Climatic regions of India

Climate: The average of weather conditions over a longer period of time is called climate.

The climate of India is Monsoonal in rhythm and character. India with the rest of southeast Asia has the Tropical Monsoon Climate as a large area of it lies in the tropical zone and is largely affected by the monsoon winds which emphasizes the unity of the region.

Factors affecting the climate of India
  1. Factors related to location and relief latitude
  2. Factors related to air pressure and wind

Factors related to location and relief latitude

The angular distance of a location from the equator in the North-South direction is called latitude. The tropic of Cancer passes through the central part of India in the East-West direction. Thus, the Northern part of India lies in the sub-tropical and temperate zone and the part lying in the South of the Tropic of Cancer falls in the tropical zone.

  • The Himalayan Mountains
  • Distribution of land and water
  • Distance from Sea
  • Altitude
  • Relief

Factors related to air pressure and wind

  • Distribution of air pressure and winds on the surface of the earth
  • Upper air circulation is caused by factors controlling global weather and the inflow of different air masses and jet streams.
  • The inflow of Western cyclones known as Western disturbance during the winter season and tropical cyclones/depressions during the South-West monsoon period into India, creating weather conditions favorable to rainfall.
Climatic regions of India

The climate of whole India is Monsoon type but there are many regional variations. These variations are sub-type of monsoon climate and form the basis of the identification of climatic regions.

A climatic region has a homogenous climatic condition which is the result of a combination of two factors i.e. temperature and rainfall.

India has five major types of climate:

  1. Tropical Climate: In this type of climate, the mean monthly temperature is above 18° C throughout the Year.
  2. Dry Climate: The temperature is high and rainfall is low. If the dryness is less, it is semi-arid (S), if it is more, the climate is arid (W).
  3. Warm Temperature Climate: The mean temperature of the winter months varies between 18° C to minus 3 ° C.
  4. Cool Temperature Climate: The temperature of the warmest month is over 10 degrees C and of the coldest month is under minus 3°C.
  5. Ice Climate: The mean temperature of the warmest month is under 10 ° C.
Classification of Climatic regions of India:

Koeppen’s scheme

Koeppen used capital and small letters to denote climate types and subtypes. According to Koeppen India can be divided into eight climatic regions:

  1. Amw-Monsoon with the short dry season- west coast of India, South of Goa
  2. As- Monsoon with dry summer – Coromandal coast of Tamil Nadu
  3. Aw- Tropical Savannah – Most of Penisular Plateau, South of Tropic Cancer
  4. BShw – Semi-arid Steppe climate- North-Western Gujarat, Some parts of Western Rajasthan and Punjab.
  5. BWhw- Hot desert – Extreme Western Rajasthan
  6. Cwg- Monsoon with dry winter- Ganga Plain, Eastern Rajasthan, Northern Madhya Pradesh, most of North – East India.
  7. Dfc- Cold humid winter with short summer – Arunachal Pradesh
  8. E- Polar type – Jammu and Kashmir, Himachal Pradesh, and Uttarakhand.
Koeppen's scheme - Climate

Koeppen’s scheme – Climatic regions of India

Koeppen's scheme - division of climate

Classification of Indian climate on the basis of Koeppen’s scheme

Thornthwaite’s scheme

Thornthwaite’s scheme is classified on the basis of the concept of water balance. As the rainfall of a place is less than water that is lost by evaporation and transpiration, then the place has a water deficit. If the rainfall is more than the need, then it is surplus.

According to Thornthwaite’s method, the climatic region of India can be identified as:

  1. Perhumid (A)
  2. Humid(B)
  3. Moist sub-humid (C2)
  4. Dry sub-humid (Cj)
  5. Semi-arid (D)
  6. Arid (E)
Thornthwaite’s Scheme- Climatic regions of India

Climatic regions of India on the basis of Thornthwaite’s Scheme

Trewartha’s Scheme

Trewartha’s classification of climate is a modified form of Koeppen’s scheme. It is based on the vegetative, agricultural, and geographical regions of India. On the basis of Trewartha’s classification there are four major climatic groups A, B, C, and H, that are further subdivided into seven climatic types:

  • A – Tropical rainy climate Group
    1. Am – Tropical Monsoon- This type of Climate cover the Indian region of Western Ghat, Western Nagaland, and Tripura.
    2. Aw- Tropical savannah – The region covers the whole of the Deccan Plateau except a narrow strip of rain – shadow area in the East of Western Ghats, northeastern Gujarat, Southern Madhya Pradesh, Southern Bihar, Orissa, Andhra Pradesh, and Tamil Nadu.
  • B – Dry climatic group
    1. BS – Tropical Steppe (semi-arid)- The region covers interior Karnataka, Central Maharastra, Western Andhra Pradesh, and interior Tamil Nadu.
    2. Bsh- Subtropical Steppe – It covers an area from Punjab to Kachchh
    3. Bwh – Subtropical Desert – Western Rajasthan and Kachchh
  • C – Humid Mesothermal climatic group
    1. Caw – Subtropical Humid (Dry winters)- Punjab foothills, Uttar Pradesh, Bihar, West Bengal, Assam, and Arunachala Pradesh
  • H – Mountain Climate – Mountain area of Kashmir and Arunachal Pradesh
Trewartha’s Scheme

Trewartha’s Scheme- Classification of the Indian climate

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