Blowing in the Wind

It is quite intuitive to think that things that are lighter will be more prone to be wind blown than heavier objects.  Items less likely to be blown about if they are heavy, such as a large metal object, or that have a high moisture content like food waste, or  that have been compacted as in a compactor truck. 

We also have to think about surface area as well.  For example, a flat sheet of paper has a great surface area that easily becomes wind blown, yet if it is crumpled into a ball, it has a lower surface area and is less easily wind blown.   We are all aware of the problem with plastic bags being blown about.  Plastic bags are not only light and have a large surface area, but wind will blow into an open bag and carry them aloft.  

Studies carried out in the late 70's for the Crowsnest Pincher Creek Regional Landfill showed how far a variety of objects could be blown at different wind speeds.  The study was based on an object dropping about 1.5 M (as it would from an unloading collection vehicle), and that it would be blown away from the working face of the landfill.  

Wind Speed                    Objects

10 - 25 km/hr                    Envelopes, dry paper

25 - 30 km/hr                    Empty plastic bags

30 - 50 km/hr                    Corrugated cardboard sheets, crumpled paper towels

50 - 60 km/hr                    Plastic strips, empty tissue boxes, tightly crumpled paper

60 - 90 km/hr                    Milk cartons, cardboard boxes

over 90 km/hr                   Metal cans

The energy in the wind is cubically proportional to the wind speedThe strength of the wind should never be under estimated.  (E = v3).  If wind speed is doubled, the energy increases by 8 times (2 x 2 x 2 = 8).  Never under estimate the power in the wind.  In strong winds, large objects, as shown here, can be blown out of the active landfill working face.