Adventist Youth Honors Answer Book/Maintaining body warmth

The key to staying warm in the winter is to stay dry. This is done by dressing in layers which are easily vented. While snow shoeing, hiking, or cross country skiing, an individual generates an enormous amount of body heat. Unless the person is careful, the body will overheat, and the person will begin to perspire. When the person stops to rest, the perspiration will begin to chill the body. It is therefore imperative that the active person dress in layers. When the body begins to heat up, the outer jacket should be vented, which is to say, unzipped. If heat continues to build, the outer jacket should be removed. If this does not cool the body enough to end perspiration, another layer should be vented, and perhaps shed. Eventually, the clothing will match the person's level of activity, where enough body heat is generated to keep the person warm, but not sweaty. If it is snowing, sleeting, or raining, be sure the outermost layer is waterproof.

If a person finds that he (or she) has not controlled his (or her) perspiration sufficiently, it is important to change out of the sweat-soaked garments as soon as possible. For once the chills set in, they are difficult to overcome. Do not wear cotton garments for winter camping. Cotton will keep you warm only if it is kept perfectly dry, and keeping it perfectly dry is nearly impossible. Winter campers are quick to admonish that cotton kills. Instead wear woolen or synthetic garments.

When the day's exertion ends, it is time to start adding layers again. When it is finally time to go to bed, the winter camper should climb into a warm sleeping bag and zip up. Sleeping bags are generally given a temperature rating. It would be foolish to set out on a winter camping expedition with a $10.00 sleeping bag that is only good down to 40°F. Make sure the temperature rating matches the expected conditions, and reserve a little margin for bad forecasting. Also, don't forget that weather forecasts often do not cover higher elevations, so if you're hiking in mountainous areas, be aware of the conditions at the altitude you're going to be spending your time. Again, if perspiration begins, the bag should be partially unzipped to allow the air to cool the body before sweat does.