Blair Choi's Crossword

6. The forward edge of an advancing mass of cold air that pushes under a mass of warm air; often where precipitation happens.
8. The thing that does not change.
11. Third layer of Earth's atmosphere; where meteors happen.
12. An air mass is a large body of air with generally uniform temperature and humidity.
13. The water released from the clouds.
15. The fourth layer of Earth's atmosphere; where aurora borealis happen.
16. All living organisms on Earth.
18. An energy that travels through a source.
19. Earth's last atmosphere.
20. Earth's second lowest atmosphere; where planes fly.

1. The transfer of heat or electricity through direct contact.
2. The "cause" of cause and effect.
3. The amount of water on Earth.
4. The weight of air in the atmosphere.
5. Leading edge of a mass of warm air that is advancing and replacing a cooler air mass.
7. A thing that changes for a different result.
9. A method of heat transfer.
10. The solid Earth.
14. Earth's lowest atmosphere.
17. A layer of gas that surrounds the Earth.