Staying Comfortable

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Understanding the Mechanisms of Heat Loss

Clothing does not necessarily provide comfort; rather it allows us to control the elements of discomfort. Heat is the primary element of discomfort, well enjoying time outside our goal is minimize excess heat as well as heat loss. We lose heat through 3 mechanisms; evaporation, conduction and convection. Excessive heat loss through these mechanisms will leave you cold and uncomfortable in cooler weather.

Evaporation is necessary, it is the body’s way of cooling down when overheating. Heat loss occurs when your body transforms vapour perspiration into liquid sweat. Clothing layers must breathe in order to manage vapour perspiration. If you are wearing layers that do not breathe, you may begin to accumulate moisture in the inside of clothing, resulting in your clothes getting damp.

Conduction is the transfer of heat directly through physical substance. Wet conductive heat loss occurs roughly 25 times faster than dry conductive heat loss (place one hand in ice water and one in the freezer- the one in the water will cooler roughly 25 times faster than the one in the freezer). Wet clothing layers cause accelerated heat loss which equals discomfort. To manage conductive heat loss, insulating layers must be kept dry from the outside elements like rain and snow and from the inside from your bodies precipitation.

Convection is the heat loss caused by the movement of cool air in your environment. Your outer layer must be highly wind resistant or windproof to prevent excessive convective heat loss. Also, the design of your windproof outer layer can minimize convective heat loss through features such as; water tight zippers/ storm flaps over zippers and having draw cords at the waist and/ or hem of your jacket. These features contribute to sealing your outer layer from cool winds.

Remember to stay dry and comfortable, match your clothing layers to the anticipated weather and activity. As the outside weather or your activity level changes adjust your layers accordingly. If you are unable to adjust your layers reduce your activity level.

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