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 18°C (64°F) - 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 18°C (64°F) and above -3°C (27°F)
  4. moist mid-latitude climates with severe winters: warm summers and cold winters. The average temperatue of the warmest month exceeds 10°C (50°F) and the coldest monthly average drops below -3°C (27°F)
  5. Polar climates: extremely cold winters and summers. The average temperature of the warmest month is below 10°C (50°F). 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.
  • so if P/E > 1 then Answer
  • if P/E < 1 then Answer

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