P:1 2020 Khan

1. breathing polluted air for long periods of time can cause more serious problems
7. driven by human emissions of greenhouse gases, and the resulting large-scale shifts in weather patterns
10. the third-most abundant gas in the Earth's atmosphere
12. this layer absorbs a lot of the UV radiation and X-ray given off by the sun
15. accounted for about 6.5 percent of all U.S. greenhouse gas emissions
18. the permanent removal of trees to make room for something besides forest
19. the most dangerous and prevalent greenhouse gas
20. forms about 78 percent of the earth's atmosphere
21. 90% of the ozone layer is found in the spheres upper crust
22. in this layer, temperature decreases as altitude increases
24. forms about 21 percent of the earth's atmosphere
25. the lowest layer of Earth's atmosphere

2. the temperature of something raising higher than normal
3. Radiatively active gases (i.e., greenhouse gases) in a planet's atmosphere radiate energy in all directions.
4. the process by which a natural habitat becomes incapable of supporting its native species
5. any of several simple gaseous compounds that contain carbon, chlorine, fluorine, and sometimes hydrogen
6. a rare gas that is found in the Earth's atmosphere
8. the condition of being populated with excessively large numbers
9. the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without this atmosphere
11. the earth's atmosphere that contains a high concentration of ions and free electrons and is able to reflect radio waves
13. the presence in or introduction into the environment of a substance or thing that has harmful or poisonous effects
14. this gas is about 28 times more powerful than carbon dioxide at warming the Earth
16. the wearing away of a field's topsoil by the natural physical forces of water
17. the largest contributor to the Earth's greenhouse effect
23. this layer is the highest and top layer of the Earth's atmosphere