What Is…Windchill?

Hmm…wind chill? What exactly is it? Let’s understand it just a little better.

Definition

Wind Chill is the term used to describe the rate of heat loss on the human body resulting from the combined effect of low air temperature and wind. As winds increase, heat is carried away from the body at a faster rate, driving down both the skin temperature and eventually the internal body temperature. While exposure to low wind chills can be life threatening to both humans and animals alike, the only effect that wind chill has on inanimate objects, such as vehicles, is that it shortens the time that it takes the object to cool to the actual air temperature (it cannot cool the object down below that air temperature).

Equations

Let’s get technical. For instance, if was 0 degrees outside with no wind, you’d lose X amount of body heat from exposed skin in a certain time period. Now, if it was -10 degrees outside with no wind, you’d lose Y amount of body heat from your skin in that same time period. So, at 0 degrees WITH wind, what wind speed makes you lose Y instead of X from your skin in the same time period?

By measuring the relationship between X and Y for given air temperatures (T), and wind speeds (V), we can create an equation for wind chill.

The latest equation as of 2001 is:
Wind Chill Equation
where T(wc) is the Wind Chill in degrees F, V is the Wind Speed in MPH, and T is the temperature in degrees F. This was likely calculated using a multivariate power regression model.

Results

Now, what does this equation tell us? Let’s visualize it! I’ve attached a pretty graphic I made in Excel using this equation (it’s prettier than the one I found online in the listed sources below). If any of you want to brush up on your Excel skills, I’ll happily share (see this link: Wind Chill).

This table below shows the calculated wind chill for a given wind speed (Y Axis) and outside temperature (X axis),

Wind Chill

As of Monday morning (1/4/2014) at 8am, Minneapolis, Minnesota shows a -28 air temp and a 22 mph gusting wind speed. That equates to a -60 degree wind chill! Be careful out there!

Advice

The best methods to protect yourself from frigid wind chills are to:

1) Limit exposed skin by wearing appropriate clothing

2) Wear layers and wind-resistant fabrics to keep body heat near the skin (instead of it being blown away). But don’t wear too tight of clothing such that circulation is reduced!

3) Stand in the sun! This can raise your temperature by as much as 10 degrees

4) If need be, raise your heart rate by quickening your pace to raise your internal body temperature

Sources:
http://mentalfloss.com/article/26730/how-wind-chill-calculated

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