AMC Outdoors, December 2005
I hate being cold. I mean, really, what is there to like about wooden toes, body-racking shivers, and freezing fingers? But I love being in the cold. The air snaps like a tonic, infinite views stretch through a transparent atmosphere, and snow-covered woods whisper the quiet of solitude. Warmth becomes a joy, a commodity to be savored as it cocoons your body in a gentle embrace.
Prepared with the right knowledge and gear, you can be perfectly comfortable in virtually any conditions. The trick is to understand a few basic truths. First of all, winter clothing isn’t warm by itself, nor does it generate any heat. You, on the other hand, are a biological furnace. Your body constantly produces energy in its efforts to maintain a steady temperature of 98.6 degrees. Thus the purpose of your clothing is not to create heat, but to trap it next to your body before it can escape into the frigid atmosphere.
When selecting your winter wardrobe, always dress in layers so that you can easily adjust your outfit to match changing conditions. Keep in mind that the more dead air space there is within your clothing, the more heat it can retain. Consequently, all other things being equal, the thicker your layers, the more air they’ll trap—and the cozier you’ll be. When it comes to staying warm, anything that steals heat away from you is BAD, and can lead to an unpleasant (even dangerous) cold-weather experience. So to stay comfortable and safe, you need to address—and mitigate—three primary forms of heat loss: convection, evaporation, and conduction.
Keep ill winds at bay
Moving air whisks away body heat. Wind is the most obvious culprit, and you should always wear an outer wind-breaking layer in cold, breezy conditions. Less obvious, however, is the convection that naturally occurs inside your clothing. Warm air rises. This means that your precious body heat will move upward through your clothing and escape out of any available outlets, especially in openings around your neck. As it departs, it is replaced by colder air drawn in from gaps lower down, a natural circulation that methodically strips away body heat. To prevent this, make sure that your clothing forms a tight seal around both your waist and wrists. By eliminating these inflow points, air circulation is greatly reduced and the warm air lingers for your enjoyment.
A corollary of this is the “bellows” effect. If your clothing layers fit loosely, lots of large air pockets will be sandwiched between them. Any time you move, and your clothing shifts and compresses, warm air is forced out of these gaps. As they expand once again, colder air is sucked back inside…brrrr. The solution: Wear layers that fit as snugly as possible without being constricting, with as little space as possible between them.
Don’t sweat it
It takes a tremendous amount of energy to transform water to vapor. If you have moisture—especially sweat—next to your skin or trapped within your clothing, it will suck away body heat at an astonishing rate as it evaporates. To minimize this, never wear cotton, which absorbs up to 60 percent of its weight in water and can stay damp almost indefinitely. Instead wear synthetics like polyester or nylon, which absorb only 1 to 3 percent of their weight and will dry rapidly. To avoid moisture build-up in the first place, establish a pace that minimizes the amount you sweat. If you find yourself over-heating, strip off layers. Remember that if you are comfortably warm standing still, you will rapidly become too hot once you start moving. Shed layers before you start, even if you briefly feel cold.
Moisture build-up is particularly problematic around your feet—the second sweatiest part of your body after your armpits—and damp socks will rapidly banish your toes to the deep freeze. To keep your toes happy and snug, consider wearing a fast-wicking synthetic liner sock beneath a heavy wool sock. This will move moisture into the outer sock and help prevent wetness from building up directly against your feet. Even better, consider adding a vapor barrier liner between these two layers, which will both reduce the amount your feet sweat as well as keep the outer sock entirely dry.
Conduct yourself poorly
If two objects of unequal temperature are placed in contact with each other, they will rapidly equalize to the same temperature. If one of those items is you and the other is snow, ice, or any other cold surface, heat will flow away from your body and into the colder surface. But the rate at which this happens varies dramatically depending on how easily the two materials transfer, or conduct, heat. Some do it rapidly, such as ice or metal, while others transfer heat much slower, such as foam or wood.
When out in the cold, avoid sitting directly on the snow or other cold objects. Instead, carry a small piece of closed-cell foam with you at all times. A sleeping pad works well, or you can also just sit on your backpack—the hipbelts on most larger packs are good insulators. This winter, don’t let dropping temperatures get you down. Use these techniques to stay warm, and get out and chill in comfort.
—Matt Heid is Senior Editor of AMC Outdoors.