by Larry Wiggins

Created on: January 25, 2009

The choice of clothing and equipment for a winter trip is extremely important. This choice can make the difference between an enjoyable trip and an uncomfortable, possibly unsafe expedition. In order to make a choice, you need an understanding of how heat is transferred away from the body and the negative effect of moisture in staying warm.

The heat transfer mechanisms that are of primary concern when hiking are conduction and convection. Convection cooling when hiking is primarily through air flow carrying heat away from the body. The primary method to combat convection is through a wind break layer. Usually this is a relatively thin layer of nylon worn as the outer most layer.

Conduction is the second method of heat transfer of concern. This type of transfer is between two materials that are in direct contact with each other. Conduction is easiest understood from feeling the cold from sitting on a rock. The cold from the rock is transferred by conduction from the rock into the body. The purpose of insulating layers is to provide a physical barrier between your body and the cold. Many of the insulating layers are bulky because they use air space as a portion of the insulation. The integrity of the air space is maintained by the wind break layer.

During the winter, moisture is the enemy of staying warm. Clothing systems then are most effective when they block wind, provide insulation and keep moisture out of the clothing system and away from the body. Most people understand that it is necessary to stay dry from external sources such as rain or the snow. Rain suits and avoiding the snow on non-waterproof clothing is obvious. What many people do not understand is that in our daily activities, the body expels a large amount of moisture through breath and perspiration. This source of moisture must be considered in a clothing system.

Since perspiration is a bodily response to cool off the body, staying comfortably cool is important in winter. You can adjust your body temperature by using a layering system consisting of several thin insulating layers under a wind break. As you exercise and become warmer, you need to doff one or more of these layers. If you take a break or finish your hike be prepared to add layers back to the system. I know personally that when I am backpacking, I generate a lot of heat. I will start a 40 degree F day in shorts and light shirt because of this. I just make sure that I have appropriate layers to put on when I finish hiking. One large,

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