Shelter, clothing, and fire

How heat moves

Conduction:

• What it is: Heat moving directly from one solid object to another by touching, like standing barefoot on a cold floor.
• How to manage it: In the cold, put an insulating pad or layer between your sleeping bag and the ground so the cold earth doesn't drain your body heat.

Convection: 

• What it is: Heat being carried away by air or water currents, like wind chill.
• How to manage it: In the cold, wear windproof clothing or build a shelter that blocks the wind. In the heat, use a fan or breeze to cool off.

Radiation: 

• What it is: Heat emission, like feeling the heat from a campfire or the sun. You don't have to touch it.
• How to manage it: In the cold, wear thick clothing to hold heat in or use a reflective blanket to bounce your body heat back to you.

Metabolism: 

• What it is: Converting food into energy and heat. Food is your body’s source of fuel.
• How to manage it: Eat high-calorie snacks (like energy bars or trail mix) in cold weather to keep your body burning fuel. Drink plenty of water, but avoid alcohol and caffeine—they trick your brain into feeling warm while actually speeding up heat loss.

Evaporation:

• What it is: Changing liquid into gas takes heat energy and cools things down, like sweat drying on your skin.
• How to manage it: In the heat, stay hydrated so you can sweat and cool off. In the cold, stay dry and avoid sweating so you don't freeze. Never wear cotton in the cold, as it holds moisture against your skin.

Managing heat

After learning how your body gains or losses heat, it is important to learn how to prevent or promote those heat losses and gains.

Insulation: 

• What it is: Trapping air to slow down heat movement, like wearing a coat in cold weather.
• How to manage it: Air is not a good heat conductor, so it works well as a barrier. Multiple small layers of clothing trap air for insulation and allow you to regulate to a comfortable temperature by adding or removing layers as needed. Insulation prevents conduction and radiation.

Reflection: 

• What it is: Bouncing heat toward or away from you, like when using a Mylar reflective blanket.
• How to manage it: Heat can be deflected and directed just like a flashlight beam and a mirror. Reflect your radiated body heat back to you in cold weather. In hot weather, reflect the sun's heat away from you. These can both be done by using reflective Mylar blankets. If used properly, Mylar blankets can reflect 90% of your body's heat back to you.

Protection: 

• What it is: Keeping out of the sun, rain, wind, and physical dangers.
• How to manage it: Protect yourself from the elements. Wear a waterproof outer shell to stay warm and dry when it's cold. Wear a wide brimmed hat, light colored clothing, and sunscreen when it's hot. Put up a shelter that offers shade and blocks wind and rain.

Moisture wicking: 

• What it is: Pulling water away from the body.
• How to manage it: Wool or an artificial fiber clothing like polyester, fleece, and nylon can actually pull moisture away from your skin. You do not want evaporation happening on your skin when you are cold. DO NOT wear cotton in cold weather situations since cotton holds wetness and causes evaporation next to your skin.