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classification of climatic regions

  • by latitude:
    • equatorial
    • tropical
    • sub-tropical
    • temperate
    • sub-polar
    • polar
  • by temperature-rainfall:
    • a region can be graphed on a kind of climograph called a thermohyet which has mean monthly temperature on Y-axis and mean monthly rainfall on X-axis
  • Koeppen-Geiger system:
    • a climate can be classed using 3 letters:
      • 1st letter: relates to temperature
      • 2nd letter: relates to rainfall
      • 3rd letter: relates to temperature
  • by frequency of different types of air masses:
    • parallels the Koeppen-Geiger system
    • is relevant to shape of thermohyet loop
  • by statistics:
    • usually by factorial analysis

climatic change:

  • factors that may effect climate:
    • random element inherent in the atmosphere
      • including volcanic eruptions
    • regular rhythms due to Earth's spin & orbit:
      • those which account for daily & seasonal changes, modified by persistence
      • Milankovitch variations due to long term oscillation of earth's axis every 40,000yrs & variation in its orbital eccentricity every 92,000 yrs
    • not so regular rhythms such as:
      • sunspot activity
      • rotation of the oceanic gyres
      • the Southern Oscillation
      • the quasi-biennial oscillation
      • continuous processes such as mountain building & erosion
      • polar icebergs floating away from the polesmay cause sudden hemispheric cooling by as much as 5degC within a century
    • there may be threshold states which once passed create an alternative oceanic or atmospheric current and thus climatic conditions
      • eg. Ice Age perhaps
      • eg. reversal of currents during an El Nino year
    • influence of human activities:
      • carbon dioxide & other greenhouse gas levels:
        • increased production by industry, etc
        • decreased removal by decreased vegetation & forests
      • stratospheric dust via pollution, nuclear explosions
      • altered ocean currents & water flows by damming & the creation of artificial lakes
      • altered surface albedo by replacing vegetation with bitumen, etc
      • destruction of stratospheric ozone levels
climate/climate4.txt · Last modified: 2020/01/06 19:57 by gary1

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