For those that live in Canada or the northern tier of the United States, winter can bring miserable weather. Snow, as well as bone-chilling air, can take up residence and never seem to leave. Then there is the wind chill factor, an item that frequently pops up on the weather maps and is referred to quite often in weathercasts during the winter season. So what is it and how did it come into effect? These are some of the questions that I will explain, as I break down the “chilling facts” about Wind Chill. Wind Chill can be explained as a combination of winds and cold temperatures, and basically, how cold the air appears to be when the wind is blowing. Even though the wind chill is given as a temperature, it’s not really a different kind of temperature. What it means in practical terms, is that if the antifreeze in your car’s radiator is good to 10 degrees Fahrenheit and the temperature drops to 21 degrees Fahrenheit, you do not have to worry, even if your car is out in a 20 mph wind that drops the wind chill to -9 degrees Fahrenheit. As long as the actual temperature does not fall below 10 degrees, the fluid in your car’s radiator will not cool below -9 degrees, no matter how hard the wind blows
The term “Wind Chill” came about by Antarctic explorers Paul Siple and Charles Passel, after conducting experiments on the time needed to freeze water in a plastic cylinder that was exposed to the elements. They found out that the time needed to freeze water was dependent on how warm the water was, the outside temperature and wind speed. The reason for this experiment, theoretically, was to eventually determine at what rate the body loses heat when exposed to the cold and the wind, so that the public would be able to protect themselves from hypothermia, frostbite and other cold-related ailments. A Wind Chill Index (W.C.I.) was created in the 1940’s and had been used until closer inspection of the numbers revealed that the W.C.I. was too cold and thereby wrong. The problem with the original W.C.I. was caused by the fact that human skin freezes at a different rate than water. One person that recognized how wrong the W.C.I. was, was Maurice Bluestein, a mechanical engineer. While shoveling snow on a day that saw a temperature of -26 degrees F Bluestein noticed that his exposed skin was not freezing in 15 seconds, as it should have done if the wind and the cold were the equivalent of -75 degrees Fahrenheit! After some research, Bluestein found that Siple and Passel had assumed that the temperature of human skin was 90 degrees Fahrenheit, instead of our skin being closer to 50 degrees on a really cold day; they had also placed the containers 33 feet above the ground, where wind speeds are higher than the height of a person; and they took their measurements where it is far colder than where most people live.
After years of tinkering around with how to improve the index, it was not until the beginning of the 21st Century, that improvements finally took place on the old formula and in the fall of 2001, both Canada and the United States had incorporated the “new” wind chill index, by posting them on their respective weather service websites. The current formula uses advances in science, technology and computer modeling, in order to provide a more accurate and useful formula in calculating winds and temperatures. Some of the specifics are as follows: 1) The new W.C.I. calculates wind speed at an average height of 5 ft. ( typical height of an adult human face) instead of a height of 33 ft. above the ground. 2) Is based on a human face model ( how fast does human skin freeze instead of water) 3) Incorporates modern heat transfer theory ( heat loss from the body to its surroundings, during cold and windy days)
Even after the new index became widely used, Dr. Bluestein admitted that no two people can feel the cold the same way, with some people retaining heat better than others. Folks with better insulation, or fat, may feel the cold more quickly than those who are not as well insulated, and that is because fat traps the heat in the body’s core, away from the skin, which then gets cold. Also, the time of day matters, and whether a person is standing in the sun all comes into play. So, as you can see, the science of meteorology is gradually reshaping itself in order to keep up with the times. By improved computer modeling, the W.C.I. now gives you the most accurate of information in order to protect yourself from winter’s wrath. So the next time you are about to step out into the cold, and/or watch the latest weather report to see how chilly it is, give thanks to Maurice Bluestein’s inquisitive nature. Refining the wind chill chart has helped your favorite local weatherman get the temperature right more often than not during the winter months, making his forecast more accurate and not full of hot air!