AWH 5-6

Chapter 5, Heat and Temperature 5-6 Figure 5-4. Solar Zenith Angle 5.6.2 Conduction Conduction is the transfer of energy (including heat) by molecular activity from one substance to another in contact with or through a substance. Heat always flows from the warmer substance to the colder substance. The rate of heat transfer is greater with larger temperature differences and depends directly on the ability of the substance(s) to conduct heat. During conduction, the warmer substance cools and loses heat energy, while the cooler substance warms and gains heat energy. Heat (thermal) conductivity is the property of a substance that indicates its ability to conduct heat as a consequence of molecular motion. Units are watts per meter-kelvin (W m-1 K-1). Table 5-3 provides the heat (thermal) conductivity of various substances. Note that air is a poor thermal conductor.