Theoretical Wind Chill Model With Experimental Verification

Abstract

In the late 1990s, the National Oceanic and Atmospheric Administration (National Weather Service) requested the development of a replacement for the Siple and Passel wind chill model. Bluestein and Zecher responded with the development of a model that failed to meet expectations because of its inherent errors. That failure led to the development of this model. This model has two major components. The first is an equation for accurately determining the wind chill temperature. The second is an equation for precisely calculating the facial freezing time. This is the time after the initial exposure to a cold ambient when an individual's face will experience freezing. The model is based on the major forced convection and radiation heat losses at the facial surface. Included are the facial heat gains due to sunshine and the individual's physical activity and a lesser evaporative heat loss due to this activity. It also includes the effect of altitude and a possible facial immersion in a ground surface boundary layer. The model has been validated experimentally. It is applicable to all individuals engaged in a wide range of physical activities in either the presence or absence of sunshine. In addition, the model is adaptable over a wide range of ambient temperatures, wind velocities, altitudes, and geographical locations worldwide.