Climate of India

The factors affecting the climate of a place are:

1. Location — Climate of a place depends on its location. Places located in tropical region are hotter than the places located in temperate region.
2. Altitude — The temperature decreases with increase in the height at the rate 1°C for every 166 m. Therefore, places situated on height have temperate climate.
3. Distance from sea — Places situated near sea have moderate climate while places situated away from sea have extreme type of climate.
4. Physical features — Presence of mountain ranges often decide the climate of a place. For example, the Himalayas act as a barrier to the incoming cold Siberian winds. They also intercept the monsoon winds resulting in heavy rainfall in Indo-Gangetic plain.

The climate of India is Tropical Monsoon Type.

The chief characteristic feature of the tropical monsoon type of climate is alteration of seasons.

Onshore winds — Wind that blows from the sea towards the land is called onshore winds.

Offshore winds — Winds that blows from the land towards the Sea is called offshore winds.

The monsoon season is important for a number of reasons in India:

1. Agriculture — The monsoon season is crucial for agriculture in India, as it provides the necessary moisture for crops to grow. Many of the crops in India, such as rice, wheat, and sugarcane, rely on the monsoon rains to provide the necessary water for their growth.
2. Water resources — The monsoon season replenishes the water resources in India, including rivers, lakes, and reservoirs. This is especially important in regions that rely on these sources of water for irrigation, drinking, and other purposes.
3. Economy — The monsoon season is also important for the economy of India, as it supports many sectors of the economy, including agriculture, forestry, and tourism.

Local winds that pass through India are:

1. Kali Baisakhi
2. Loo
3. Mango Showers

The Arabian Sea Branch is more important branch because of the following reasons:

1. Arabian Sea Branch is almost thrice the volume of the Bay of Bengal Branch.
2. Arabian Sea Branch provides rain in the entire country while the Bay of Bengal branch provides rain in north-eastern part only.

Kerala is the first state to receive the monsoon winds and the last to see its retreat in India.

Two important characteristic features of the Indian monsoons are:

1. Indian monsoons are erratic, unpredictable, irregular and unevenly distributed.
2. Indian monsoons are orographic in nature. The effects caused due to the Himalayas and the Western Ghats bring most of the monsoon rainfall.

The different seasons of India are:

1. The Hot Dry Season — March to May
2. The Rainy Season or the season of South-West Monsoon — June to September.
3. The season of retreating South-West Monsoon — October to November
4. The Cold season or the season of North-East Monsoon — December to February

The word Monsoon has been derived from the Arabic word 'Mausim' which means season.

Monsoon winds are different from the land and sea breezes in the following ways:

There are great variations in India's climate because of presence of different physical features and the large extent of the country. Following are the factors that cause variations in India's climate:

1. The places lying to the north of Tropic of Cancer experience continental type of climate while places lying to the south of Tropic of Cancer experience hot climate with average temperature of 25°C to 27°C throughout the year.
2. The places situated on the vast east-west coastline of India experience equable or maritime type of climate with annual temperature range of about 3°C to 5°C whereas the places in the interior north have the annual temperature range upto 20°C.
3. The Monsoon are erratic, unpredictable, irregular and unevenly distributed. Due to this the annual rainfall varies from about 1187 cm at Mawsynram in Cherrapunji, the highest in the world to less than 25 cm in Thar desert in Rajasthan.
4. Places situated at higher altitudes are cooler as compared to places in the plains.
5. Presence of the Himalayan range also influences the climate of India by obstructing Siberian winds and intercepting Monsoon winds.

The Himalayas act as a perfect climatic divide because:

1. The great Himalayan range obstructs the bitter cold winds from Siberia from entering the Indian Subcontinent.
2. The Himalayan range intercepts the rain-bearing south-west monsoon winds, forcing them to shed their moisture, resulting in heavy rainfall in the North-East and Indo-Gangetic Plain.

The South-West Monsoon winds are responsible for the rain experienced over the greater part of India.

India experiences rain in the months from June to September which is the season of the South-West Monsoon.

The winter rainfall in the north-west part of India occurs due to westerly depressions or temperate cyclones originating in the Mediterranean sea. On the contrary the rainfall experienced on the eastern coastal areas in winter is due to North-East monsoon winds.

Kanyakumari experience an equable climate because of land breeze and sea breeze as it is situated on sea coast.

Maharashtra receives scanty rainfall because it lies in the rain shadow of Western Ghats.

The western part of India gets very less rainfall due to following reasons:

1. The Aravali's alignment is parallel to rain-bearing South-West Monsoon winds and as such they do not offer any obstruction. Furthermore, these hills are very low.
2. The moisture-laden winds passing over Rajasthan do not saturate as the heat in the desert region increases their capacity to hold moisture. Thus they reach Shivaliks without shedding their moisture.

Western disturbances are Westerly depressions or Temperate cyclones originating in the Mediterranean sea. They cause winter rain in Punjab, Haryana and Western Uttar Pradesh and snowfall in Himalayan belts.

Northern India (Punjab, Haryana and Uttar Pradesh) receives rainfall in winter and summer as well.

Mawsynram receives the heaviest rainfall in the world. This place belongs to Meghalaya State of India.

The Bay of Bengal branch of South-West monsoon winds is responsible for causing heaviest rainfall in the region.

The leeward side of the mountain that do not receive or receive very less rainfall is called rain shadow area. For example, Maharashtra gets very less rainfall as it is the rain shadow area of the Western Ghats.

North-East Monsoon winds bring rains to the Tamil Nadu coast.

1. In spite of the Aravalis many parts of Rajasthen do not receive much rain because the Aravalis do not obstruct the Monsoon winds due to their parallel alignment to the winds and low heights of Aravalis.
2. The Malabar coast receive more rainfall because of the strong Arabian sea branch of the South-west monsoon while Coromandal Coast gets its share of rainfall from North-East Monsoon which is weaker and has less capacity.
3. Punjab has three sources of rain as it gets its share from the Arabian sea branch, the Bay of Bengal branch (deflected from the eastern parts) and the western disturbances.
4. Mawsynram lies in the windward side while Shillong lies in the leeward side of Khasi hills. Therefore, Mawsynram receives more rain than Shillong.

The winter rain is caused by Western Disturbances in North and North-East Monsoon winds in Tamil Nadu. In northern India, rain is caused by Westerly depressions or Temperate cyclones originating in Mediterranean Sea. These rains are beneficial for rabi crops like wheat and Barley. The winter rains caused by North-East Monsoon winds brings rainfall to Tamil Nadu and parts of Andhra Pradesh. This rainfall is heavy, stormy and destructive for crops.

Chennai

(a) Annual Range of temperature = 32.5 - 24.5 = 8

(b) Total rainfall = 2.8 + 0.7 + 0.7 + 1.5 + 4.5 + 5.1 + 9.5 + 11.3 + 12.4 + 28.1 + 34.5 + 13.6 = 124.7

(c) Chennai received maximum rainfall in the month of November. The North-East Monsoon winds after crossing the Bay of Bengal gather enough moisture. As they, strike the Coromandal coast, they bring heavy rainfall to Chennai and Tamil Nadu in the month of November.

Pune

(a) Annual range of temperature = 29.7 - 20.5 = 9.2

(b) Total rainfall = 0.15 + 0.15 + 0.15 + 1.5 + 2.7 + 11.4 + 16.7 + 9.0 + 13.4 + 9.0 + 2.7 + 0.3 = 67.15

(c) Pune receives maximum rainfall in the month of July because it gets its rainfall from south-west monsoon which strikes the western coast in June but the total rainfall is less because Pune lies in the rain shadow of western ghats.

New Delhi

(a) Annual range of temperature = 33.6 - 13.8 = 19.8

(b) Total rainfall = 2.5 + 2.1 + 1.3 + 0.8 + 1.3 + 7.7 + 17.9 + 18.4 + 12.3 + 1.0 + 0.2 + 1.0 = 66.5

(c) Delhi receives maximum rainfall in August as it gets its rainfall from south-west monsoons which reaches Delhi by that time.

Kolkata

(a) Annual range of temperature = 30.6 - 19.4 = 11.2

(b) Total rainfall = 0.7 + 2.8 + 3.6 + 4.8 + 14.5 + 30.2 + 31.8 + 32.3 + 25.1 + 10.6 + 1.8 + 0.4 = 158.6

(c) Kolkata receives maximum rainfall in August as it gets rainfall from the Bay of Bengal Branch of the monsoon which reaches the eastern coast (Calcutta) by then.

1. Mumbai is located on the western coast of India, while Pune is located further inland. The Western Ghats obstruct the South West Monsoon winds. Mumbai lies on the windward side of Western Ghats and receives heavy rainfall from South West Monsoon. Pune lies on the leeward side of Western Ghats and hence, receives very less rainfall.
2. The moisture laden winds passing over Rajasthan do not saturate because the heat in the desert region increases their capacity to hold moisture.
3. By 1st September, with the apparent movement of the sun towards south, the low pressure in central India starts weakening, and is no longer able to attract the monsoon winds towards land. During Autumn equinox when the sun shines directly over Equator, the high pressure begins to build over mainland and subsequently with low pressure over the sea, S.W. monsoon withdraws from India in October/November.

1. Retreating Monsoon
2. Western disturbance
3. Monsoon Winds

1° C for every 166m

SW to NE

Periodic winds

tea crop

Arabian sea

Tamil Nadu

December to February

May

Northeast to Southwest

Mediterranean Sea