There are five ways you lose body heat to the environment.Take measures to protect yourself from the elements.

Losing body heat means you can no longer thermoregulate and are at risk of dying from hypothermia. It’s important to know these fiveways are, and take steps to prevent them.

The five ways that we lose body heat are:

  • Radiation
  • Respiration
  • Evaporation
  • Conduction
  • Convection

Radiation

This is happening all the time, because heat is going to move along a temperature gradient from an area of a higher temperature to an area of a lower temperature, attempting to reach an equilibrium. Radiation will happen when a 98.6- degree body is in a 70-degree environment. We constantly lose heat into the atmosphere. Clothing and sleeping bag system matters. Insulating layers trap some radiated heat and keep you warm.

Respiration

When you inhale air, your airway must warm that air and bring it to the same temperature as the rest of your body. Cold air coming in is taking heat away from your respiratory system, and then of course every time you exhale you’re exhaling that warm air out into the environment. There’s not much you can do about it. In very cold environments, you can throw a scarf over your mouth/nose to trap some warmer air.

Evaporation

Basically involves sweating. When you sweat, it evaporates, and takes body heat with it. We tell everyone, “if you sweat, you die” in a survival situation. Never allow yourself to sweat. Always dress in loose layers, keep your clothing dry, and avoid overheating. Conduction and convection are two heat loss processes you can do the most to avoid:

Conduction

When your body is physically touching something that’s colder (the ground) that colder surface pulls heat continuously from your warmer body. Heat is trying to move down the temperature gradient. Ground insulation is one of the key things that will help you to avoid losing heat.

Convection

This involves current flowing across your body. There are two different types, and the one that we’re most concerned with is wind. Imagine a lesser temperature wind blowing across your warmer body. As it blows, the heat from your body is constantly trying to warm that air. Water currents are another form of convection. When you’re doing a stream crossing, that colder water flowing around your body (like the wind), steals heat as it moves. Wear insulating clothing and a windproof, waterproof layer.

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