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Polar Vortex

Author(s): Gregory L Vogt, EdD

NWS Windchill Chart

The National Weather Service  Windchill Temperature (WCT) index uses advances in science, technology and computer modeling to provide an accurate, understandable and useful formula for calculating the dangers of winter winds and freezing temperatures.

The WCT:

•calculates wind speed at an average height of five feet, the typical height of an adult human face, based on readings from the national standard height of 33 feet, the typical height of an anemometer; •is based on a human face model; •incorporates 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; and •assumes no impact from the sun (i.e., clear night sky). •

Image Credit: National Weather Service, http://www.nws.noaa.gov/om/windchill/index.shtml