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“I hear and I forget. I see and I remember. I do and I understand.”

“I hear and I forget. I see and I remember. I do and I understand.”. https://www.facebook.com/photo.php?fbid=474057782615238&set=a.456449604376056.98921.367116489976035&ty . THE ATMOSPHERE. Review, prevailing winds, fronts, pollutions, greenhouse effect & ozone layer September 27 2012.

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“I hear and I forget. I see and I remember. I do and I understand.”

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  1. “I hear and I forget. I see and I remember. I do and I understand.”

  2. https://www.facebook.com/photo.php?fbid=474057782615238&set=a.456449604376056.98921.367116489976035&ty THE ATMOSPHERE Review, prevailing winds, fronts, pollutions, greenhouse effect & ozone layer September 27 2012

  3. Review: The Atmosphere Concept map 1: Review

  4. Factors Affecting Air Pressure • Number of air molecules (e.g. N2, O2): the higher the number of molecules, the more frequent the collisions, therefore the higher the pressure.  Air pressure falls with increasing altitude. • Temperature of air: when temperature rises, air molecules move away from one another in order to restore a state of equilibrium, causing its density to drop, resulting in less collisions and thus, lower pressure.  Warm air is thus lighter than cold air and tends to rise. • Air particles will move away from high-pressure areas to low-pressure areas, resulting in winds.

  5. Anticyclones & Depressions Fig. 11: http://www.atmos.umd.edu/~meto200/3_13_03_lecture_files/slide0030_image276.jpg

  6. Prevailing Winds • Prevailing winds: major atmospheric currents that blow in a given direction according to global patterns of movement. • Polar easterlies: moving between the poles and the 60th parallel • * Westerlies: blow in the middle latitudes between the 30th parallel and the 60th parallel • Trade winds: easterlies moving between the 30th parallel and the equator

  7. Question 1 of the Day Why do you think easterlies are called easterlies? Why are westerlies called westerlies?

  8. Prevailing Winds Fig. 5: http://www.williamsclass.com/EighthScienceWork/Atmosphere/AtmosphereWind.htm

  9. Polar Cell • Between 60o and the poles in either hemisphere. • Air at 60o is warmer than air from polar regions, therefore it rises at 60o air from both sides then rushes in to fill the bottom space left behind by the risen air mass  warm air cools as it moves towards the poles and thus it sinks at the polar regions  it then turns and moves towards the empty space left behind by the rising air at 60o creation of Polar cell. (Pole) (60o) (30o) (0o)

  10. Ferrel Cell • Between 30o and 60o in either hemisphere. • Cooled air from equator sinks at 30o, pulling down adjacent air  space left behind by sunken air is replaced by air from both sides  the relatively warmer air collides with the cooler air from the polar regions at 60o, forcing it to rise in either direction  creation of Ferrel cell as well as a part of the polar cell. (Pole) (60o) (30o) (0o) Fig. 7: http://www.geol.umd.edu/~jmerck/geol100/lectures/33.html

  11. Hadley Cell • Between 0o and 30o in either hemisphere. • Warm moist air rises at (1)  • air cools, condenses and falls • as rain at (2)  cooled dry air • moves towards 30o, sinks and • warms up at (3)  cooled dry air starts to heat up at (4) over the hot dry deserts as it moves towards 0o again at (1). Fig. 6: http://andrewkfletchers.blogspot.ca/2012/03/operation-oasis-andrew-k-fletcher.html

  12. Cold Front • Cold front: Advancing cold air meets warm air  warm air rises rapidly  cools into thick cumulus clouds  wind and heavy rain Fig. 9: http://apollo.lsc.vsc.edu/classes/met130/notes/chapter11/cf_xsect.html

  13. Warm Front • Warm front: Advancing warm air meets cold air  warm air rises gently  thin, light nimbostratus clouds  long-lasting cloudy weather and showers. Fig. 10: http://earth.usc.edu/~stott/Catalina/WeatherPatterns.html

  14. Pollutions • Contaminants: • Sulphur dioxide (SO2), nitrous oxides (NOX), dust and other airborne particles from factories and car exhausts. • Mercury (Hg), arsenic (As) and lead (Pb) from combustion of fossil fuels, waste incineration and glass-making. • Chlorofluorocarbons (CFCs) from refrigeration systems and aerosol cans.  Due to winds, the formation of acid rain can occur near or far from the point of emission.

  15. Pollutions • Smog: a thick mixture of fog, smoke and atmospheric pollutants that hangs over urban areas when a high pressure system prevents it from rising into the atmosphere. • intensity and composition varies with weather and time Climate change: the abnormal modification of climatic conditions on Earth, caused by human activity.

  16. Question 2 of the Day Is the greenhouse effect good or bad for the Earth?

  17. Greenhouse Effect • Greenhouse effect: a natural process that allows the Earth to retain some of the heat it receives from the sun • Greenhouse gases (GHGs): mostly H2O, CO2, CH4and NOX

  18. Greenhouse Effect Fig. 1: http://www.nps.gov/goga/naturescience/images/Greenhouse-effect.jpg

  19. Ozone Layer • Ozone layer: the partofthe atmosphere, wherea high concentration of ozone molecules (O3)absorbs some of the ultraviolet (UV) rays from the sun; thus protecting us. • In 1987, 190 countries signed the Montreal Protocol to gradually phase out the use of CFCs until 2010.

  20. Question 3 of the Day Is the damage of the ozone layer reversible or irreversible?

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