1. Chapter 10 Section 4
CONTROLLING HEAT

2. 10.4 Controlling Heat

3. Thermal Conduction
Thermal Conduction – the process by which energy is transferred as heat through a material between two points at different temperatures.
T  E
Vibrating atoms jostle their less energetic neighbors and transfer some of their energy in the process.

4. Thermal insulators are substances that slowly transfer thermal energy.
Thermal conductors are substances that rapidly transfer thermal energy.
In general, metals
Thermal insulators are substances that slowly transfer thermal energy.
Cork, cardboard, fiberglass, gases

6. Convection and Radiation also Transfer Energy
Convection involves the displacement of hot matter in the form of a fluid by cool matter.
Natural: associated with the combined effects of pressure differences, conduction, and buoyancy.
Forced
Radiation involves the absorption or loss of electromagnetic radiation usu. in the form of infrared.

7. Examples: Natural Convection

8. Clothing and Climate Human body: 37.0°C (98.6°F)
In extreme cold environments, person can become hypothermic.
32.2°C (90.0°F), lose consciousness
Fatal at 25.6°C (78.0°F)

9. Insulating materials retain energy for cold climates
Air is an efficient insulator.
Inupiat Eskimo
Average Arctic air temperatures: 10°C (50°F) to −37°C (−35°F)
Traditional parka (atigi) made of caribou skin

10. Evaporation aids energy transfer in hot climates
Arabian Desert temperatures are often in excess of 38°C (100°F)
Heat exhaustion or heat stroke if body temperature gets too high.
Bedouin cloths
Dish-dash or dish-dasha
Kefiyah, and the mandil and a hatta
Because of the high specific heat capacity and latent heat of vaporization for water, evaporation removes a good deal of energy from the skin and air, thus causing the skin to cool.