Wind Chill is the term used to describe the rate of heat loss on the human body resulting from the combined effect of low 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 temperature).
The wind chill index describes an equivalent temperature at which the heat loss from exposed flesh would be the same if the wind were near calm. For example, a wind chill index of -5 indicates that the affects of wind and temperature on exposed flesh are the same as if the air temperature were 5 degrees below zero even though the actual temperature is much higher.
The importance of the wind chill index is as an indicator of how to dress properly for winter weather. (Wind chill does not affect your car's antifreeze protection, freezing of water pipes, etc.) In dressing for cold weather an important factor to remember is that entrapped insulating air warmed by body heat is the best protection against the cold. Consequently, wear loose-fitting, lightweight, warm clothing in several layers. Outer garments should be tightly-woven, water-repellant and hooded. Mittens snug at the wrist are better protection than fingered gloves.
To use the chart, find the approximate temperature on the top of the chart. Read down until you are opposite the appropriate wind speed. The number which appears at the intersection of the temperature and wind speed is the wind chill index.
Wind Chill Index Wind
Temperature (° F) 35 30 25 20 15 10 5 0 -5 -10 -15 -20 -25 5 32 27 22 16 11 6 0 -5 -10 -15 -21 -26 -31 10 22 16 10 3 -3 -9 -15 -22 -27 -34 -40 -46 -52 15 16 9 2 -5 -11 -18 -25 -31 -38 -45 -51 -58 -65 20 12 4 -3 -10 -17 -24 -31 -39 -46 -53 -60 -67 -74 25 8 1 -7 -15 -22 -29 -36 -44 -51 -59 -66 -74 -81 30 6 -2 -10 -18 -25 -33 -41 -49 -56 -64 -71 -79 -86 35 4 -4 -12 -20 -27 -35 -43 -52 -58 -67 -74 -82 -92 40 3 -5 -13 -21 -29 -37 -45 -53 -60 -69 -76 -84 -92 Wind speeds above 40 mph have little additional chilling affect
Wind Chill Affects on Humans 32° F to -20° F Frostbite with prolonged exposure -20° F to -70° F Exposed flesh can freeze in one minute. < -70° F Exposed flesh can freeze in 30 seconds.
WIND CHILL FORMULA
To calculate the wind chill index for combinations of temperature and wind other than those given in the table above, you can use the formula: WC = 91.4 - (0.474677 - 0.020425 * V + 0.303107 * SQRT(V)) * (91.4 - T) where WC = wind chill index, V = wind speed (mph) and T = temperature (° F).
WIND CHILL CALCULATOR
WIND CHILL CONVERSIONS SPREADSHEET
COLD WEATHER HAZARDS
Frostbite is damage to body tissue caused by that tissue being frozen. Frostbite causes a loss of feeling and a white or pale appearance in extremities, such as fingers, toes, ear lobes, or the tip of the nose. If symptoms are detected, get medical help immediately! If you must wait for help, slowly rewarm affected areas. However, if the person is also showing signs of hypothermia, warm the body core before the extremities.
- Hypothermia (Low Body Temperature)
Warning signs - uncontrollable shivering, memory loss, disorientation, incoherence, slurred speech,drowsiness, and apparent exhaustion.
Detection - Take the person's temperature. If below 95F (35C),immediately seek medical care! If medical care is not available, begin warming the person slowly. Warm the body core first. If needed, use your own body heat to help. Get the person into dry clothing, and wrap them in a warm blanket covering the head and neck. Do not give the person alcohol, drugs, coffee, or any hot beverage or food; warm broth is better. Do not warm extremities (arms and legs) first! This drives the cold blood toward the heart and can lead to heart failure.
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