Heat Transfer

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Heat Transfer

• Conduction, Convection, and Radiation

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Basic Guidelines Heat and Particle Movement
Relationship
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Heat and Temperature Animated

• This simple animation shows what happens to these
  spheres (blue and yellow) when the temperature
  moves from 0 degrees Kelvin to 300 degrees
  Kelvin.
• Note the speed of the smaller (yellow) particles
  increases faster than the larger (blue) ones.

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Heat Transfer

• Heat transfer is the movement of thermal energy
  from a warmer item to a cooler item.
• Remember, heat moves in predictable ways, from a
  high to a low.

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Three Heat Transfer Situations

• Conduction
• Convection
• Radiation

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Conduction

• Conduction is heat transfer through solids.
• Examples
• Your feet transfer (conduct) heat to a cold tile
  floor
• A spoon placed in hot soup becomes warmer as the
  spoon conducts heat away from the hot soup

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Conduction examples
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Convection

• Convection occurs in fluids
• A fluid is defined as a liquid or gas because
  fluids have the ability to flow from one place to
  another
• Solids, however, maintain their position

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Convection continued

• Consider this - when you look at the road in the
  summertime on a hot day, you may notice that the
  air above the road looks blurry this is
  convection taking place as the hot air directly
  over the road absorbs the heat from the road and
  rises. Although the explanation can be quite
  complex, convection can help explain why mirages
  are seen in the desert.

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Convection and Earth Science Connection
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Radiation

• Question If conduction deals with solids and
  convection deals with liquids, how does heat
  arrive to Earth from the Sun?
• There is very little matter in between the Earth
  and Sun.

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Radiation Diagram
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Radiation continued

• Heat can travel in waves without a medium (a
  liquid, solid, or gas).
• Radiation is the term that describes heat
  movement without a medium of matter.

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The Electromagnetic Spectrum
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Radiation continued

• All of the forms of electromagnetic energy in the
  spectrum can travel through the universe as waves
  we call this radiation.

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Practical Applications

• Discuss and explain how potholes are formed
• Discuss the purpose of expansion joints on
  bridges and elevated roadways
• Describe how a hot air balloon works