HOW THE BODY LOSES HEAT

American Survival Guide - - GEAR GUIDE -

The body loses heat in sev­eral ways, and the four el­e­ments of “COLD” ad­dress these ar­eas in their own way. The four main mech­a­nisms of heat loss are—

Evap­o­ra­tion. The body’s way of re­duc­ing its in­ter­nal tem­per­a­ture is to per­spire. Sweat glands take wa­ter from the blood to pro­duce the sweat. At the same time, it moves the heat of the blood to the sur­face of the skin, where it evap­o­rates, re­duc­ing body heat in two ways. The first method is by re­duc­ing the amount of heat in the blood, and the sec­ond method is by cool­ing the skin through evap­o­ra­tion.

Ra­di­a­tion. Be­cause na­ture al­ways tries to cre­ate a bal­ance, if body tem­per­a­ture is higher than the air around it, the body will ra­di­ate its heat into the air. The greater the dif­fer­ence be­tween body tem­per­a­ture and air tem­per­a­ture, the more heat is lost to the air.

Con­duc­tion. Heat moves from a hot­ter area to a colder area, and it moves through what­ever is there to serve as a con­duc­tor. Air is the poor­est con­duc­tor, be­cause it isn’t very dense. Solids such as rock or dirt are the best con­duc­tors, be­cause they are very dense and ho­mo­ge­neous. Wa­ter or mois­ture are mod­er­ate-level con­duc­tors but are the most com­mon when outdoors. Keep­ing your body and cloth­ing dry will help in­hibit this move­ment of heat out of your body.

Con­vec­tion. Your body heats the air around it through con­duc­tion, as de­scribed above. But if that warm air is pushed away from your body by a breeze or other ac­tion, your body will heat it again and again, un­til what­ever is mov­ing it away from the body stops. The loss of heat by mov­ing the warm air is called “con­vec­tion.” A com­mon ex­am­ple of this is wind blow­ing across your body. This cool­ing of the body is called “wind chill.”

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