1. The Atmosphere

2. What is weather? state of the atmosphere at a given time and place

3. Who studies the weather? Meteorologists – scientists Meteorology – study of the atmosphere and related phenomena WGN Chicago Tom Skilling NBC Chicago Ginger Zee

4. Look at the following pictures. Think about how these pictures relate to Earth’s dynamic atmosphere.

11. How did Earth’s atmosphere form? Volcanoes (Nitrogen, Sulfur, CO, CO 2, CH 4 ) Comets (H 2 O) Photosynthesis (O 2 )

12. Composition of the Atmosphere Lower atmosphere 99% of atmosphere in the lowermost 32 km99% of atmosphere in the lowermost 32 km Upper atmosphere ~vacuum (low air pressure)~vacuum (low air pressure) composition changescomposition changes oxygen layer  helium layer  hydrogen layer  outer spaceoxygen layer  helium layer  hydrogen layer  outer space

13. Earth’s layered atmosphere based on temperature and composition differencesbased on temperature and composition differences

14. ozone absorbs energy in stratosphere ~ 70% atmosphere in troposphere Temperature changes with altitude

15. Our atmosphere is very thin compared to the size of Earth.

16. Troposphere composition ppmv: parts per million by volume GasVolume Nitrogen (N 2 )78.084% Oxygen (O 2 )20.946% Argon (Ar)0.9340% Carbon dioxide (CO 2 )365 ppmv Neon (Ne)18.18 ppmv Helium (He)5.24 ppmv Methane (CH 4 )1.745 ppmv Krypton (Kr)1.14 ppmv Hydrogen (H 2 )0.55 ppmv Not included in above dry atmosphere: Water vapor (highly variable)typically 1%

17. The ionosphere layers in mesosphere & thermosphere containing ionslayers in mesosphere & thermosphere containing ions affects travel of radio wavesaffects travel of radio waves –radio travels farther at night auroras = solar particles interacting with the ionosphereauroras = solar particles interacting with the ionosphere

18. ionosphere affects radio wavesaffects radio waves influences aurorasinfluences auroras

19. Auroras ions interacting with atmospheric gases and solar particles

20. radio waves travel farther at night

21. Earth’s Heat Budget insolation (incoming solar radiation)insolation (incoming solar radiation) most of atmosphere’s energy transferred from the surfacemost of atmosphere’s energy transferred from the surface –radiation (infrared) absorbed by carbon dioxide and water vapor (greenhouse effect)absorbed by carbon dioxide and water vapor (greenhouse effect) –conduction and convection –evaporation of water

23. Earth’s heat budget

24. Human activity can affect Earth’s heat budget.

25. Chemical and transport processes related to atmospheric composition

26. Causes of Local temperature variations Intensity of insolationIntensity of insolation –incoming solar radiation from the Sun Time of DayTime of Day –morning vs. noon LatitudeLatitude –Equator vs. Poles Time of YearTime of Year –winter vs. summer Cloud CoverCloud Cover –clouds trap heat Differential heatingDifferential heating –land vs. water vs. snow

27. Intensity of Insolation varies with: 1.Time of Day More direct/vertical radiation (closer to 90 ˚) = more intense At noon, the sun’s rays are closest to 90 ˚ However, warmest time of day is usually around 3:00 PM Coolest time of day usually right before sunrise

28. 2.Latitude Angle of sunlight varies with latitude Equator receives almost vertical rays year round – HOT Poles receive sun’s rays at low angles - COLD

29. 3.Time of Year More direct rays – warmer; usually warmer a month after maximum insolation Example: Here it is warmest in July & maximum insolation is in June (summer solstice) Least direct rays – cooler a month after; January is our coolest month; December is time of minimum insolation

30. 4. Cloud cover Clouds reflect sunlight; warmer on a clear day Clouds hold in heat; warmer on a cloudy night

31. Surfaces heat up more if the Sun is more directly overhead SummerWinter

32. Sun rays strike Earth from 0° to 90°

33. More atmosphere to go through reflects more light

34. Insolation varies with latitude and time of year

35. Temperatures of land vary more than water due to land’s low specific heat

36. Temperature Maps Isotherms Isotherms Isotherms Lines drawn on weather map to show places with the same temperature One isotherm line represents 5 - 10 ˚ Lines are not straight because land and water heat and cool differently

39. Are more regular in the Southern Hemisphere because mostly water Bend toward poles in a warmer area Bend toward equator in a colder area In Northern Hemisphere shift: *Northward in July *Southward in January

40. Isotherms = equal temperature lines Complex patterns based on land cover and elevation

42. Human Impacts on the Atmosphere ParticulatesParticulates –smoke, dust, and ash Acid rainAcid rain –sulfur and nitrogen emissions SmogSmog –automobile exhaust Ozone depletionOzone depletion –CFC emissions Global warmingGlobal warming –greenhouse gases like CO 2 and CH 4

43. Temperature Inversions The troposphere usually cools with increasing altitudeThe troposphere usually cools with increasing altitude Inversion = layer of air near the ground where temperature increases with increasing altitudeInversion = layer of air near the ground where temperature increases with increasing altitude –usually forms early in the morning after a clear night.

44. Los Angeles, CA temperature inversions keep smog near the groundtemperature inversions keep smog near the ground

45. The Ozone “Hole” is carefully monitored by scientists It is not really a hole…just a region of lower ozone concentration Ozone blocks UV lightOzone blocks UV light CFCs destroy ozoneCFCs destroy ozone CFCs remain in the atmosphere for yearsCFCs remain in the atmosphere for years

46. The ozone hole is the region over Antarctica with total ozone of 220 Dobson Units or lower. This map shows the ozone hole on October 4, 2004. The data were acquired by the Ozone Monitoring Instrument on NASA’s Aura satellite.Ozone Monitoring Instrument Aura

47. Largest Recorded Ozone Hole September 2006 26 million km 2

49. What if the world never stopped using CFCs? simluation showing the size of the ozone hole by 2054simluation showing the size of the ozone hole by 2054 global ozone drops by halfglobal ozone drops by half short wavelenght skin cancer- causing radiation hundreds to thousands of time as intenseshort wavelenght skin cancer- causing radiation hundreds to thousands of time as intense Internet Link Red = high concentrations Blue = low concentrations

50. Greenhouse Effect certain gases absorb outgoing infrared radiation and heat the atmospherecertain gases absorb outgoing infrared radiation and heat the atmosphere Without the Greenhouse Effect Earth would be ~ 60° F cooler

51. Greenhouses (analogy) heats up because the Sun warms the ground inside itheats up because the Sun warms the ground inside it ground warms the air near the groundground warms the air near the ground air is prevented from rising and flowing away.air is prevented from rising and flowing away. warming thus occurs by suppressing convectionwarming thus occurs by suppressing convection Cooler Hotter

52. Greenhouse Gases Naturally occurring:Naturally occurring: –water vapor –carbon dioxide –ozone –methane –nitrous oxide Human emissions:Human emissions: –carbon dioxide –methane (livestock) –CFCs (chlorofluorocarbons) –HCFCs –HCFCs (hydrochlorofluorocarbons) –HFCs (hydrofluorocarbons)

56. Yearly fluctuation due to seasonal plant growth (Northern Hemisphere) Long-term increases in CO 2 most likely caused by human emissions

57. Humans are rapidly adding to the level of greenhouse gases! power-plants livestock deforestation transportation

58. Consumer decisions that you make can help to reduce greenhouse gas emissions. Website – Carbon offset Carbon offsetCarbon offset

59. Hybrid vehicle fuel economy gauges help you drive more efficiently

60. Consumer can also offset fossil fuel electricity use with renewable energy certicicates

61. The future? Can humans use natural resources in a sustainable manner, minimize the warming of the atmosphere, and prevent likely outcomes of global warming? Tropical diseases increase Sea levels rise as glaciers melt Species endangered or extinct