Stay Warm by Dressing Like a Mountain Goat
Perhaps no mammal in Utah is better suited to surviving outdoors in winter than the mountain goat, which goes about its daily business making few concessions to the wind and cold.
Humans can learn a lot about staying warm outdoors by examining the mountain goat. A subcutaneous fat layer deposited during late summer and fall, and a thick hide, help this animal to survive - even to thrive - in cold weather. A dense fur covers everything but its muzzle and hooves. Upon closer examination, we learn that this fur actually consists of two layers. A fine, densely interwoven wool wraps the animal as if in a cashmere sweater, and on top of this grow long, coarse guard hairs that may reach eight inches in length. These hairs are hollow, so they trap air within each strand, adding to the superior insulating qualities of the goat's coat.
The nearly hairless human body is covered with a comparatively thin akin, providing little natural insulation against extreme cold. But the layering concept built into a mountain goat's body can be adapted to human clothing, and becomes an important concept for winter dressing.
Three essential layers are identified for work and play outdoors in winter: underwear, insulation, and shell.
Underwear provides basic insulation and it can wick moisture away from our skin, reducing the effects of evaporative cooling when we perspire. Natural fabrics like silk, wool and cotton are a good choice for warmth in low-exertion activities like ice-fishing. For high-exertion activities like cross country skiing, underwear made of a synthetic fabric designed to transport moisture away from the body is a better choice. Modified polyesters like REI's MTS (Moisture Transport System) and Patagonia'a Capilene are examples of these synthetic fabrics. The insulation layer comes next, and like the goat's fat, thick hide and wooly layers, a human's insulation layer might turn out to be more than a single garment. These layers can be fashioned from natural materials like wool and down, or synthetic fibers.
Down is an excellent insulator. Lightweight and extremely warm, down is also quite compressible, a considerable benefit if the garment will be carried in your pack. Down must be kept dry, however, because when it becomes wet and the feathers matt together, its insulating value is lost.
Wool is durable and breathable, and will still insulate when it is wet, but it can be heavy and bulky to carry.
Batted fibers, that are synthetics manufactured in bundles, include Polarguard, Thinsulated, and Quallofil. These tend to be a little heavier and bulkier than down, but they will not absorb water, and so tend to insulate even in wet conditions. Some of these materials, like Quallofil, are hollow strands similar to the goat's outer guard hairs.
Pile garments are made of a plush, non-piling polyester and have a "warm and fuzzy" feel. They provide excellent insulation when wet and dry quickly, but they are not windproof. All of these insulating layers should be covered in windy or wet conditions with a shell. The shell can also be used as a single insulating layer in warmer weather and high activity times.
Waterproof and windproof fabric like the synthetic rubber Hypalon are good for low exertion activities generating little perspiration. A waterproof/breathable material that allows moisture vapor (perspiration) to escape while preventing water droplets (rain and snow) from entering is needed for high-exertion activities. The most well-known of the waterproof/breathable fabrics is Gore-Tex, which is actually a membrane laminated to any of a variety of fabrics. Others like Ultrex, H2N0 and Helly-Tech are coatings applied to fabrics. Shell garments can also be insulated, as is popular with downhill ski jackets, although these are less versatile for changing activity levels or varying climate conditions than separate layers.
Along with sweaters, vests and jackets, socks, pants, hate, neck gaitors, hoods, headbands and gloves are other components of the layering system to be considered when deciding what to wear or take along on a winter outing.
Since types of fabrics, coatings and fill materials vary widely, be sure to read and follow the care instruction tags sewn onto each garment.
The layering concept is an important one, but equally important to remember is that your layers are designed to do just one thing - to hold in the body's heat. In order for the layering concept to work efficiently, the body must be burning fuel and producing heat. A mountain goat's heart beats faster than ours, and its body temperature is about four degrees above ours. In cold weather, the animal benefits greatly from the heat of fermentation in its ruminant digestive tract. Since we cannot claim these physiological advantages, we humans must keep stoking the internal fire with high-energy foods and warm drinks. Remembering this, and dressing in layers, will help you to better enjoy the great outdoors in winter.