Introduction: A climatic region is an area which has uniformity in the various elements of climate. Among the elements of climate, temperature and rainfall are the two most important elements that play a vital part in the classification of climatic regions in India. Thus a climatic is an area which generally shows uniformity in temperature and nature of rainfall.
Different parts of India show a variety of temperature and rainfall. Thus classifying India into different climatic regions in rather difficult. So climatologists do not agree on any one climatic classification of India.
Following Koppen, Trewartha classified India into Eight Climatic Regions. This classification is based on variations in temperature, rainfall and natural vegetation. The reason for taking natural vegetation as an indicator of climate is that different natural vegetations are found in areas having different climates.
The Climatic Regions of India are:
1. Tropical, Very Humid Monsoon Region: This climatic region is found in the west coastal plain of India. It is characterized by average annual rainfall above 300 cm and annual temperature varying between 18° to 27°C. The very heavy rainfall causes the presence of mainly tropical evergreen trees.
2. Tropical Savana: This climate is found in Gujarat, Maharashtra, southern West Bengal, Orissa, etc. The climatic characteristics are very hot summers and dry winters. These climatic characteristics cause trees to shed their leaves in the dry months. So deciduous trees and savanna grass grow in this region.
3. Tropical with Dry Summer and Humid Winter Region: This region is found in the southern part of the east coast where rainfall occurs mainly in winter and summers are often dry.
4. Tropical, Semi-arid and Sub-tropical Steppe Region: This climate is found in the rain-shadow region of the Western Ghats, eastern Rajasthan, and south-eastern Punjab. It is characterized by low rainfall and extremes of climate. As a result stunted trees, grass, bushes, thorny trees etc are seen.
5. Hot Desert Region: It is found in the desert region of western Rajasthan. Rainfall is very low with summer temperatures rising to 48°. Vegetation is scare except for thorny plants.
6. Temperature with Short Summer and Cold Humid Regional: This climate is found in Arunachal Pradesh and eastern Assam. The annual rainfall is over 300 cm. summer is of short duration and temperatures do not rise because of altitude.
7. Humid Sub-tropical Monsoon Region with Dry Winters: This climate is found in most of the plain of North India. Rainfall occurs mainly in summer with the amount decreasing from the east to the west. Most of the trees are of deciduous type with some evergreen trees.
8. Cold Mountain Climate Region: This climate is found in the higher parts of western Himalaya. Throughout the year it is very cold and snowfall occurs in winter. Pastures are found in the higher slopes in summer and coniferous trees grow on the lower slopes.