Maintaining your core body temperature is critical in a survival situation. Hypothermia can set in even at relatively mild temperatures. A fact that is often lost on many people is that heat is energy and cold is merely the absence of that energy. Heat is a “thing” where cold isn’t. This is an important distinction so you’ll better understand the different ways heat is lost and how to prevent it from happening.
Different Types of Heat Loss
Conduction is the loss of heat through direct contact. Sitting on a cold rock can give you a chill, even if you’re otherwise sheltered from the elements. Your body heat is being leeched away by contact with a cold surface. The best way to prevent this is by insulating your body from the ground, such as sitting on a foam pad.
Ever been outside and have a sudden cool breeze give you a bit of a shiver? That’s convection at work. Think of your body as being encompassed by a thin layer of air that is constantly being warmed by your body heat. This “bubble” sort of insulates you a bit from the rest of the world. When a breeze or water flows past you, it can remove that bubble, causing you to feel cold. We combat this by wearing clothing that traps that air bubble around us.
Radiation is how we lose the most heat energy. We constantly radiate heat from our bodies, some at greater rates than others. If you’ve ever cuddled an infant, you know just how much of a little “hot box” they can be, right? We reduce the effects of heat loss through radiation by covering up, trapping as much of that radiated heat as we can.
When we exert ourselves, we begin to sweat. When we’re working hard, we heat up and our bodies try to cool us down by perspiring because evaporation is a cooling process. The problem comes in, though, when we’re trying to stay warm. When we’re fighting for survival in a cold climate, we want to avoid sweating as best we can.
Sweat not only robs us of body heat, the moisture can get trapped in our clothing, which can be detrimental to the insulating properties of our attire. This is why dressing in layers is important. As your work level increases, remove one or more layers of clothing to moderate your body temperature. Then bundle back up as you cool down.
Preventing Heat Loss
As a general rule, moisture is detrimental to survival, at least when it comes to maintaining our core temperatures. Water is a fabulous conductor of heat energy. It absorbs heat quickly and whisks it away from you. This is why it is vitally important to stay as dry as you can and, should you have the misfortune to get caught in a downpour or perhaps stumble into a stream, get a fire going as quickly as possible to dry yourself out.
This is also why constructing an expedient (emergency) shelter is important. Getting out of the elements helps prevent heat loss through convection (by reducing or eliminating the wind blowing across your body) as well as through evaporation (by keeping you dry). In a properly constructed shelter, your body heat will warm up the confines through radiation and you’ll insulate yourself from the ground to prevent heat loss through conduction.
See how it all works together?