Which climatologist used 'Precipitation effectiveness ratio' in worlds climatic classification?

Question

Accepted Answer

Thornthwaite is the correct answer because his climatic classification system, developed in 1931 and later revised in 1948, heavily relies on the concept of "potential evapotranspiration" and the "Precipitation Effectiveness (P-E) ratio." This ratio, calculated as precipitation divided by potential evapotranspiration, is a key component in determining the moisture index and classifying climates based on their water balance. Thornthwaite's system emphasizes the importance of water availability for plant growth and uses the P-E ratio to define different climate types, such as humid, subhumid, semi-arid, and arid.

Here's why the other options are incorrect:

*   **Koeppen:** Koeppen's climate classification system is primarily based on temperature and precipitation, using specific temperature thresholds for different vegetation zones. While precipitation is a factor, he did not use the "Precipitation effectiveness ratio" as the primary determinant in his classification. His system relies more on absolute values of temperature and precipitation rather than a ratio of precipitation to potential evapotranspiration.

*   **Trewartha:** Trewartha's climate classification is a modified version of the Koeppen system. While he made adjustments to better reflect mid-latitude climates, he still fundamentally used temperature and precipitation data as the basis for his classification, not the Precipitation Effectiveness ratio.

*   **Kendrew:** Kendrew's climate classification is also a modification of the Koeppen system, primarily focused on regional variations and refinements. Like Trewartha, he did not employ the Precipitation Effectiveness ratio as a central component of his classification scheme. His work built upon Koeppen's framework rather than introducing a fundamentally different approach based on water balance and the P-E ratio.