Climate Classification - The Koppen System

  • widely used system that classifies climatic regimes according to:
    • annual and monthly averages of temperature
    • annual and monthly averages of precipitation
  • devised by Waldimir Koppen (1846-1940)
  • identified five primary climate types:
    1. Tropical moist climates: all months have an average temperatue above 18C (64F) - no real winter season
    2. dry climates: deficient precipitation most of the year. Potential evaporation and transpiration exceed precipitation.
    3. moist mid-latitude climates with mild winters: warm-to-hot summers with mild winters. The average temperature of the coldest month is below 18C (64F) and above -3C (27F)
    4. moist mid-latitude climates with severe winters: warm summers and cold winters. The average temperatue of the warmest month exceeds 10C (50F) and the coldest monthly average drops below -3C (27F)
    5. Polar climates: extremely cold winters and summers. The average temperature of the warmest month is below 10C (50F). There is no real summer season...., bummer!!
  • each climate group contains subgroups - we will talk about these shortly...
  • The Koppen system has been modified, most notably by C. Warren Thornthwaite (1899-1963)
  • Thornthwaite emphasized the importance of precipitation (P) and evaporation (E) by devising the P/E ratio.....
  • The P/E ratio is monthly average precipitation divided by monthly average evaporation.

Now, let's look at the global distribution of climate based largely on the work of Koppen and the Koppen scheme....