What is Wind Chill?

Nebraska Extension Master Gardeners are individuals who are passionate about gardening and sharing research-proven solutions.  Potential volunteers apply and go through an interview to be selected as an intern.  They will receive over 48 hours of initial education from experts in soils, botany, landscape design and more and give back 40 hours of volunteer service to their counties annually.  Over 200 active Extension Master Gardeners in Douglas-Sarpy counties donate over 14,000 hours of their time yearly.

This week we asked our Master Gardener volunteers to write blogs for GRO Big Red and these are their articles.  Many thanks to the Master Gardeners for their willingness to learn and give back.

If you are curious about the program or would like to know more, join us November 14th at 6:30 pm at 8015 W. Center Road in Omaha or November 16th at 1:00 pm at Sump Memorial Library in Papillion to learn more about the Extension Master Gardener program in Douglas-Sarpy counties.

–Scott, Kathleen, John, Jonathan, John

Wind chill chart from Scott Risch

What is Wind Chill?

By Master Gardener Scott Risch

As we transition into winter, we’ll start hearing wind chill mentioned in our forecasts.  My Dad use to say that wind chill and the heat index used during summer simply makes us feel worse!  So, what exactly is wind chill?

The first wind chill experiments were conducted in Antarctica in 1945.  Two explorers, Paul Siple and Charles Passel measured how wind speed affects the rate of heat loss.  They filled a plastic container with water, hung it from a pole and measured how quickly the water lost heat (or in this case, how quickly the water turned to ice).  Their experiment showed that the faster the wind was blowing, the faster the water turned to ice.  For we humans, that means the windier it is, the more heat we lose faster thus making us feel colder.  Later experiments involved volunteers walking on a treadmill in a cold wind tunnel with sensors on the outside of their faces.  This later experiment led to a revision of the wind chill charts in 2001.  The new chart provides slightly warmer values.

Wind chill is only valid for objects that are warmer than the ambient air, for example our body, warm-blooded animals and even combustion engines.  Plants basically respond to the actual (air or ambient) temperature and therefore, can’t feel colder.  When determining to protect or bring in your plants on a cold night, consider the actual temperature.  If the temperature will be 38 degrees F with a wind chill of 32, make your decision on the 38 degrees F rather than the wind chill of 32 degrees F.

Wind chill does, however, affect plants because the wind has a drying effect and can cause damage during colder temperatures by drying out plant tissues, particularly leaves.  Make sure to water the root area of plants prior to a freeze and make sure the roots do not dry out excessively during extended periods of freezing temperatures to minimize this drying effect.  The root area should not be soggy wet but evenly moist.  Periodic watering of unfrozen soil during the winter months for evergreens can offset the drying out effect of cold, dry winter winds.

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