Dressing for Survival and Comfort
Understanding how your body loses and gains heat will prepare you to stay comfortably dressed in any environment.

How We Lose Body Heat
To understand how to choose the best outdoor clothing, you must also understand how the human body loses its life-sustaining heat. Four principles govern heat loss:

1. Conduction, the first principle, arises from nature’s desire to create a balance in all things - in this case, a heat balance. Whenever your skin touches a surface warmer than your skin, heat moves away from the object and warms your skin and vice versa. The greater the difference in temperature, the faster the heat transfer. Clothing needs to create a protective, insulating barrier between your skin and anything you might touch that will conduct heat away from you.
   
   
2. Convection describes heat lost by way of air or water movement. Your body constantly maintains a thin layer of warm air next to your skin. Wind slicing through your clothing tears away that thin layer which your body immediately replaces. In a high wind, you can lose a substantial amount of heat in a short period of time. You will need windproof clothing to prevent convective heat loss.
   
   
3. Radiation refers to infrared heat loss from a warmer object to a colder object. Exposed skin radiates a significant amount of heat into the surrounding environment, and on an average day, you’ll lose more body heat through radiation than through any other mechanism. Since the blood vessels in your head do not constrict when exposed to cold, heat literally blasts out of your exposed head on a winter day. So covering your head allows body heat to be transferred to other areas keeping you warmer overall. Feet cold? Put on a hat! Adequate clothing for your head and neck is essential to your outdoor wardrobe in order to keep radiant heat loss to a minimum.
   
   
4. Evaporation, the escape of heat through the vaporization of moisture, constitutes the major source of acute body heat loss. Breathing accounts for up to one-third of evaporative heat loss. On a hot day, the evaporation of sweat from your skin keeps you from overheating. Pour on a little water, and evaporation cools you even faster. On a cold day, the evaporation of sweat or water can suck a tremendous amount of heat out of your body. Clothing needs to allow sweat to exit without vaporizing and taking body heat with it. Ideal clothing needs to keep rain or snow from adding moisture to your skin at the same time it allows sweat to exit.
   

Clothing Material
Designer jeans and cotton sweatshirts look fine strolling the local mall and may keep you adequately protected on a warm, cloudless summer day on the trail, but bring on a sudden storm and that same outfit can become a major source of discomfort.

Walk into any store that specializes in outdoor clothing and get ready for a deluge of choices in materials with high-tech names and labels promising a long list of wonderful performances. Relax. Almost all fabrics used in the construction of outdoor clothing, with relative advantages and disadvantages, fall into three categories: cotton, wool and numerous synthetics.

COTTON
Few people would argue that cotton ranks as the most comfortable fabric next to your skin. Because cotton “breathes” well, it allows perspiration to escape easily into the air. Cotton also absorbs a lot of water, and that increases evaporative heat loss. Cotton, therefore, rates as an excellent choice for hiking in desert regions in the daytime in the summer. But cotton’s tendency to cool you rapidly, makes it a poor choice for cold environments. Many of the best-dressed corpses ever dragged out of the woods were wearing cotton.

WOOL
For centuries, wool has been worn by people around the world who spend time outdoors and offers vast advantages over cotton. Wool fibers conduct heat poorly, which means they provide excellent insulation - even when wet. Unprocessed (“virgin”) wool retains oil from the sheep who sacrificed their “clothing,” allowing it to dry much faster than cotton. You can wring water from wool clothing, put it back on, and wear it all day without losing much body heat. And, if the rain stops, it will dry while you wear it.
More durable than cotton, wool does have its negative side. It tends to be heavy and bulky compared to cotton, and it takes more care. Wool, for instance, shrinks when washed in hot water or left in the clothes dryer. And, some people can’t stand the feel of it against their skin.

SYNTHETICS
Synthetics, in simple terms, are made from plastic woven into thread, which is woven into all kinds of clothing. They generally fall into three classes: undergarments, mid-layer garments (sweaters, jackets, vests - often referred to as pile or fleece), and outer-layer garments usually called “shells.” Synthetic fibers are stuffed into synthetic shells to make parkas for extreme cold. Synthetics conduct little heat, even less than wool, making them the best choice for staying warm. Synthetics absorb almost no water and actually transport moisture away from your skin - a process referred to as “wicking.” This makes them the best choice for staying dry. They are lighter than wool, compress more than wool for easier packing and stand up fairly well to hard use. Synthetic clothing is generally the best choice for outdoor comfort and for surviving the unexpected.

In the minus column, synthetics, being plastic, melt at relatively low temperatures. You can ruin a good pair of synthetic gloves picking up a hot pot. Unless you purchase special wind-blocking fleece, synthetics allow icy breezes to blow through freely. And, synthetics tend to hold onto bad odors such as those produced by a sweaty body.

Choosing the Right Outdoor Clothing
Murphy’s Law assures you that if it has snowed once in July in the last 50 years it will snow on the day you choose to fish that high mountain lake. Go prepared for the worst possible conditions you can expect in your area of travel.
A quick phone call to the local managing agency (U. S. Forest Service, National Park Service, etc.) and you’ll know the worst conditions ever recorded where you intend to travel. Choose your clothing for those conditions. Far better to regret carrying a few extra pounds than to sit shivering, wishing for a sweater you left in a closet back home. Here’s the most important clothing tip of all: Dress for the worst possible conditions you can expect in your area of travel.

1. Clothing should provide comfort and ease of movement and should not restrict circulation. Loose-fitting clothing is typically the best choice, but some new stretch synthetics fit snug while providing the same comfort and ease of movement as loose-fitting clothing.
2. Clothing should provide insulation. Clothing works as insulation by creating dead air spaces, air trapped between the fibers of the garment, which protect you from conductive and radiant heat loss. The best clothing does not lose its ability to insulate even when wet with water or sweat.
3. A windproof and waterproof outer shell should be available at all times to protect you from convective and evaporative heat loss. Windproof does not always mean waterproof. Read the label.
4. Double-stitched seams, strong zippers and reinforcement at areas of stress (such as elbows, knees and seats) are usually worth the money.
5. Functional designs that include large pockets that fasten and unfasten easily, roomy hoods on parkas, leg zippers on wind and rain pants, and adjustable closures on wrists and ankles are usually worth the money.