Many attempts have been made to classify the many disparate climates on Earth into a comprehensive and comprehensible system. One of the earliest began with Aristotle and his discussion of Temperate, Torrid, and Frigid Zones. The system that seems to be in almost universal use now is the Koppen system, developed by German climatologist and amateur botanist Wladimir Koppen in 1928.
Climate classification is useful as it groups locations based on commonalities within fundamental measurable characteristics. Climatic design strategies can then be carefully developed and tested for each of the classifications. This means that, once a designer knows the climate classification for a site, they have a head start as they can refer to a set of overarching design ideas from which to begin work.
The Koppen System
Koppen spent time updating and modifying his system of climate classification right up until his until his death at 94 in 1940. Since then it has been modified by a number of geographers, most notably the late Glen Trewartha of University of Wisconsin, whose version is probably in the widest use today.
(Image from http://koeppen-geiger.vu-wien.ac.at/ .)
The modified Koppen system uses letters to denote the six major climate regions and their 24 sub-classifications. These regions are based on average monthly temperature and precipitation values. Whilst it does not take full account of factors such as cloudiness, solar radiation, wind or even extremes in temperature, it still remains a useful system.
Whilst the individual zones are shown in the map above with clearly delineated boundaries, it is important to note that the system is just a guide to average climate trends and that the areas between zones represent a gradual transition between climates.
Major Climate Regions
The following links are to pages that contain a description of each climate type as well as a series of design strategies for buildings within it:
- A for Tropical Humid Climates.
- B for Hot Dry Climates.
- C for Mild Mid-Latitude Climates.
- D for Cold Mid-latitude Climates.
- E for Polar Climates.
- H for Highland Climates.
Note: The H classification was added after Koppen created his system.
Subtypes for Temperature
Based on monthly temperature variations, each major classification can have the following sub-types:
- a - warmest month above or equal to 22 C (for C or D climates)
- b - warmest month below 22 C (for C or D climates)
- c - less than four months over 10 C (for C or D climates)
- d - same as 'c' but coldest month below -37 C (for D climates)
- h - hot and dry: all months above 0 C (for B climates)
- k - cool and dry: at least one month below 0 C (for B climates)
Subtypes for Precipitation
Based on monthly rainfall values, each major classification can have the following sub-types:
- s - dry season in summer: when 70% or more of annual precipitation falls in winter (for C climates)
- w - dry season in winter: when 70% or more of annual precipitation falls in summer (for A, C, or D climates)
- f - constantly moist: rainfall consistent throughout the year (for A, C, or D climates)
- m - monsoon rain: short dry season, use when precipitation in driest month is less than 6 cm and total annual precipitation exceeds 125 cm, when both 'w' and 'm' subtypes are met, 'm' subtype takes precedence, don't use both subtypes (for A climates)
Useful References
- World Map of the Koppen-Geiger Climate Classification
- http://koeppen-geiger.vu-wien.ac.at/
- Koppen Climate Classification System - Wikipedia
- http://en.wikipedia.org/wiki/K%C3%B6ppen_climate_classification
- Climate Effects on Human Health
- http://www.ciesin.org/docs/001-338/001-338.html