Ch 11

1. Ch 11 Atmosphere

2. Lesson 1 Atmospheric Basics

3. Think About It… Why would it be a bad thing if the atmosphere was mostly oxygen?

4. Focus Question… What is the composition and structure of the atmosphere?

5. Atmospheric Composition… • Nitrogen – 78% • Oxygen – 21% • Argon - .93% • Carbon Dioxide - .03% • Water Vapor - .0 to 4% • Trace Gases http://www.bbc.co.uk/schools/gcsebitesize/science/21c/atmosphere/chemicalsairrev1.shtml

6. Key Atmospheric Components • Oxygen • Gas • Living things breathe oxygen in order to break down food for energy http://schoolworkhelper.net/wp-content/uploads/2010/07/oxygen-transport.jpg

7. Key Atmospheric Components • Carbon Dioxide • Gas • Has a minor role in regulating the amount of energy the atmosphere absorbs and… • acts as a plant fertilizer http://ed101.bu.edu/StudentDoc/current/ED101fa10/ccburke/Photosynthesis.html

8. Key Atmospheric Components • Ozone • Gas • Absorbs ultraviolet radiation from the sun http://mmedia.pl/ozone-layer-diagram-for-kids

9. Key Atmospheric Components • Water Vapor • Gas • Has a major role in regulating the amount of energy the atmosphere absorbs and… • is the source of clouds, rain, and snow

10. Key Atmospheric Components • Water • Liquid • The source of rain Singing in the Rain! http://mypeartreehouse.blogspot.com/

11. Key Atmospheric Components • Ice • Solid • Makes up snow, sleet, and hail Legendary Vail Powder! http://www.austinskiers.org/trips0910/vail0910.htm

12. Key Atmospheric Components • Dust and Salt • Solids • Provide a solid surface for water vapor to condense around so that clouds can form • See next slide… Salt Spray from Waves http://www.kidsgeo.com/images/ocean-waves.jpg Dust Storm http://www.weatherfreaks.net/images/dust_storm3.jpg

13. Condensation Nuclei… http://www.sci.uidaho.edu/scripter/geog100/lect/05-atmos-water-wx/ch5-part-5-clouds-fog.htm

14. The Structure of the Atmosphere … • http://ds9.ssl.berkeley.edu/lws_gems/3/images_3/layat510.jpg

15. The Structure of the Atmosphere – The Troposphere • Description… • 0-11 km • highest air pressure • Contains most of the gases of the atmosphere • Objects Found There • Weather • life forms • jets

16. The Structure of the Atmosphere – The Stratosphere • Description… • 11-48 km • Molecular heat rises due to the ozone absorbing heat • Objects Found There • Ozone layer • Weather balloons

17. The Structure of the Atmosphere – The Mesosphere • Description… • 48-95 km • Molecular heat falls b/c there’s not a whole lot here! • Objects Found There • Meteors (shooting stars) burn here

18. The Structure of the Atmosphere – The Thermosphere • Description… • 95-550 km • Molecular heat rises • Objects Found There • Ionosphere • Auroras

19. The Auroras… http://www.lovethesepics.com/2011/02/24-amazing-auroras-aurora-borealis-aurora-australis/

20. The Structure of the Atmosphere – The Exosphere • Description… • Above 600 km • Outermost layer • Space! • Objects Found There • Some H and He • Satellites

21. Temperature Variations with Altitude http://www.aerospaceweb.org/question/atmosphere/atmosphere/layers.gif

22. What Happens to the Sun’s Energy? http://www.physicalgeography.net/fundamentals/images/cascade.GIF

23. Solar Fundamentals… a. Radiation • the transfer of energy through space by visible light, ultraviolet radiation, and other electromagnetic waves • Earth’s surface is warmed by the sun’s rays http://ossfoundation.us/projects/environment/global-warming/earths-radiation-budget

24. Solar Fundamentals… a. Conduction • the transfer of energy that occurs when molecules collide • The air molecules above Earth’s surface are warmed when they contact the warm surface of Earth

25. Solar Fundamentals… a. Convection • the transfer of energy by the flow of a heated substance • Warm air rises, then cools and sinks http://avstop.com/ac/fig5-9.jpg

26. The Transfer of Heat in the Atmosphere… Copy the diagram your teacher draws on the board!

27. Lesson 2 The State of the Atmosphere

28. Think About It… What makes a hot air balloon float?

29. Focus Question… What are the physical properties of the atmosphere that create weather?

30. Temperature of the Atmosphere… • What is temperature? • The measurement of how rapidly or slowly molecules move around • What is heat? b. The transfer of energy that occurs because of a difference in temperature between substances Heat fuels atmospheric processes!

31. The Temperature of the Atmosphere 1. The thermosphere is the hottest layer of the atmosphere but it feels so cold… because even though the molecules are moving very fast (which means they are very hot), they are so far apart that there would be no heat transfer. Astronaut Bruce McCandless II is feeling no heat! http://www.newworldencyclopedia.org/entry/Astronaut

32. The Temperature of the Atmosphere • Fahrenheit… • Boiling point … 212 • Freezing point … 32 • Absolute Zero … -523

33. The Temperature of the Atmosphere • Celsius… • Boiling point … 100 • Freezing point … 0 • Absolute Zero … -273

34. The Temperature of the Atmosphere • Kelvin… • Boiling point … 373 • Freezing point … 273 • Absolute Zero … 0 • There are NO negative numbers on the Kelvin scale!

35. Absolute Zero… Absolute zero is the temperature at which molecular motion theoretically stops! This does not occur anyplace in the universe. http://www.happynews.com/news/562009/happens-absolute-zero.htm

36. The Temperature of the Atmosphere 3a. Dew Point is the temperature to which air must be cooled at constant pressure to reach saturation. • That is when dew is formed! • The higher the dew point, more humid and uncomfortable the air. • See next slide…

37. http://www.goerie.thinkhost.com/mt/st_weather/DEW_POINT_CHART_full.JPGhttp://www.goerie.thinkhost.com/mt/st_weather/DEW_POINT_CHART_full.JPG Dew Point… Our classroom has a high dew point!

38. The Temperature of the Atmosphere 3b. Condensation is the process of water vapor changing into liquid water. It plays a role in creating rain when water vapor in the atmosphere becomes water droplets. 3c. Dew point is also called condensation temperature. (Remember the condensation nuclei?)

39. Vertical Temperature Changes • Altitude is height above ground or sea level. • Why is the temperature of the lower atmosphere cooler at higher elevations and altitudes? b. Because it is farther away from the source of heat – Earth’s surface • Individual air masses moving upward through the atmosphere will cool about 10 degrees C/1000 m.

40. Vertical Temperature Changes • What is lifted condensation level? • The height at which condensation occurs • The LCL often corresponds to the base of the clouds!

41. Air Pressure and Density… • Density is mass per volume. • As altitude increases (moving up through Earth’s atmosphere), the density of the air... … decreases • Air pressure is… … the force exerted by the molecules of the atmosphere as they are pulled toward Earth’s center. • As altitude increases… … air pressure decreases Add to notes… Air pressure is greatest in the troposphere.

42. Air Pressure and Density… 5. Air at the bottom of the atmosphere (the troposphere #6) has higher density and pressure because... … of the greater mass of the atmosphere above you! … Gravity is the force pulling all air molecules in the atmosphere toward Earth. … This is similar to being at the bottom of the ocean with tons of water above you! … We are accustomed to the high air pressure so it doesn’t squash us.

43. Temperature-Density Relationship 1a. The Relationship between Temperature and Density: Warm Air… • As temperature increases… density decreases. • Warm air is less dense and will rise. • The upward movement of warm air lowers pressure. • So, warm air rising causes low pressure.

44. Temperature-Density Relationship 1b. The Relationship between Temperature and Density: Cold Air… • As temperature decreases… density increases. • Cold air is more dense and will sink. • The downward movement of cold air raises pressure. • So, cold air sinking causes high pressure.

45. Temperature Inversion • when the upper layers of the troposphere are warmer than the lower layers. • The warmer layer is above the colder layer. • on a cold, clear, winter night, Earth’s surface cools rapidly and becomes colder than the air above it resulting in upper layer of the troposphere being warmer! • The warm layer can trap pollution or melt snow. • http://www.wrh.noaa.gov/slc/climate/TemperatureInversions.php

46. Creating Wind… • Cool air, which is denser, sinks. • This forces the warm air, which is less dense to move upwards. • Air moves from areas of high density to areas of low density. • In its simplest form, wind can be thought of as air moving from an area of high pressure to an area of low pressure. http://scifiles.larc.nasa.gov/text/kids/Problem_Board/problems/light/sim3.html

47. Humidity Changes with Temperature… • What is humidity? • The amount of water air can hold at a given temperature. This is a constant! 2. What is relative humidity? • The amount of water the air is actually holding compared to how much it can hold

48. Humidity Changes with Temperature… 3. How much water vapor can a m3 of air hold at 25 degrees C? • 24 grams 4. How much water vapor can a m3 of air hold at 15 degrees C? • 13 grams 5. Why does the air hold more water at 25 degrees than it does at 15 degrees C? • Warm air can hold more water than cold air because it is less dense. 6. How much water (per m3) would the air hold in a room at 25 degrees C if the relative humidity was 50%? • 12 grams

49. Lesson 3 Moisture in the Atmosphere

50. Think About It… Can you forecast the weather by looking at clouds?