Transferring Heat

The body cools itself using one of the following methods to transfer heat:

• Evaporation (sweating). This method is important when the air is warmer than 68°F (20°C). Evaporation during strenuous exercise helps the body lose most of the excess heat produced by the activity. Sweating is not as effective in a humid environment. Sweat that drips off the body does not transfer as much heat away from the body as sweat that evaporates from the skin.
• Radiation (similar to heat leaving a woodstove). This occurs when the air temperature is lower than body temperature. Radiation helps cool the body but is less effective when the air is warmer.
• Conduction (such as sleeping on cold ground or swimming in cool water). Cool air does not help the body cool very quickly. But the body can quickly lose heat when it is exposed to cool water.
• Convection (such as sitting in front of a fan or standing in the wind). Convection helps cool the body but is less effective when the air is warmer.