Lake Ice and 
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BASIC CONCEPTS: Thermal Conductivity

Heat conduction is the flow of internal energy from a region of higher temperature to one of lower temperature (temperature gradient) by the random interaction of the adjacent particles (atoms, molecules, ions, electrons, etc.) in the intervening space.

Factors affecting the rate of heat transfer by conduction are:

  • temperature difference,
  • length,
  • cross-sectional area, and
  • material.
For example, conductivities are greatest for metallic solids, lower for non-metallic solids, very low for liquids, and extremely low for gases.

Below is a table of thermal conductivity values. It includes values for the air and water, at various pressures and temperatures, and common materials used for clothing, construction and cooking.

THERMAL CONDUCTIVITY FOR SELECTED MATERIAL
(~300 K except where otherwise indicated)
Material WmK Material WmK
Vacuum 0.0 Paper 0.04-0.09
Air, sea level 0.025 Mylar 0.0001
Air, 10,000m 0.020 Glass 1.1-1.2
Water, vapor (273°K) 0.016 Straw 0.05
Water, vapor (373°K) 0.025 Particle board 0.15
Water, liquid (273°K) 0.561 Plywood 0.11
Water, liquid (373°K) 0.679 Wood 0.09-0.14
Water, ice (223°K) 2.8 Polyurethane foam 0.02-0.03
Water, ice (273°K) 2.2 Fiberglass 0.035
snow (<273°K) 0.16 Concrete 0.05-0.15
    Brick 0.18
Cotton 0.04    
Wool 0.03-0.04 Steel, stainless (273°K) 14.0
Felt 0.06 Aluminum 237.0
Feathers 0.034 Copper 401.0
Source: The Physics Hypertextbook

QUESTIONS:
Which of the clothing materials is best for winter? Why?
Which of the construction materials is best for a cold climate? Why?
Which of the cooking materials would cook a fried egg the fastest?