Koppen used the temperature and precipitation statistics in his classification of the climate. These two weather elements are easy to measure. Because of this quality, these elements are most widely and most frequently used. Since Koppen’s classification is based on statistical parameters, each climatic region can be precisely defined.
Besides, the temperature and precipitation are the two most effective weather elements that exhibit the effects of climatic controls more clearly than any other weather elements.
These elements affect other aspects of our physical environment more directly than any other element. Obviously, the system of classification devised by Koppen is directly related to those aspects of environment which are clearly visible to us.
His climatic classification system is based on the relationship between the types of plants at a particular place and the climatic characteristics of the place. Thus, his scheme is not a mere abstraction.
Further, Koppen introduced the concept of effective precipitation which depends on the rate of potential evapotranspiration. Potential evapotranspiration is largely controlled by temperature.
Thus, in Koppen’s classification the relationship between heat and moisture factors gets due recognition. The moisture requirement of plants varies with the rate of evapotranspiration.
For example, the amount of precipitation sufficient to support coniferous forests in the cool temperate zone may support little plant life in a low-latitude desert.
Since climatic boundaries in Koppen’s system of classification were designed to delimit the vegetation regions, they may be taken to be ‘vegetation lines’.
The 10°C isotherm for the warmest month not only shows the southern boundary of the Tundra region, but it also represents the pole-ward limit of tree growth.
Because of a visible association of vegetation with climatic types, Koppen’s classification becomes all the more appealing to geographers.
Another advantage of this classification is that it is possible to assign a given place to a particular climatic sub-group only on the basis of certain easily acquired statistics about an area’s temperature and precipitation.
Besides, this system of climatic classification is descriptive and generalized and, therefore, it is more useful to geographers. However, this classification is not applied to any specific purpose.
Another unique feature of the koppen’s system is that it uses a shorthand code of letters for the climatic types, so that repetition of descriptive terms becomes unnecessary.
All the major climate groups, sub-groups, and further subdivisions are described by a combination of letters. Lastly, this classification is so simple and detailed that it can be easily used at different educational levels.