam, plastic containers
Gale	60 - 90	large boxes, sheets of ridge plastic, carpet, brush
Storm	90 - 117	construction materials (e.g. plywood sheets)
Hurricane	over 118	almost anything that is not secured
Tornado (F1 - F5)	105 - 322	dangerous winds

This table was derived from a litter study project for the Lethbridge Regional Landfill (Salbro Consulting).  Much of the information was adopted from a litter study that was done for the Pincher Creek Regional Landfill in the late 1970's.  The concept is that if was was dropped in these wind conditions, what litter would be carried by the wind away from the working face.   In the original Pincher Creek study, various materials were dropped from a 1.5 meter height in various wind speeds to observe what is carried in these winds. 

This reasoning was based on the idea that when waste is unloaded from customer vehicles at the working face, it is the point where the waste is most exposed to the wind.   

You may find in actual wind conditions that materials not identified in this table are carried by the wind and that some materials may not necessarily be carried by the wind, but may drift along the ground surface.  This table can be used as a general guide for different wind conditions, but shouldn't be thought of as a definitive description of what litter will blow in different winds.  

One thing that is clear though, "the stronger the wind,  the bigger the objects that will be blown by the wind".  

Also, keep in mind that two other factors that will have an influence on wind blown litter are turbulence and wind direction.  

Jim