Ch. 1 & 3 Crossword

2. the transfer of energy across space and in the atmosphere
4. atmospheric layer nearest to Earth's surface
6. the condition in which human needs are met in such a way that a human population can survive indefinitely
9. the practice of growing, breeding, and caring for plants and animals that are used for food
10. shows the productive area of Earth needed to support one person in a particular country
15. above the troposphere; extends 18 km
17. the continuous movement of water into the air, onto land, and then back to water sources
19. an undesired change in air, water, or soil that adversely affects the health, survival, or activities of humans or other organisms
20. the study of how living things interact with each other

1. process by which liquid water is heated by the sun and then rises into the atmosphere as water vapor
3. process in which gases trap heat near the Earth
5. a natural material that is used by humans
7. mixture of gases surrounding the Earth
8. refers to the number and variety of species that live in an area
11. water vapor forms water droplets on dust particles
12. a little more than 2 percent of all the water on Earth
13. divided piece(s) of the rigid, outermost layer of the Earth
14. innermost layer of the earth
16. the narrow layer around Earth's surface in which life can exist
18. the removal and transport of surface material