We use the term "Wind Chill" a lot in the winter when describing the current weather and how it feels outside, but what exactly is it and how is it calculated?
Thermal radiation and wind speed
Wind chill refers to the approximate temperature that the air feels on human skin in cold weather, factoring in the ambient air temperature and wind speed. As heat is radiated from a person's body, a thin layer of warm air surrounds the person acting as a barrier between the person and the cold air. As winds increase, that warmth is drawn away, further increasing the rate at which the heat loss occurs. Moisture in the epidermis, the outer layer of skin, is evaporated by the drier winter air and the process of evaporation then increases that heat loss, even more, exposing the skin to damage. Frostbite can develop in just minutes, depending on how cold the temperature is and how strong the wind speed is.