Name:_____________________________________________________

1. How does the diameter of the Sun compare to Earth's diameter?
   
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2. What are the three factors that cause the amount of solar energy to vary over Earth's surface?
   
   
   1. ___________________________________________________________________________________________
   
   
   
   2. ___________________________________________________________________________________________
   
   
   
   3. ___________________________________________________________________________________________



3. Name a major factor that changes with the seasons.
   
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4. At 50° N latitude, how many hours of daylight are there on March 21 (see chart on frame 97)?
   
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5. What is the second major factor that changes with the seasons?
   
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6. In the summer, the angle of the Sun is     higher     or     lower     (circle one)   in the sky in the Northern Hemisphere.



7. As the Sun angle gets lower in the sky, the solar rays spread out and become: more intense    or    less intense    (circle one).



8. If the angle of the Sun is at 30° above the horizon, how many equivalent number of atmospheres must sunlight pass
   
   through (see chart on frame 113)?
   
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9. Why are many of Earth's plants in a dormant state during the winter?
   
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