- How can there be clouds in winter when it is too cold for water to stay a vapor?
- How do plants get their nitrogen from the air?
- How do trees give earth all its oxygen?
- How does a cloud fill up with water?
- What makes meteorites so hot that you can't touch them?
- What makes the Sahara the largest desert in the world?
- Why don't I feel the miles of air above me that are crushing me down?