7 January 2015
With wind chills almost certainly reaching -30 or lower across the Eastern U.S. tonight, I thought you might be interested in some information about what it does and does not measure.
First of all, water will not freeze at 33 degrees, no matter how hard the wind blows, and the wind chill is NOT “how cold it feels”. What it does measure is the rate of heat loss due to cold and wind. The lower the wind chill the faster you will lose heat on your skin, and the quicker the water the temperature in your pool will drop. By the way, the wind chill formula we use today is a revised from the one that was used in the 1960′s through 1980′s, after new research showed some errors in the old formula. You can read more about wind chill on this very good wiki page here.
We often get requests for the formula for wind chill and if algebra scares you then it’s not as simple as you might think. Here it is:
Wind chill temperature = 35.74 + 0.6215T – 35.75V (**0.16) + 0.4275TV(**0.16)
T is temp in degrees F and V is wind speed in mph. This is actually the APPROXIMATE formula! Trust me, it is easier to use the wind chill chart at the top of this post.
One last bit of advice from someone who spent a little time at the South Pole when the wind chill was -65. Do NOT wear tight clothes when it’s cold. Yes, wear layers, but make them loose and bulky. Air is a great insulator, and one pair of thick but loose socks in an oversize shoe will keep your feet much warmer than 3 pairs in a tight shoe! Cover everything you can and wear a good hat and mittens instead of gloves.