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HPU NCS2200 Chapter17& 18 primary atmosphere structure and function
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HPU NCS2200 Chapter17& 18 primary atmosphere structure and function

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HPU NCS2200 earth science for elementary education majors summer 2014 online class atmosphere structure and function lecture 1

HPU NCS2200 earth science for elementary education majors summer 2014 online class atmosphere structure and function lecture 1

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  • 1. 17.5 Atmospheric Structure ►Troposphere – the layer we live in  Most weather  All clouds & water vapor  Cools as you go up ►Tropopause – ~17km high, the cooling ends abruptly, little mixing with troposphere
  • 2. 17.5 Atmospheric Structure ►Stratosphere – temp constant to 35km  Increases up to 50km  Ozone forms here  Above 55km (stratopause) temps fall again ►Mesosphere – thin air, very cold up to 80km ►Thermosphere – above 80km, temps rise rapidly (to just below freezing!)  Hi-energy environment
  • 3. Fig. 17.10, p.440
  • 4. 18.1 Incoming solar radiation ►Light – behaves like a wave and a particle  Photons – elementary particles of light  Electromagnetic radiation – light also behave as energy waves, perpendicular electrical and magnetic waves ►Wavelength – distance between wave crests ►Frequency – number of waves passing a point/sec. ►Electromagnetic spectrum – continuum of electromagnetic wavelengths
  • 5. 18.1 Incoming solar radiation ►Absorption – when something absorbs radiation, the photon’s energy can initiate chemical and/or physical reactions  Excited state – absorbed photons makes electrons get “excited”  Emission of radiation – when the exited electrons “settle down” they emit light ►All objects emit some radiation ►Emission color (wavelength) relates to temperature
  • 6. 18.1 Incoming solar radiation ►Reflection –electromagnetic radiation bouncing from a surface  Albedo – proportional reflectance of a surface ►(e.g.: a perfect mirror would have an albedo of 100%) ►Glaciers & snowfields approach 80-90% ►Clouds – 50-55% ►Pavement and some buildings – only 10-15%
  • 7. Fig. 18.4, p.454
  • 8. Fig. 18.5, p.455 ► Scattering – gases and water droplets scatter light in all directions  short “blue” wavelengths scatter more, so skies are blue
  • 9. 18.2 the radiation balance ►Earth’s surface absorbs light energy  Most is re-emitted, mainly as heat  Greenhouse effect – some gases and water vapor absorb some of this heat ►Dust, clouds, aerosols, particulates all affect atmospheric temperature  Hi-altitude dust can reflect light  Lo altitude particles can absorb heat
  • 10. Fig. 18.6, p.455
  • 11. 18.3 Energy storage & transfer – climate’s driving mechanism ►Temperature – is proportional to the average speed of atoms or molecules in a sample.  E.g.: hot water molecules move faster than cold water molecules ►Heat – is a measure of the total energy in a sample  average energy X number of molecules  E.g.: bathtub of ice has more heat than a cup of tea
  • 12. 18.3 Energy storage & transfer – climate’s driving mechanism ►Conduction – transfer of heat by direct collisions of molecules  Heat, good conductor; air, poor conductor ►Convection – transfer of heat by the motion of a fluid medium ►Advection - horizontal air flow (meteorological term)
  • 13. Fig. 18.8a, p.457 Convection example: heat from a stove heating a room
  • 14. Fig. 18.8b, p.457 Convection within the atmosphere
  • 15. p.459 Recall that the Earth is curved And lines of Latitude Are horizontal to the Equator and increase in Degrees from 0 to 90
  • 16. 18.4 temperature changes with latitude & season ►Temperature decreases as latitude increases  Light strikes more directly at low latitudes ►more energy per unit area, heats more effectively  At high latitudes, the sun strikes quite obliquely ►At some point during the year at poles, it doesn’t strike at all
  • 17. Fig. 18.11, p.460
  • 18. Fig. 18.10, p.460
  • 19. 18.4 temperature changes with latitude & season ►The seasons – related to orbital parameters  Earth’s axis is tilted. During northern summer, the light hits more directly and in winter less so  Tropics – the latitudes of 23.5o N/S are where light his directly on summer and winter solstice  Equinox, when an area gets 12 hours each of light and dark ►On average, all areas of the globe receive the same sunlight time annually
  • 20. Fig. 18.12, p.461
  • 21. 18.5 Temperature changes with geography ►Altitude – temperature decreases with altitude ►Ocean effects – land heats more quickly than water, so inlands see greater temperature extremes  Currents often transfer heat to moderate temperatures (e.g.: the Gulf Stream)
  • 22. 18.5 Temperature changes with geography ►Cloud cover and albedo  Clouds intercept light energy ►They cool during day by blocking the sun  Clouds have high albedo, turning incoming energy back towards space ►Then warm at night by trapping ground-emitted heat  Clouds have high albedo, turning outgoing energy back to ground ►Snow effects solar input in similar fashion, it is reflective while soil/rock is not
  • 23. Fig. 18.18, p.466