Köppen's classification of world climates was devised in 1918 by Dr Wladimir Köppen of the University of Graz (Austria). The classification is based on the idea that native vegetation is the best expression of climate, climate zone boundaries having been selected with vegetation limits in mind. Köppen's classification has undergone several changes and modifications since it was first devised.
The purpose of this paper is two-fold.
Firstly, a new extension to Köppen's classification of world climates is presented.
Secondly, the extension is illustrated with its application to Australia.
Köppen recognises five principal groups of world climates that are intended to correspond with five principal vegetation groups. These five climatic groups may be described as "tropical", "dry", "temperate", "cold" and "polar". Each of these climates are subdivided into types based upon temperature and precipitation differences. The present authors consider that, while retaining the essence of the Köppen classification, further division of the principal groups of world climates may better reflect human experience of those climates.
One may divide Köppen's "tropical" group into "equatorial" and "tropical", the first-mentioned corresponding to the Köppen "tropical" subdivision of "isothermal".
One may also divide Köppen's "dry" group into "desert" and "grassland", the aforementioned groups corresponding to the Köppen subdivisions of the "dry" group.
One may divide Köppen's "temperate" group into "temperate" and "subtropical". The latter group corresponds to that particularly warm component of the Köppen "temperate" group with a mean annual temperature of 18°C or above.
Köppen's "polar" group may have added to it the subdivision "polar maritime", this subdivision reflecting the climate of the sub-antarctic islands, which otherwise would have been classified (inappropriately) as "polar tundra". "Polar tundra" would be inappropriate for such climates (where the average temperature of the coldest month is -3°C or above). This is because, with the temperature not well below freezing, it is difficult for the ground to become frozen (a characteristic of "polar tundra").
Some minor subdivisions (for example, those dry climates on the west coast of continents with a high frequency of fog and those tropical climates with an autumn rainfall maximum) have been eliminated in order to focus upon the key climatic features.
The issues discussed above have been addressed in the climate classification presented. It now includes three additional major categories to that of Köppen. Specifically, the "tropical", "dry" and "temperate" categories have been divided as described above, and the "polar" category has been further subdivided, also as described above
The 8th Conference on Aviation, Range, and Aerospace Meteorology