What is "Wind Chill"?
POSTED: Monday, December 16, 2013 - 10:03am
UPDATED: Wednesday, December 18, 2013 - 9:18am
Wind Chill Is Described As A "Feels-Like Temperature"
Monday, December 16th,2013 — The Borderland and the rest of the country have already seen 3 large Arctic Airmasses this season and winter does not even officially begin until this Saturday, December 21st at 10:11 MST. When a cold front pushes in most of the time it produces gusty winds. Theses winds make the cold air feel colder. The wind chill factor is in effect!
What is "Wind Chill"?
The wind chill temperature is how cold people and animals feel when outside. Wind chill is based on the rate of heat loss from exposed skin caused by wind and cold. When wind increases, it takes heat from the body, causing skin temperature to drop and eventually the internal body temperature. Therefore, the wind makes it FEEL much colder. Let’s say the air temperature is 0 degrees Fahrenheit and there is a 15-mph wind blowing. Using the chart this would create a wind chill of -19 degrees Fahrenheit, which can freeze exposed skin in 30 minutes!
Hypothermia occurs when body temperature falls below 95 degrees Fahrenheit. You need to seek medical attention immediately. I will describe what to do with someone with hypothermia in my next blog. I will tell you the best way to avoid “wind chilled” hypothermia is to wear a hat, because half of your body heat can be lost from your head. Cover your mouth to protect your lungs from extreme cold. Mittens, snug at the wrist, are better than gloves. Try to stay dry and out of the wind.
The National Weather Service in 2001 improved the Wind Chill Temperature (WCT) Index.
The new index uses modern science theories about heat transfer and is more accurate than the one developed in 1945. Here are some of the improvements:
-Calculates wind speed at an average height of five feet (typical height of an adult human face) based on readings from the national standard height of 33 feet (typical height of an anemometer)
-Is based on a human face model
-Incorporates modern heat transfer theory (heat loss from the body to its surroundings, during cold and breezy/windy days)
-Lowers the calm wind threshold to 3 mph
-Uses a consistent standard for skin tissue resistance
-Assumes no impact from the sun (i.e.., clear night sky).
The old wind chill formula was based on experiments conducted in Antarctica in 1945 in which scientists measured how long a can of water hanging on a pole chilled during different combinations of wind and temperature. The new formula uses "modern heat-transfer theory" instead of equations based on the 1945 experiments.
The new formula was tested this summer in a chilled wind tunnel at Canada's Defense Civil Institute of Environmental Medicine in Toronto. In the experiment, faces of several men and women were exposed to various temperatures and winds. The researchers measured how fast the temperatures of the exposed skin dropped to devise the new formula.
The new wind chills aren't nearly as scary sounding as the old ones. For example, at 5 degrees with a 30-mph wind, the old formula determined a wind chill of minus 40 degrees. The new formulas say the chill would be minus 19 degrees. The new formula was developing by representatives of seven agencies government, including the U.S.. National Weather Service, the Canadian weather service and university scientists.
Ultimately when a gusty cold front is carrying super chilly air, your best option is to stay indoors where it is dry and the “fells like temperature” is the actual warm, safe temperature.
Chuck DeBroder, Chief Meteorologist
KTSM, NewsChannel 9, NBC, El Paso, TX
www.twitter.com/ Chuck DeBroder NC9 @wxchuckNC9
(Photo: Chuck DeBroder-KTSM)