Across
- 4. ______sphere
- 5. type of non-renewable fuel
- 8. what we breathe
- 10. all of the layers of air
- 14. _________ dioxide
- 15. warming effect
- 16. animal that makes methane
- 17. light that heats
- 20. landfill gas
- 21. air __________ index
- 22. energy from the sun
Down
- 1. first layer of the atmosphere
- 2. energy from plants
- 3. energy found along Egypt's coasts
- 6. nitrous _________
- 7. ________synthesis
- 9. energy from the heat of the earth
- 11. gas we need to survive
- 12. these release nitrous oxide
- 13. main gas in atmosphere
- 18. hydroelectric city in Egypt
- 19. abbreviation for extraterrestrial