chapter 4

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Across
  1. 1. The regions of Earth where life exists.
  2. 7. A system where outputs affect inputs, either amplifying or reducing changes.
  3. 9. The gaseous envelope surrounding Earth.
  4. 10. Angular distance east or west of the prime meridian.
  5. 13. Angular distance north or south of the equator.
  6. 15. The point in Earth's orbit when it is closest to the Sun.
Down
  1. 2. The shape of Earth, which is slightly flattened at the poles.
  2. 3. All the water on Earth's surface, including oceans, lakes, and rivers.
  3. 4. The rigid outer layer of Earth, including the crust and upper mantle.
  4. 5. A line of latitude circling Earth parallel to the equator.
  5. 6. The frozen water part of Earth's system.
  6. 8. The movement of Earth around the Sun, taking about one year.
  7. 11. The latitude line at 0 degrees.
  8. 12. Planets closer to the Sun, smaller and rockier than outer planets.
  9. 14. Outer planets made mostly of gas and much larger than inner planets.