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GEOG 1306 – Class 1

GEOG 1306 – Class 1. 1.1 Essentials of Geography Maps 1.2 Solar Energy and The Seasons. Solar Energy to Earth and the Seasons. The Solar System, Sun, and Earth   Solar Energy: From Sun to Earth   The Seasons . ENERGY IN THE EARTH-ATMOSPHERE SYSTEM.

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GEOG 1306 – Class 1

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  1. GEOG 1306 – Class 1 1.1 Essentials of Geography Maps 1.2 Solar Energy and The Seasons

  2. Solar Energy to Earth and the Seasons • The Solar System, Sun, and Earth   • Solar Energy: From Sun to Earth   • The Seasons 

  3. ENERGY IN THEEARTH-ATMOSPHERE SYSTEM Non-uniform energy receipt leads to: • patterns of heating & cooling • motion of atmosphere & oceans Solar Radiation Enters via Earth’s Atmosphere

  4. Weather & Climate Accomplish Energy Balances • for the Earth-atmosphere system • for the earth surface & atmosphere sub-systems

  5. The Solar System, Sun, and Earth   • Solar system formation and structure   • Gravity • Planetesimal hypothesis • Dimensions and distances • Speed of light • Earth’s orbit

  6. Solar System Formation and Structure   • Gravity • Mutual attracting force exerted by mass on all other objects • Planetesimal hypothesis • Suns condense from nebular clouds

  7. Milky Way Galaxy Figure 2.1

  8. Dimensions and Distances • Speed of light • 299,792 kmps (186,282 mps) • Milky Way Galaxy 100,000 ly across • Our Solar System 11 light-hours across • Moon is 1.28 light-seconds away

  9. DISTANCES • On Earth: 1 mile = 1.6 km 1 km = 1,000m = 0.6 mi • Astronomical Unit (AU) Average Earth-Sun distance = 150M km

  10. Dimensions and Distances • Earth’s orbit • Average distance from Earth to the Sun is 150,000,000 km (93,000,000 mi) • Perihelion – closest at January 3 • 147,255,000 km (91,500,000 mi) • Aphelion – farthest at July 4 • 152,083,000 km (94,500,000 mi) • Earth is 8 minutes 20 seconds from the Sun • Plane of Earth’s orbit is the plane of the ecliptic

  11. Ellipse Focus 2 foci

  12. Our Solar System Figure 2.1

  13. Aphelion Perihelion

  14. Solar Energy: From Sun to Earth   • Solar activity and solar wind   • Electromagnetic spectrum of radiant energy • Intercepted energy at the top of the atmosphere 

  15. Solar Activity and Solar Wind • Solar wind is a stream of electrically charged particles • Sunspots are caused by magnetic storms • Sunspots have activity cycle of 11 years Figure 2.2

  16. SOLAR ENERGY Sun captured 99.9% of matter in solar nebula  nuclear fusion Solar Outputs: 1) Solar wind 2) Electromagnetic radiation • speed of light in all directions • Earth intercepts 1/2x109 of incoming solar radiation in sol ation

  17. Monthly Average Number of Sunspots

  18. Aurora Borealis Figure 2.4

  19. The Electromagnetic Spectrum • Sun radiates shortwave energy • Shorter wavelengths have higher energy • Earth radiates longwave energy

  20. Wavelength and Frequency Figure 2.5

  21. The Electromagnetic Spectrum Figure 2.6

  22. ENERGY AT THE THERMOPAUSE 1) Intensity 2) Wavelength of Peak Emission 3) Distribution by Place & Time

  23. ENERGY AT THE THERMOPAUSE 1) Intensity Stefan-Boltzmann Law: E =  T4 Sun surface: 6,000C … Earth Surface: 15C Solar Constant = 1372 W/m2 = 2 calories/cm2/min

  24. Insolation Terrestrial Radiation

  25. Solar and Terrestrial Energy Figure 2.7

  26. Earth’s Energy Budget Figure 2.8

  27. 2) Distribution by Wavelength Wien’s Law:  = k/T Insolation max’m at: 0.5 microns (µm) … Visible Terrestrial radiation max’m at: 10 µm … IR Greenhouse Effect

  28. 3) Distribution of Insolation by Place & Time

  29. Average Daily Net Radiation

  30. Sun Angle increases Intensity Day Length increases Total Received Sun Angle & Day Length vary with: • Latitude • Time of Year

  31. Distribution of Insolation • Tropics receive more concentrated insolation due to the Earth’s curvature • Tropics receive 2.5X more than poles

  32. The Seasons   • Seasonality   • Reasons for seasons   • Annual march of the seasons  

  33. Insolation at Top of Atmosphere 1372 W/m2 = solar constant Average value of insolation at thermopause at average Sun-Earth distance Figure 2.10

  34. Seasonality • Seasonal changes • Sun’s altitude – angle above horizon • Declination – location of the subsolar point • Daylength

  35. Daily Net Radiation Figure 2.11

  36. Reasons for Seasons  • Revolution • Rotation • Tilt of Earth’s axis • Axial parallelism • Sphericity

  37. THE SEASONS 1)Parallel Rays 2) Diurnal ROTATION 3) Annual REVOLUTION (orbit)

  38. Reasons for Seasons  • Revolution • Earth revolves around the Sun • Voyage takes one year • Earth’s speed is 107,280 kmph (66,660 mph) • Rotation • Earth rotates on its axis once every 24 hours • Rotational velocity at equator is 1674 kmph (1041 mph)

  39. Revolution and Rotation Figure2.13

  40. Reasons for Seasons  • Tilt of Earth’s axis • Axis is tilted 23.5° from plane of ecliptic • Axial parallelism • Axis maintains alignment during orbit around the Sun • North pole points toward the North Star (Polaris) • Sphericity

  41. Axial Tilt and Parallelism Figure 2.14

  42. THE SEASONS 1)Parallel Rays 2) Diurnal ROTATION 3) Annual REVOLUTION (orbit) 4) Axial Tilt @ 66.50 to Plane of Ecliptic 5) Axial Parallelism

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