Wind Chill: Whole Body vs. Facial Cooling

Abstract : This report examines the question of whether windchill should be calculated as an effect of exposed skin heat transfer or of whole body heat loss. Theory suggests that it is not possible to derive a useful index of windchill based on heat transfer through normal outdoor winter clothing. A test is described that demonstrates that one proposed index, AT, which is based on a clothed, whole body model, does not consistently and uniquely correspond to levels of human sensation. That is, the same value of AT results from wind and temperature combination that produce different cold sensations. Refinements to the DCIEM Facial Cooling Model to include a variable internal thermal resistance, dependent on skin temperature, are described. This model of windchill is based on cooling of the windward side of a cylinder. Any equivalent temperature calculated with this model corresponds to only a narrow range of thermal sensation.