Thornweight's World Climate Classification (THORNTHWAITE'S CLASSIFICATION OF WORLD CLIMATES) In English

Thornweight's World Climate Classification (THORNTHWAITE'S CLASSIFICATION OF WORLD CLIMATES)

 The famous American weatherman Thornwet has described climate classification by classifying it into two distinct parts. The first classification was presented in 1931 and 1933 and the second in 1948. Thornweight later revised its classification in 1955. The two classifications often look alike, but if we look closely, there is a difference between the two. In the classification made in 1933, only plants were considered as a special instrument of meteorology, with the help of which the elements of weather can be known. In the second classification in 1948, plants are considered as only natural means that keep the surface water from evaporating into the atmosphere.

 Thornweight has considered the effectiveness of precipitation, thermal efficiency and seasonal distribution of rainfall in the global climate classification. He recognized 23 classes by combining these three elements. If they are fully subdivided, 120 squares are created. Here only the basic facts of Thornavat's classification are explained.

 (1) Effectiveness of precipitation

 Thornwet considered the two big letters of English to be the basis for this element. Used (P) for rain and (E) for evaporation. To correctly determine the effect of rainfall by these two letters, a formula P / E is considered, by which the total rainfall received for 12 months is divided by the total evaporation of 12 months. To calculate evaporation, Thornwet used instruments to measure evaporation. Such instruments were not available in any country of the world except the United States. Precipitation effectiveness

 Ratio means

 Sahitya Bhavan Publications - The part of the whole precipitation that affects the origin and development of vegetation.

 This classification by evaporation formula (P / E) was related to the specific pattern of vegetation of each region, dividing it into 5 large parts according to the condition of humidity:

 

 3) The seasonal distribution of rainfall is so rarely found that the rainfall remains the same year after year. If it happens in some places

 Even then, there is a lot of difference in the climate there. There are many reasons for this difference, based on different elements. The seasonal distribution of rainfall is shown according to summer, winter and spring.

 Thornweight further divided the seasonal distribution of rainfall into further subdivisions, which were represented by lowercase letters of English (r, s, w, w 'and d).

 Thus, the climate of a place is determined based on the agglomeration of the above elements and indices. Accordingly, the climate of a region is represented by three varnas.

 The majority of India falls under the CA'w subdivision according to Thornweight's classification. Apart from this, BAw, AAT, CBw, DAW climate subdivisions are also found in India.

 Assessment of climate classification of Thonwet - Following are the salient features of Thornweight classification.

 (i) Two important indices (precipitation efficiency and thermal efficiency) have been used to differentiate into different climate types.

 (ii) Different classes have been used to indicate different climate types. (iii) Vegetation has been made the main basis in determining the climatic regions.

 (iv) Thornweight attempted to overcome the shortcomings in his plan by presenting the revised plan twice.

 Criticism

 Thornweight's classification of climate was also criticized:

 (1) Thornwet has described his second classification on the basis of climatic elements, in which the effect of physical elements (surface, vegetation, soil etc.) is not stated.

 (2) Due to this classification not being rational in principle, climatologist P.R. Crowe proved it wrong.

 (3) The formula used for vapor measurement does not fit for the vapor measurement of each place. Hence the classification is flawed.

 (4) Thornwet has made its classification very elaborate and complex.