Trewartha Climate classification of Indian Climate:NCERT//WBSLST//NTA NET//KVS/NVS/DSSSB

• The Trewartha climate classification is a climate classification system first published by American geographer Glenn Thomas Trewartha in 1966
• The Trewartha climate classification system is a modified version of the Köppen climate classification, which categorizes climates based on temperature and precipitation patterns.
• Besides these, the effects of land and water surfaces on the climate of an area have also been taken into consideration.
• T. Trewartha simplified Koppen's classification and presented his own classification of climate regions

As per Trewartha, there are six major climatic regions of the world.

A: Tropical  Climate

B: Dry climate

C: Humid Subtropical climate

D: Humid temperate climate

E: Polar climates

H: highlands

They are as follows:

A: Tropical Rainy Climatic Group

Am—Tropical Monsoon

Aw—Tropical Savannah

B: Dry Climatic Group

BS—Tropical Steppe (semi-arid)

Bsh—Sub-Tropical Steppe

Bwh—Sub-Tropical Desert

C: Humid Mesothermal Climatic Group

Caw—Sub-Tropical Humid (Dry Winters)

H: Mountain Climate

1. a – indicates hot summers with the warmest month having over 22° C temperature.
2. h – is used when the mean annual temperature is 18° C.
3. m – stands for heavy but seasonal monsoon rainfall; the dry period is very short.
4. s – means steppe or semi-arid climate.
5. w – stands for a desert.

4 out of six climatic regions found in India are A, B, C, and H. These four climatic regions are further divided into seven climatic regions.

A: Tropical Climate

The tropical climate is found in those regions where annual average temperatures do not fall below 18 degrees centigrade.

In India, " A: Tropical Climate" is categorized into two types:

Tropical Wet Monsoon ( Am)

Tropical Savanna ( Aw)

Tropical Wet monsoon type( Am):

Tropical monsoon ( Am)'s climatic zone average annual temperature is about 27 degrees C and annual rainfall is over 250 cm.

The western Coastal plains and the Southern northeastern states ( Tripura, Mizoram, and Meghalaya) come to Tropical Monsoon. It features distinct wet and dry seasons. The monsoon brings heavy rainfall during the summer months, while the rest of the year is relatively dry.

Tropical wet and dry Savanna(Aw ):

The majority of India, including areas like the Peninsular Plateau, Mumbai, Delhi, and Kolkata, falls under this category. It features distinct wet and dry seasons. The monsoon brings heavy rainfall during the summer months, while the rest of the year is relatively dry.

The region receives about 100 cm of annual rainfall and the majority of rainfall is received in the summer season.

B: Dry climate:

It is divided into three types:

BS

BSh

BWh

BS: Semi-arid or steppe climate

BS or Semi-arid or Steppe climatic regions are found in the Rainshadow zone of the Western Ghats.

Bsh:

"Bsh" climate is a region where the tropical and subtropical desert climates. In this climatic zone, temperate is less than 23 degrees C.

 The area of this climatic zone includes parts of Gujarat, Rajasthan, and Haryana.

BWh: hot desert climate:

"BWh" or hot desert climate is primarily found in West Rajasthan and Kutchcch regions of Gujarat. This climate is characterized by Thorn bushes and vegetation like cactus.

C:  subtropical climate with dry and cold.

A subtropical climate with a dry and cold climate (Caw) is mainly found in the northern plain of India, where there is mild winter ( average winter temperature is less than 18 degrees centigrade) and the region receives rainfall in mainly summer.

H: highlands

"H: Highland" climatic zones are mainly found in the Himalayan region from Jammu Kashmir to Arunachal Pradesh. It is characterized by low temperatures due to the highlands. This climatic zone also receives snowfall in winter.