ET (Tundra Type)-here the average temperature of the warmest month is between 0°C and 10°C. It occupies hilly areas of Uttaranchal.
C.W. Thomthwaite
The eminent climatologistC.W.Thornthwaite while suggesting a suitable classification for world’s climate (1931, 1933 and 1948) on the basis of precipitation effectiveness (Precipitation-Evaporation or P.E. Ratio), thermal efficiency (Temperature Evaporation; TE Ratio), and seasonal concentration of rainfall divided India into 12 climatic regions. But he erred in putting major parts of the country under ‘mega thermal.’
AA’r-Tropical per Humid Climate with rainfall throughout the year. PE/TE more than 128, high temperature, heavy rainfall and tropical rain forest. It covers a narrow patch along the Western Ghats, Tripura and Mizoram.
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BA’w-Tropical wet with scarcity of moisture during winter, PE more than 128 but TE between 64 and 127. It includes remaining parts of Western Ghats and eastern parts of West Bengal.
BB’w-Warm wet climate with paucity of moisture during winter, PE/TE ratio between 64- 127. It spreads over Meghalaya, Assam, Nagaland and Manipur.
CA’w-Tropical sub-humid climate with winter dry, PE between 32-63, TE above 128. It stretches over major parts of the Peninsular India and southern parts of the Ganga Plain.
CA’w’-Tropical sub-humid climate with winter rainfall. It is spread over major parts of Tamil Nadu.
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CB’w-Sub-tropical and sub-humid climate with paucity of rains during winter, PE 32-63 and TE 64-127. This covers major parts of the Ganga- Brahmaputra plains.
DA’w-Tropical semi-arid climate with dry winter season, PE 16-31 and TE above 128. It lies over Kachchh, and south-eastern Rajasthan.
DB’w-Temperate sub-arid climate, PE 16- 31, TE 64-127 and winter dry. It includes northwestern Rajasthan, Punjab and south-western Haryana.
DB’d-Temperature semi-arid climate with paucity of moisture throughout the year, PE 16-31, TE 64-127. It occupies rain shadow area of the Sahyadris.
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D’-Taiga type climate with TE 16-31. It stretches over lower slopes of the Himalayas from Himachal Pradesh to Arunachal Pradesh.
EA’d-Tropical desert climate. TE above 128, PE less than 16, rain fall deficient in all seasons. This climatic type spreads over the western parts of Rajasthan (Thar Desert).
E’-Tundra type of climate where TE = 1-15. It includes northern parts of Kashmir.