Heat%20Transfer

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Heat Transfer

• Chapter 12, Section 5

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Essential QuestionsChapter 12 Section 5

1. How is temperature measured?
2. In what three ways is heat transferred?
3. How is heat transferred in the troposphere?

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Heat transfer in the troposphere plays an
important role in influencing Earths weather.
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Thermal Energy and Temperature

• Remember temperature is the average amount of
  energy of motion of each particle of a substance.
• Thermal energy is the total energy of motion in
  the particles of a substance.
• Video Overview Video Heat Temp

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Measuring Temperature

• Instrument used thermometer
• A thermometer is a thin glass tube with a bulb on
  one end that contains a liquid usually colored
  alcohol.
• How a thermometer works Liquids expand when
  heated and contract when cooled. When the
  thermometer is heated, the liquid expands and
  rises up the tube.

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Temperature Scales

• Temperature is measured in units called degrees
• Two common temperature scales are Fahrenheit and
  Celsius.
• Scientists use Celsius
• Weather reports in the U.S. use Fahrenheit
• Video

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Comparing Fahrenheit to Celsius
Degrees Fahrenheit Degrees Celsius
Freezing point of pure water 32 0
Boiling point of pure water (at sea level) 212 100
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How Heat is Transferred

• Heat is the transfer of thermal energy from a
  hotter object to a cooler one
• Three ways to transfer heat in the atmosphere
• Radiation
• Conduction
• Convection

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Radiation

• The direct transfer of energy by electromagnetic
  waves
• Example The Sun shining on your face makes your
  face feel warm

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Conduction

• The direct transfer of heat from one substance to
  another substance that it is touching
• Works well in solids but not in liquids and gases
• Metal conducts heat well
• Air and water do not conduct heat well

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Convection

• The transfer of heat by the movement of fluids
  (liquids and gases)
• Video

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Heating the Troposphere

• Radiation, conduction, and convection work
  together to heat the troposphere
• Sun shines on surface of Earth and heats it
  (radiation)
• The heated surfaces transfer heat to the air that
  is touching them. Think of the air just above a
  hot parking lot. (conduction)
• This only heats the first few meters above
  Earths surface

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In the troposphere, heat is transferred mostly by
convection.

• Convection currents are the upward movement of
  warm air and the downward movement of cool air.
  (Warm air rises, cool air sinks)
• Convection currents move heat throughout the
  troposphere

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Review Quiz
Definitions Terms
1. The temperature scale used by scientists Fahrenheit
2. An instrument used to measure air temperature Convection
3. Direct transfer of energy by electromagnetic waves Convection current
4. The total energy of motion in the particles of a substance Celsius
5. The upward and downward movement of warm and cool air that moves heat through the troposphere Temperature
6. The average amount of energy of motion of each particle of a substance Radiation
7. The temperature scale often used in the U.S. Thermometer
8. Direct transfer of heat from one substance to another substance that is touching h. Thermal energy
9. The transfer of heat by the movement of a fluid i. Conduction