AWH 5-7

Chapter 5, Heat and Temperature 5-7 Table 5-3. Heat (Thermal) Conductivity of Various Substances Material Phase Heat (Thermal) Conductivity (W m-1 K-1) Silver Solid 429 Copper Solid 401 Aluminum Solid 250 Iron Solid 80 Sand (saturated) Solid 2.7 Water (ice) Solid (0 °C) 2.18 Sandstone Solid 1.7 Limestone Solid 1.26–1.33 Glass Solid 1.05 Water (liquid) Liquid 0.58 Sand (dry) Solid 0.35 Soil Solid 0.17–1.13 Wood (oak) Solid 0.17 Wood (balsa) Solid 0.055 Snow Solid (<0 °C) 0.05–0.25 Air Gas 0.024 Water (steam) Gas (125 °C) 0.016 All measurements are at 25 °C unless otherwise noted. Note: 1 K equals -272.15 °C. 5.6.3 Convection Convection is the transport of heat within a fluid, such as air or water, via motions of the fluid itself. This type of heat flow takes place in liquids and gases because they can move freely and it is possible to set up currents within them. Water boiling in a pot is an example of convection. Because air is a poor thermal conductor, convection plays a vital role in the Earth’s atmospheric heat transfer process. Figure 5-5 illustrates examples of various heat transfer processes.