Heat Transfer

Energy & Temperature Molecules are constantly moving Faster movement = more energy Thermal energy = total energy of motion in molecules of a substance Temperature = average amount of energy of motion of each molecule

Measuring Temperature Thermometer = used to measure temperature Works because liquids expand when heated and contract when cooled Units = degrees Water Freezes: 0°C and 32°F Water Boils: 100°C and 212°F

How Heat is Transferred Heat = energy transferred from hotter to colder object Three types: Radiation Conduction Convection

It is the direct transfer of energy by electromagnetic waves Radiation It is the direct transfer of energy by electromagnetic waves Example: feel the sun or heat from a campfire

Conduction It is the transfer of energy between substances that are touching The closer the molecules in a substance, the more effectively they can conduct heat Conductors = conduct heat well Insulators = do not conduct heat well

Convection It is the transfer of heat by the movement of a fluid Gases and liquids are fluids Molecules in gases and liquids can move from place to place and take their heat with them

Heat Transfer in the Troposphere Only first few meters heated by conduction because air does not conduct heat well Convection causes most of heating of troposphere Warm air = less dense = rises up Cooler air = more dense = sinks down Convection currents formed by rising and sinking of air