- How do explorers keep warm in Arctic climates?
- Do fabrics differ in their ability to keep the wearer warm and dry?
- Which is more important in frigid temperatures--keeping dry or staying warm?
- a material or fabric that helps a person retain heat
- a system of wearing clothes in layers to provide maximum warmth and dryness. An effective system allows a person to adjust for a wide range of climatic conditions.
- very thin fibers tightly woven. They trap warm air in clothing and cut heat loss.
- moisture loss:
- moisture lost through pores in our skin and through our noses and mouths as we breathe
- sythetic fabric:
- material made from fibers that do not occur naturally. Nylon is an example.
- the act of absorbing moisture and moving it away. A fabric that wicks perspiration absorbs sweat on the skin and moves it to an outside layer of material, leaving the fabric next to the skin relatively dry and helping the person stay warm.
OverviewBlustery winds whirl around the explorers as they pitch their tents. They've just finished ten hours of sweat-producing activity--skiing and dog sledding in frigid Arctic conditions. But these people stay warm and dry, thanks to specially designed clothing and high-tech fibers. To decide which synthetic fabrics to wear, explorers need to decide what they want their protective clothing to do. If they want it to repel water but still "breathe," they might choose fibers such as nylon or polyester or waterproof, breathable laminates and coatings. Many fabrics contain a combination of fibers. For example, if your jacket has hydrophilic (water-loving) fibers on the outside and hydrophobic (water-fearing) fibers near your skin, the inner fibers will push moisture away from your skin while the next layer of fibers will pull the moisture outward. Keeping dry is as important as keeping warm when it comes to survival and comfort in the Arctic. An adult normally loses about one liter of water a day through evaporation from the skin and lungs. During a day of strenuous activity, a person can lose ten liters of water. As the body burns energy during physical exertion, it creates heat. It then produces sweat, which provides a cooling effect as it evaporates. A sweaty person in wet clothes can lose heat rapidly if inactive in frigid temperatures. Each member of Will Steger's team will wear five layers of clothing that provide insulation. Explorers can peel off or put on layers as weather conditions and activity levels change. The first layer consists of long underwear made of a lightweight, synthetic material that allows perspiration to move away from the skin to the second layer, a synthetic fleece shirt and pants. As it wicks moisture away, the quick-drying fleece helps the underwear layer provide warmth. Next, a jacket covers the first two layers, offering insulation. Made of a heavier fleece designed for use in extreme cold, the jacket has two-way underarm zippers (as do garments in the top two layers) to help the explorer regulate body temperature. The fourth layer, a lightweight second jacket made of very fine, tightly woven microfibers, slows the rate of moisture loss. The final layer--a durable storm shell that is waterproof and breathable--protects against wind, rain, and snow. The shell is laminated with a film containing microscopic pores that allow water vapor (sweat) to escape while keeping moisture out. Team members also wear mukluks, flexible boots designed by the Inuit people and made of animal hides and canvas. Sled dogs, too, wear booties as protection from rough ice and snow.
- What fabrics do you normally wear? Which are the warmest and which keep you cool? Do some fabrics allow more air movement than others?
- What difference does a hat make in regulating body temperature? Do you notice a difference when you take off a hat you've worn for several minutes?
ActivityPeople lose moisture through evaporation from pores in the skin. When you're hot and begin to sweat, your rate of respiration speeds up in an effort to cool your body. Skin moisture can evaporate rapidly in a dry climate, even when you're not sweating. On average, an adult loses about one liter of water a day. When working hard and burning energy that produces heat, that person's water loss quickens proportionately. Create a lab that demonstrates aspects of water loss from your body.
- one plastic bag per student, or plastic wrap
- masking tape
- paper and pencil
- Cut the plastic bag into a single-layered square large enough to fit comfortably around your forearm. Place the piece of plastic around your forearm and tape it securely (but not too tightly) at top and bottom.
- Wear the plastic over your forearm for at least ten minutes. Meanwhile, in teams of four people, take and record your pulse and respiration rates. Then walk up and down a flight of stairs five times. Record your new pulse and respiration rates. Next, run up and down the stairs five times and then record pulse and respiration. (If your school has no stairs, use a hallway or a walkway outside.)
- After the exercise, note whether the plastic contains any water condensation released by your skin as it performed respiration and perspiration.
- Take the bag off and feel the moisture on your skin where the plastic had been. Note the moisture level of the skin that was under the plastic as compared to skin exposed to air during the ten minutes.
- What is the effect of moisture evaporating on your skin?
- How much fluid does a person need to consume each day to replace regular moisture loss?
- Do we lose only water, or do we lose other essential elements through evaporation as well?
- Forgey, W.W. (1985) Hypothermia. Merrillville, IN: ICS Books, Inc.
- Getchell, D., et. al. (1993, Sept) Wild clothes: 1993 guide to functional
outdoor apparel. Backpacker, pp. 61-80.
- Randall, G. (1994) The modern backpacker's handbook. New York: Lyons & Burford.
- Sierra Club, San Diego Chapter. (1993) Wilderness basics: The complete handbook for
hikers and backpackers (2d ed.). Seattle: The Mountaineers.
- Townsend, C. (1994) Wilderness skiing and winter camping. Camden, ME: Ragged
- Wilkinson, E. (1992) Snow caves for fun and survival (rev. ed.). Boulder,
CO: Johnson Books.
Additional sources of information
American Textile Manufacturers Institute
1801 K Street NW, Suite 900
Washington, DC 20006
Institute of Textile Technology
2551 Ivy Road
Charlottesville, VA 22903-4614
Specialist at an outfitter company
Store that sells camping gear and outdoor clothing