Across
- 3. the process of becoming a vapor
- 5. A biological community of interacting organisms
- 6. the weather conditions
- 13. when a gas is released into the air
- 14. a colorless odorless gas produced by burning organic compounds
- 15. gases produced by cows
- 17. the process which green plants use to grow
- 19. a radio wave longer than 1 kilometer
- 20. the daily temperatures
- 21. all the water on the earth surface
- 22. a natural fuel such as coal or gas which is millions of years old
- 23. a source of energy that is renewed
- 25. relating to a period of milder climate between two glacial periods.
- 27. red rays
- 28. a warm ocean current that flows along the equator
Down
- 1. all the parts of the earth surfaces and the earths atmosphere
- 2. Water that collects as droplets on a cold surface when humid air is in contact with it
- 4. A thick layer of soil which remains frozen throughout the year
- 7. air is made up of 78% of this
- 8. A fuel that is taken away from living matter
- 9. the land
- 10. The trapping of the sun's warmth in a planet's
- 11. the air surrounding the earth
- 12. the cycle essential for living on earth
- 16. when trees have been cleared away
- 18. the density of the ocean
- 24. a permanent layer of ice covering land
- 26. The emission of energy as electromagnetic waves