Meaningful wind chill indicators derived from heat transfer principles

Area of Science:

• Environmental Science
• Human Physiology
• Thermodynamics

Background:

• The wind chill index (WCI) and wind chill equivalent temperature attempt to quantify human comfort by combining temperature, wind velocity, and solar radiation.
• Despite its widespread use since 1945, the WCI has faced criticism for not aligning with modern heat transfer principles.
• While the WCI has shown success in predicting cold discomfort, it is not directly measurable and lacks inherent physical meaning without calibration.

Purpose of the Study:

• To critically evaluate the existing wind chill index (WCI) and its limitations.
• To introduce and validate new, measurable wind chill indicators based on established heat transfer principles.
• To provide a more accurate and physically meaningful assessment of cold exposure and human tolerance.

Main Methods:

• Analysis of the theoretical underpinnings of the current wind chill index (WCI).
• Development of novel wind chill indicators: exposed skin temperature and maximum exposure time.
• Correlation of the WCI with measurable variables representing the sensation of cold and heat loss from bare skin.

Main Results:

• The study demonstrates that the WCI reflects the instantaneous rate of heat loss from exposed skin.
• The WCI correlates reasonably well with measurable cold sensation variables.
• Two new, measurable indicators—exposed skin temperature and maximum exposure time—were introduced, offering greater informational value and physical meaning.

Conclusions:

• The WCI, while useful for predicting discomfort, is an unmeasurable proxy for heat loss.
• Exposed skin temperature and maximum exposure time are proposed as superior, measurable alternatives to the WCI.
• These new indicators are grounded in heat transfer theory and provide a more scientifically robust assessment of cold exposure.