![]() ![]() This has ramifications, say in cases when one might be concerned about pipes freezing in cold weather episodes. Does the bowl of water freeze? The answer is no, the bowl of water does not freeze because it's only impacted by the absolute temperature, which in this example is above freezing (32 degrees Fahrenheit.) The wind chill temperature of 28 degrees Fahrenheit has no impact on the water because the water is not a living thing. Say you have a bowl of water outside in an environment where the air temperature is 35 degrees Fahrenheit and the wind chill is 28 degrees Fahrenheit. For cold weather impacts on non-living things absolute temperature is used to gauge the effect. The wind chill does impact inanimate objects like your car, or house, pipes or landscaping. Still, the approximate cooling effect on a windy, cold, but sunny day can be used with confidence in how to dress to protect against hypothermia and frost bite.īecause wind chill is not the same as temperature and is a value that expresses how quickly exposed skin surfaces will cool in cold windy conditions, it only impacts living things. Therefore a wind chill calculation will imply a more significant cooling impact than what is true during the day, when the sun is out. ![]() This is an important point for daytime use of wind chill if the sun is out as the impact of the sun is significant in reducing the cooling effect of the wind on the body. In other words, the wind chill calculation is most accurate and valid on a clear night. 6) The index assumes no effect from the sun. 4) The index uses a consistent standard for skin tissue resistance 5) Wind chill is only valid and defined for air temperatures of 50 degrees Fahrenheit or lower. In other words, wind chill is calculated using wind speed values greater than 3 mph. 3) The index assumes a measured wind of 3 mph or less is calm. 2) The index is based on a human face model and incorporates heat transfer theory based on heat loss from the body into the surrounding air on cold windy days. The wind speed calculation is done using measured wind speed data which is recorded at the standard anemometer observation height of thirty three feet. This is the wind chill equation used to calculate what meteorologists term a "Real Feel" temperature which helps to approximate how quickly exposed skin will cool in cold windy air.įrom the National Weather Service definition, which you can view by clicking here, this is what the wind chill index does: 1) The index calculates wind speed at approximately five feet, which is a fairly typical height of the human face. Temperature on the other hand is an absolute measure of how cold or warm a parcel of air is. Wind chill is a calculated measure of the cooling effect that the wind has on the body in cold, dry air masses, it's not a measured value. The arrival of arctic air masses in the winter are often accompanied by a period of strong gusty wind which acts to amplify the impact that the cold has on the human body through wind chill. ![]()
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