Staying Warm In The Cold
If you want to stay warm in the cold, you must:
- Keep moving – muscular work generates heat.
- Keep eating – you need lots of energy to keep your body working in the cold; also eating boosts your metabolism.
- Keep drinking – your body needs water to function properly and maintain circulation to your extremities. Dehydration leads to hypothermia and frostbite.
- Stay dry – try to sweat as little as possible (pace yourself) and change out of wet clothes when you stop for the night.
- If you are not moving around, you will need very warm clothes, boots or a sleeping bag to keep you warm.
Turn up the Heat: When you are cold at home, you turn up the heat. Our bodies don’t work that way. Heat is a waste product of metabolism. To turn up the heat, we have to increase our metabolism by exercise/exertion and/or eating (eating increases metabolism by about 10%).
A basic understanding of the physics of heat loss will aid in your ability to keep yourself warm. Our bodies lose heat to the environment by Conduction, Radiation, Convection, and Evaporation:
Conduction is the direct physical transfer of heat. Examples include using a sleeping pad to insulate you from the cold ground and the instant frostbite that results from spilling sub-zero fuel on your hands.
Radiation is the constant dissipation of heat outward from our warm bodies. Insulation, such as thick clothing layers, traps warm air and keeps radiated heat close to our bodies.
Convection, also known as windchill, is the heat lost through air movement over our skin. Windproof outer layers limit the wind chill effect – in severe conditions, don’t forget windproof hats, face masks, and mittens.
Evaporation is the heat we lose through sweating and exhaling warm moist air. You can control evaporative heat loss, by not letting yourself get soaked with sweat. Vapor barriers (e.g. a plastic bag over your socks) limit evaportative loss and keeps your feet much warmer, although sweaty, be sure to dry out your socks,boots and liners at night.