1											2
								3
		4
													5
				6	7
															8					9
10													11	12
											13
	14			15													16	17
	18								19
			20
																	21
							22
																					23	24
					25			26											27
28
															29
30
													31

Across 3. air pressure _____ as the altitude increases 4. a natural source of pollution 5. one inch of mercury is about 33.87 of these 6. envelope of gases that surrounds the planet 8. one of the acids in acid rain 10. layer where the aurora borealis occurs 11. the ozone protects us from this, which comes from the sun 15. layer where weather occurs 16. city with a lot of smog 18. layer that contains the ozone 20. gas released when fuels are burned 22. outermost layer of the atmosphere 23. this gives smoke its black color 26. dry air does not contain this 28. condition of the atmosphere at a time and place 29. force pushing on an area 30. harmful substances in the air, water, and soil 31. liquid metal used in some barometers

Down 1. another word for altitude 2. instrument used to measure air pressure 7. the layers of the atmosphere are divided based on this characteristic 9. these form when water vapor condenses 12. type of barometer with an airtight chamber 13. layer divided into two other layers 14. layer that protects us from meteroids 17. form of oxygen made of three oxygen atoms 19. all fossil fuels contain these substances 21. most common gas in the atmosphere 24. second most common gas in the atmosphere 25. as altitude increases, the _______ decreases 27. amount of mass per volume