Koppen Climate Classification

I’m back from the TEK conference and it was amazing.  Still gathering my thoughts and processing everything I experienced.  Will post some key reflections and take-aways soon!

In the meantime, because I am a sucker for big-picture geographic classifications, I just saw this really cool simple climatic classification system from Koppen, a Russian-German climatologist and botanist.  (This is from Gordon et al.’s Stream Hydrology: An Introduction for Ecologists.)

The first letter is a broad, general category:

  • A – tropical rainy climate, no month’s average temperature cooler than 18 C (64 F).
  • C – humid warm climate, average temperature of the coldest month between 18 C and -3 C (64 F and 26 F)
  • D – humid cool climate, average temp of the coldest month below -3 C (26 F) and average temp of the warmest month above 10 C (50 F)
  • E – polar/alpine climate, average temp of warmest month below 10 C (50 F)
  • B – arid climate, evaporation exceeds rainfall.

The second letter classifies seasonal rainfall:

  • s – dry summer.
  • w – dry winter.
  • f – year-round rain.
  • m – monsoon-type rains.

The third letter “fine-tunes” the summer temperatures – a is warmest, b is middle, c is coolest – within the range of climates that have the first two classifications.

This last past seems the most squirrely to me – I would need to see a map to really understand what “a” “b” and “c” meant within a given climate type.  But the first two are really easy to assess.  Here in northern Vermont, we have a humid cool climate with year-round rainfall, so that’s “Df” (and probably Dfb given that Df would extend significantly north and south from here).  Coastal California would be “Bs.” (There’s an alternative classification for B climates that uses different letters to describe arid/semi-arid, but I’m using the standard one because I don’t think the alternative describes mediterranean climates very well.  I would probably modify the the system for my own purposes, as many other people have done, if I were to use it more extensively.)

The really interesting thing here, of course, would be to create some taxonomy for agriculture and built-environment design directions for each climate type, a la Bill Mollison’s Designer’s Manual.  Another “think-and-do tank” project waiting for someone to grab it!

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2 Responses to Koppen Climate Classification

  1. Neat idea, but why lump all arid climates together? Anyone who’s been to both the Wyoming high deserts and the Sonoran low deserts knows they aren’t all that similar. And, you’re right… Mediterranean climates are never really modeled well by anything.

  2. grousedrum says:

    yup, definitely needs refining for arid climates. do you know of a good, simple, anyone-can-do-it arid climate taxonomy that’s out there?

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