Unit 2: Earth as a System

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Unit 2 Earth as a System

• Lecture 4
• The Energy Cycle

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Earths Energy Budget
99.9 of energy on Earths surface is from
sunlight
Nuclear Fusion
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Earths Energy Budget
0.013 of energy on Earths surface is from
inside the Earth
Decay of radioactive elements
Geothermal Energy
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Earths Energy Budget
0.002 of energy on Earths surface is from the
pull of the moon and sun on oceans
Tidal Energy
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What about wind energy?
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What about fire?
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What about fossil fuel?
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First Law of Thermodynamics

• Energy can not be created or destroyed, only
  converted from one form to another

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Second Law of Thermodynamics

• When energy changes form, it changes to a less
  useful form, and some will always be lost,
  usually as heat

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Albedo Energy from sun that is reflected off the
Earths surface
Low Albedo 10 reflected
High Albedo 90 reflected
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Earths Energy Budget

• If energy in energy out
• Temperature stays the same
• If energy in gt energy out
• Temperature goes up
• If energy in lt energy out
• Temperature goes down

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