4/25/2024 0 Comments Old wind chill chart to newIn spite of its shortcomings and the many efforts to develop a more comprehensive measure of cooling discomfort, Siple's simple expression continues to gain acceptance. Whether the person is running, walking or just sitting whether the sun is shining the humidity a person's age, physical condition and health the amount and insulation quality of garments worn - all can affect the rate of cooling of the human body. It does not take into account many other factors important for determining a person's sensitivity to cold. The Siple-Passel approach is only an estimate of the discomfort felt by humans under various temperature and wind conditions. Of course there is a considerable difference between water-filled plastic tubes and a person properly clothed for the weather. Later, the formula was modified to allow computation of a wind chill equivalent temperature. They developed a formula for relating heat loss to wind speed and air temperature, expressed in units of atmospheric cooling eg, watts per square metre. During the second expedition of Admiral Richard Byrd, Siple and his partner Charles Passel conducted experiments at Little America, Antarctica, on the time required to freeze water in plastic vials exposed outside in the wind. The famed polar explorer and geographer Paul Siple first used the term in 1939. Of course, the hot chocolate would cool down to room temperature in any case, the blowing simply speeds up the process. Likewise, no matter how strong the wind blows, it cannot lower the temperature below that of the surrounding air. But you cannot make it colder than that, no matter how hard you blow. Wind cooling is what happens when you blow on a mug of steaming hot chocolate to cool it to room temperature. The more pronounced the air movement (wind or moving air produced by walking, skiing or riding in a convertible) and the greater the temperature difference between the surface of the object and the air, the greater the heat loss. Inanimate objects that have no heat to lose - a mail box or metal fence, for instance - are not really affected by the wind at all. The effect of wind is to lower a person's temperature by evaporating moisture on, and blowing heat away from, the skin. The loss of body heat increases with a rise in wind speed, so that at the same temperature, a person will feel colder when the wind is blowing than when it is not. Wind chill is the popular name used to describe what cold WEATHER feels like at various combinations of low temperature and high WIND.
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