Across
- 3. view and map Earth
- 8. representation of Earth's processes
- 10. outermost layer of atmosphere
- 12. harmful to breathe
- 14. contains all water
- 15. rocky outer layer of Earth
- 16. can be studied separately
- 17. solar wind and Earth's magnetic field
- 18. N2O
Down
- 1. second lowest layer
- 2. makes air impure
- 4. other term for biosphere
- 5. meteors burn up
- 6. a closed system
- 7. less than 220 dobson units
- 9. prolonged dry period
- 11. nearly 90% of Earth ozone
- 13. high temperature
- 14. amount of water vapor in air
- 19. invisible gas