Earth’s Atmosphere & Weather

1. Earth’s Atmosphere & Weather

2. Characteristics of theAtmosphere

3. 1st Atmosphere • Composition - H2, He • Lost to space early in Earth's history because: • Earth's gravity is not strong enough to hold lighter gases • Earth still did not have a differentiated core (solid inner/liquid outer core) which creates Earth's magnetic field (magnetosphere = Van Allen Belt) which deflects solar winds. • Once the core differentiated the heavier gases could be retained

4. 2nd Atmosphere • Produced by volcanic out-gassing. • H2O, CO2, SO2, CO, S2, Cl2, N2, H2 and NH3 (ammonia) and CH4 (methane) • No free O2 at this time • Ocean Formation - As the Earth cooled, H2O produced by out-gassing could exist as liquid in the early Archean, allowing oceans to form.

5. Addition of O2 • Photochemicaldissociation - breakup of water molecules by UV radiation • Produced O2 levels approx. 1-2% current levels • At these levels O3 (Ozone) can form to shield Earth surface from UV • Photosynthesis – • CO2 + H2O + sunlight  glucose + O2 • O2 produced by cyanobacteria, and eventually higher plants

6. Present Composition • 78% Nitrogen • 21% Oxygen • 1% Other trace gases

7. Layers of the Atmosphere • Caused by temp. differences • These differences result from how solar energy is absorbed as it moves through the atmosphere

8. http://www.aerospaceweb.org/question/atmosphere/atmosphere/layers.gifhttp://www.aerospaceweb.org/question/atmosphere/atmosphere/layers.gif

9. 4 Main Layers of the Atmosphere http://www.epa.gov/apti/course422/images/fig-1.gif

10. http://www.greenfacts.org/images/glossary/stratosphere-troposphere.jpghttp://www.greenfacts.org/images/glossary/stratosphere-troposphere.jpg

13. Troposphere • Closest to Earth • Nearly all weather occurs here • Almost all H2O vapor and CO2 • Temp. decreases with altitude because air in this layer is heated from below by thermal energy that is re-radiated from Earth’s surface

14. Tropopause • Upper boundary of the troposphere • Jet stream • Varies with latitude & seasons • 250 mph • East wind

15. Stratosphere • 16 – 50 km • Ozone layer is here • Temp. increases because air is heated from above by absorption of solar radiation by ozone • Jets fly here to avoid turbulence • Stratopause - upper boundary

16. Ozone Layer • Ozone is made of 3 atoms of oxygen (O3) • ≈ 2-3 mm thick if it were at sea level • Purpose - absorbs harmful UV radiation from the Sun

17. Mesosphere • 50 – 85 km • Temp. decreases as altitude increases • Mesopause - Upper boundary • AvgTemp. = - 90oC • COLDEST layer in the atmosphere • Meteors begin to disintegrate here

18. Red Sprite

19. Sprites

20. Sprites

21. Blue Jets

22. E.L.Ves.Emission of Light and Very low frequency perturbations

23. Thermosphere • 90 km ~ 1000 km • Space begins here (~100 km) • Temp. increases as altitude increases • Can’t read temp. with a thermometer because air particles are too far apart • Space Shuttle & ISS orbit here • Ionosphereis the lower region • Aurora occur here

24. Exosphere • End of the atmosphere • Almost a vacuum • Where light elements escape Earth’s gravity

26. http://curriculum.calstatela.edu/courses/builders/lessons/less/les3/les3gifs/layers.gifhttp://curriculum.calstatela.edu/courses/builders/lessons/less/les3/les3gifs/layers.gif

27. The Water Cycle

29. Temperature & Humidity

30. Temperature • A measure of the kinetic energy of the molecules of a substance

31. Methods of Heat Transfer • Conduction – direct transfer • Convection – bulk movement of particles • Radiation – electromagnetic waves

32. Where does radiation go? • 25% penetrates Earth’s atmosphere • 20% absorbed by the atmosphere • 30% scattered back into space (albedo)

33. Albedo • Varies due to • Cloud cover • Particulate matter (dust, pollen, ash, etc.) • Sun’s angle • Surface (water vs. land)

34. Differential Heating • Earth’s surface is heated unevenly due to: • Geographic position (latitude) • Land vs. Water • Altitude • Ocean currents • Cloud cover • Albedo

35. Humidity • The amount of water vapor in the air • 90% of water vapor comes from oceans (evaporation) • The warmer air is, the more water vapor it can hold

36. Dew Point • The temp. at which water vapor begins to condense • If the dew point and air temp. are the same, the following will form: • At ground level = dew or frost • Just above ground = fog • Higher levels = clouds

37. Relative Humidity • The amount of water vapor in the air expressed as a percentage of the amount required to saturate the air at the current temp. % R.H. = Actual absolute humidity x 100 Maximum absolute humidity

38. Psychrometer • Used to measure humidity • Made with 2 thermometers • Dry bulb • Measures air temp. • Wet bulb • Cooler than dry bulb • Uses evaporation to measure temp. • Wet bulb depression – difference between dry & wet bulb temps.

39. Pollution &Its Effects On the Atmosphere

40. Particulates • Tiny, solid particles • Volcanic dust • Ash f/ fires • Microscopic organisms • Mineral particles f/ the soil • Pollen f/ plants • Particles f/ meteors • Salt f/ the ocean • Can be suspended for mo’s or yrs

41. Fly ash from burning wastes http://images.google.com/imgres?imgurl=http://www.chemsoc.org/exemplarchem/entries/2002/Air%2520pollution%2520-%2520Smith%2520%26%2520Kirsop/particulates.gif&imgrefurl=http://www.chemsoc.org/exemplarchem/entries/2002/Air%2520pollution%2520-%2520Smith%2520%26%2520Kirsop/dogs16.htm&h=251&w=332&sz=62&hl=en&start=1&tbnid=jq-gUdKJKpbV4M:&tbnh=90&tbnw=119&prev=/images%3Fq%3Dparticulates%26svnum%3D10%26hl%3Den%26rls%3DTSHA,TSHA:2006-08,TSHA:en

42. Air Pollutants • Any substance that is in the atmosphere & is harmful to people, animals, plants or property • Main source is burning of fossil fuels • These release harmful substances SO2, hydrocarbons, N oxides, CO & Pb into the air

43. Pollutants http://www.greenfacts.org/images/glossary/secondary-pollutants.jpg

44. http://www.nuigalway.ie/ccaps/research_atmospheric_composition.htmlhttp://www.nuigalway.ie/ccaps/research_atmospheric_composition.html

45. http://www.windows2universe.org/earth/Atmosphere/ozone_hole.htmlhttp://www.windows2universe.org/earth/Atmosphere/ozone_hole.html

46. Breaking Down the Ozone Layer • CFC’s (chlorofluorocarbons) break down the ozone layer • They used to be used in refrigerators, air conditioners & exhaust compounds

47. www.theozonehole.com www.theozonehole.com

48. Temperature Inversions • When a layer of warm air is on top of cool air • This can trap polluted air beneath • Topography can make it worse • Smog occurs b/c of the pollutants & lack of circulation

49. Temperature Inversion http://www.epa.qld.gov.au/images/environmental_management/air/warm_air_inversion.jpg

50. http://www.virtual-lakes.co.uk/DerLatriggInversion.jpg