1. The Atmosphere Table of Contents The Air Around You Air Pressure Layers of the Atmosphere Air Quality

2. The Atmosphere Composition of the Atmosphere Weather – the condition of Earth’s atmosphere at a particular time and place. Atmosphere – the envelope of gases that surrounds Earth. - The Air Around You

3. The Atmosphere - The Air Around You Composition of the Atmosphere Earth’s atmosphere is made up of nitrogen, oxygen, carbon dioxide, water vapor, and many other gases, as well as particles of liquids and solids.

4. The Atmosphere Composition of the Atmosphere The dry part of the atmosphere is made up of: – 78% Nitrogen – 21% Oxygen – (mostly O 2, but some of which is in the form of ozone O 3 ) – 0.038% Carbon Dioxide – 0.93% Argon – Trace amounts of Helium, Neon, Methane, Krypton, and Hydrogen - The Air Around You

5. The Atmosphere Oxygen Click the Video button to watch a movie about oxygen. - The Air Around You

6. The Atmosphere Composition of the Atmosphere Water vapor is also found in the atmosphere and plays an important role in Earth’s weather – Water vapor – water in the form of a gas. – Condenses to form clouds or even rain/snow Particles – also found in the atmosphere – tiny solid and liquid particles of dust, smoke, salt, and other chemicals - The Air Around You

7. The Atmosphere Importance of the Atmosphere Earth’s atmosphere makes conditions on Earth suitable for living things. – Contains oxygen and carbon dioxide for organisms – Traps energy from the sun, warming the planet – Provides moisture for organisms – Protects the planet from meteors and other space rocks - The Air Around You

8. The Atmosphere Links on the Atmosphere Click the SciLinks button for links on the atmosphere. - The Air Around You

9. The Atmosphere Properties of Air Because air has mass, it also has other properties, including density and pressure – Density – the amount of mass of a substance in a given volume. – Pressure – the amount of force pushing on an area. Air pressure – the pressure caused by the weight of a column of air pushing down on an area. - Air Pressure

10. The Atmosphere Properties of Air There is a column of air above you all the time. The weight of the air in the atmosphere causes air pressure. - Air Pressure

11. The Atmosphere Measuring Air Pressure Barometer – an instrument used to measure changes in air pressure. – Two common kinds include: Mercury barometer – an instrument that measures changes in air pressure, consisting of a glass tube partially filled with mercury, with its open end resting in a dish of mercury. – As air pressure increases, it presses down more on the surface of the mercury. – Increased air pressure forces the column of mercury higher – Ave. pressure at sea level is 76 centimeters high - Air Pressure

12. The Atmosphere - Air Pressure Measuring Air Pressure Air pressure pushes down on the surface of the mercury in the dish, causing the mercury in the tube to rise. The air pressure is greater on the barometer on the right, so the mercury is higher in the tube.

13. The Atmosphere Measuring Air Pressure Aneroid barometer – an instrument that measures changes in air pressure without using a liquid. – Has airtight metal chamber connected to springs and a gauge. – As air pressure increases the thin walls of the chamber are pushed in, when it decreases they bulge. – Common “household” tool - Air Pressure

14. The Atmosphere - Air Pressure Measuring Air Pressure This diagram shows an aneroid barometer. Changes in air pressure cause the walls of the airtight metal chamber to flex in and out. The needle on the dial indicates the air pressure.

15. The Atmosphere Measuring Air Pressure Activity Click the Active Art button to open a browser window and access Active Art about measuring air pressure. - Air Pressure

16. The Atmosphere - Air Pressure Air Pressure and Altitude Air pressure decreases as altitude increases.

17. The Atmosphere - Air Pressure Altitude and Density The density of air decreases as altitude increases. Air at sea level has more gas molecules in each cubic meter than air at the top of a mountain.

18. The Atmosphere - Layers of the Atmosphere Layers of the Atmosphere The atmosphere is divided into four main layers: – Troposphere – Stratosphere – Mesosphere – Thermosphere Further divided into: – Ionosphere – Exosphere

19. The Atmosphere The Troposphere Troposphere - the lowest layer of the atmosphere in which Earth’s weather occurs. – Tropo- means “turning” or “changing.” – Rises 9-16 km above the earth’s surface (5 ½ -10 mi) – Temperature drops in the troposphere on average 6.5°C for every 1 km of altitude. - Layers of the Atmosphere

20. The Atmosphere The Stratosphere Stratosphere – is the second layer of the atmosphere and contains the ozone layer. – Extends from 16 km up to 50 km above the earth’s surface (10-31 miles) – The upper portion of the stratosphere is warmer than the lower portion This is due to ozone (O 3 ) blocking out many UV rays to the lower layers. - Layers of the Atmosphere

21. The Atmosphere The Mesosphere Mesosphere – layer of Earth’s atmosphere immediately above the stratosphere. – “Meso” means middle – Extends from 50 km to 80 km above the earth’s surface (31-50 miles) – Temperatures in the outer mesosphere drop to -90°C (-130°F) – The mesosphere is the layer of the atmosphere that protects Earth’s surface from being hit by most meteoroids. - Layers of the Atmosphere

22. The Atmosphere The Thermosphere Thermosphere – the outermost layer of Earth’s atmosphere. – Extends from 80km into space with no definite outer boundary. – Gas molecules in this layer are heated by the direct rays of the sun and travel at high speeds making them hot (1,800°C), but the air is so thin (few molecules) it would feel extremely cold because the molecules are so far apart.

23. The Atmosphere The Thermosphere Ionosphere - the lower part of the thermosphere. – Extends 80-400km – Contains gas ions (electrically charged particles) that were charged by the suns energy Exosphere - the outer layer of the thermosphere. – 400 km to thousands of km

24. The Atmosphere Changing Temperatures The graph shows how temperatures in the atmosphere change with altitude. Use it to answer the questions that follow. - Layers of the Atmosphere

25. The Atmosphere Changing Temperatures Reading Graphs: What two variables are being graphed? In what unit is each measured? Temperature and altitude; degrees Celsius and kilometers - Layers of the Atmosphere

26. The Atmosphere Changing Temperatures Reading Graphs: What is the temperature at the bottom of the stratosphere? Approximately –55ºC - Layers of the Atmosphere

27. The Atmosphere Changing Temperatures Interpreting Data: Which layer of the atmosphere has the lowest temperature? The thermosphere - Layers of the Atmosphere

28. The Atmosphere Changing Temperatures Making Generalizations: Describe how temperature changes as altitude increases in the troposphere. Temperature decreases as altitude increases. - Layers of the Atmosphere

29. The Atmosphere More on the Ozone Layer Click the Planet Diary button for an activity about the ozone layer. - Layers of the Atmosphere

30. The Atmosphere Air Quality Pollutants - harmful substances in air, water, or soil. Air pollution can cause many different problems. This table shows the health effects of air pollution. Pollen also can cause difficulties for people with allergies. - Air Quality

31. The Atmosphere Sources of Pollution Natural Sources include: – Forest fires, soil erosion, dust storms, pollen, mold, and volcanic ash, dust, and gases Human Activities include: – Farming, construction, and burning fossil fuels – Almost half of these come from motor vehicles, – Power plants and factories also burn fossil fuels - Air Quality

32. The Atmosphere Smog and Acid Rain The burning of fossil fuels can cause smog and acid rain. – Smog – word created in the early 1900’s to combine “smoke” and “fog” London-type smog - forms when particles in coal smoke combine with water droplets in humid air. – Named after the thick layer of pollutants that filled the air in London during the industrial revolution. - Air Quality

33. The Atmosphere Smog and Acid Rain Photochemical Smog - a brownish haze that is a mixture of ozone and other chemicals, formed when pollutants react with each other in the presence of sunlight. – Common in large cities like Los Angeles - Air Quality

34. The Atmosphere Smog and Acid Rain Acid rain – rain that contains a lower pH than normal. – Results when sulfur oxides and nitrogen oxides (released from the burning of fossil fuel) combine with water vapor in the atmosphere – sometimes strong enough to damage the surfaces of buildings and statues – can make water so acidic that plants, amphibians, fish, and insects can no longer survive in it - Air Quality

35. The Atmosphere More on Air Pollution Click the PHSchool.com button for an activity about air pollution. - Air Quality

36. The Atmosphere Data Sharing Lab Click the PHSchool.com button for an activity to share data from the Design Your Own Lab How Clean Is the Air? - Air Quality

37. The Atmosphere Improving Air Quality In the United States, the federal and state governments have passed a number of laws and regulations to reduce air pollution. – The Environmental Protection Agency (EPA) monitors air pollutants in the United States – Newer cars have helped improve air quality in the past 30 years, but more people mean more cars and factories. - Air Quality

38. The Atmosphere More on Cars and Clean Air Click the PHSchool.com button for an activity about cars and clean air. - Air Quality

39. The Atmosphere Graphic Organizer increases Air Pressure decreases as measured in units of measured with Density decreases Altitude Millibars Aneroid include Inches of mercury Barometers Mercury