• Climate is one of the basic elements in the natural Environment. It determines the landforms, soil, vegetation and agriculture of a place. Climate of a place is determined by the following factors such as

1. Latitude
2. Altitude
3. Distance from the sea
4. Wind
5. Position of Mountains
6. Latitude

• India lies between 8⁰4’ N to 37⁰6’ N Latitudes. 23⁰30’ N latitude tropic of cancer passes across the country. The parts of the country to the south of tropic of cancer being closer to the Equator, experience high temperature throughout the year.

2. Altitude

• Temperature decreases with increasing altitude from the earth surface at the rate of 1⁰C for every 165 meters.

3. Distance from the sea

• The places to the north of Tropic of cancer experience “continental climate”, where the summer is extremely hot and the winter is extremely cold. The Tropical South, which is enclosed on three sides by Arabian Sea, Indian Ocean and Bay of Bengal, experiences ‘Equable climate’.

4. Wind

• The wind that blows from the sea to the land is called sea breeze and that which blows from the land to the sea is called land breeze.

Jet Stream

• Air currents in the upper layers of the atmosphere is known as Jet streams. It could determine the arrival and departure of monsoon winds in India.

5. Position of Mountains
6. a) The great Himalayan range in the North India obstructs the bitter cold winds from central Asia to India.
7. b) The Himalayan range intercepts the rain-bearing southwest monsoon winds, forcing them to shed their moisture, resulting in heavy rainfall in the northeast and Indo – Gangetic Plain.
8. c) The Aravalli range intercepts south west monsoon winds and so western side of this range is a desert and receives very less rainfall.

• EL – Nino is a complex weather phenomena that appears once in every five to ten years, bringing drought, floods and other weather extremes to different parts of the world. It is also a cause for the delay of south west monsoon onset in India.

Climate of India

• The word ‘monsoon’ owes its origin to an Arabic word ‘Mausim’ meaning ‘season’. The winds which reverse their directions completely between the summer and the winter is known as Monsoon Winds. Due to these monsoon winds, India experiences Tropical monsoon climate.

The salient features of Tropical monsoon climate

1) The Monsoon winds are classified into Southwest Monsoon and Northeast Monsoon on the basis of the direction from where they blow.

2) They are caused due to the differential heating of land and sea.

3) The main feature of monsoon winds is alternation of seasons which determines the climate of the India.

Season

1) Summer (March to May)

2) South west Monsoon. (June to September)

3) North East Monsoon (October to November)

4) Winter (December to February)

1. Summer (March-May)

• During this season the sun’s rays are vertical over the Tropic of Cancer. Therefore the temperature is very high in the northern parts of the India. Due to this high temperature, low pressure conditions prevail over northern part of India.
• The southern parts of India has moderate weather conditions because of its locations nearer to sea. The Mean maximum temperature have varies from 26⁰ C to 35⁰ High pressure develops here due to low temperature comparatively to the north India.
• Because of the atmospheric pressure conditions, the winds blow form south west to north east direction in Arabian Sea and Bay of Bengal. They bring pre monsoon showers to the west coastal areas during May. There are a few thunder showers called ‘Mangoshowers’ which helps in quick ripening of mangoes along the coast of Kerala and Karnataka. 
• North Eastern part of India also experiences local storms called ‘Norwesters’. These thunder storms are called as Kalbaisakhi (Calamity of the month of Baisakh) in Punjab. Strong hot winds blow during day time over northern and northwest parts of India are called as ‘Loo winds’.

2. South West Monsoon (June to September)

• The high temperature givers rise to low pressure and by the end of May a large area of low pressure is formed over the north west part of the country. At the same time, the oceans become cool and a high pressure area develops over the oceans. We know that wind always blow from high pressure to low pressure.  Hence the winds blow from oceans towards the land of India.
• These winds blow from south East directions. When they cross the equator, they get deflected and blow as South West Monsoon. These winds are moisture laden winds because they originate from Indian ocean. When they approach the Southern part of Kerala they give rain with violent thunderstorms indicating the onset of the monsoon and lightning.  This phenomenon is often termed as the ‘monsoon burst’.

1. Arabian Sea Branch

• The more powerful Arabian Sea branch of monsoon wind brings heavier rainfall. Blowing from the Arabian Sea, the first part of the wind first strikes against the Western Ghats. This moisture laden wind is forced to ascend the slopes, condenses and gives heavy rainfall to western coastal region. 
• Mumbai gets a heavy rainfall of over 150cms as it lies on the windward side of Western Ghats while Pune gets less than 50cms of rainfall as it lies on the leeward side (rain shadow) of the Western Ghats.
• The second part of this wind blow through the vindhya-satpura ranges and strikes against the Rajmahal hills and cause heavy rainfall in the Chotanagpur Plateau region.
• The third part of this wind moves towards Rajasthan where the Aravalli Mountains stand parallel to the direction of this wind. Hence it is not able to strike against the mountain and does not give any rain to Rajasthan. This is the reason why a part of Western Rajasthan remains to be a desert.
• This wind then reaches Himachal Pradesh and combines with the Bay of Bengal branch. It gets obstructed by the Shiwalik hills and gives a good rainfall to the foot hills of this region.

1. Bay of Bengal Branch

• This branch of monsoon, blowing from the Bay of Bengal is ‘moisture bearing wind’. It strikes against the Kasi, Garo, and Jaintia Hills. This moisture laden wind takes a sudden rise over the funnel shaped hills and causes heavy rainfall in Mawsynram, which receives the highest rainfall in India.
• A part of this branchy gets deflected by the Himalayas and moves towards the west giving rain to the Gangetic   As it moves further westwards, it loses its moisture content and gives scanty rainfall to Punjab and Haryana.

 Finally this Wind meets the Arabian Sea branch of monsoon wind at the foot hills of the Himalayas and gives heavy rainfall along the Siwaliks. Tamil Nadu remains dry during this period because it lies in the rain shadow area, of the Arabian Sea branch monsoon and it lies parallel to the Bay of Bengal branch.

3. North East Monsoon (October to November)

• The south West Monsoon begins to retreat from the Northern India by second week of September because of the apparent movement of the sun towards tropic of Capricorn. The landmass of India starts losing heat and there is a fall in the temperature.
• But the sea is still in warm condition. High Pressure develops over the land and low pressure over the sea. Therefore wind blows from high pressure to low pressure that is from land to sea. It is cold dry wind and gives no rainfall to land mass. 
• But, when it crosses they Bay of Bengal, it absorbs moisture and gives heavy rain to the Coromandal coast. So Andhra Pradesh and Tamil Nadu get heavy rainfall during winter. There are frequent cyclones formed in the Bay of Bengal and they cause damage to life and property along the Coromandal coast.

4. Winter (December to February)

• During winter, the sun is overhead in the Tropic of Capricorn. The land Mass becomes cold in North India where the day mean temperature remains below 21⁰  No obvious difference is found in the temperature during day and night.
• In the meantime high pressure develops in the northwestern part of India due to the prevalence of low-temperature. In contrast to this, low pressure area forms in South India, that it both in Arabian Sea and Bay of Bengal. Consequently the winds blow from the high pressure area of northwest India towards South India.  These winds are called the ‘Retreating monsoon winds’ which blow from land to sea and do not cause much rain fall. 
• But these winds absorb some moisture gives winter rainfall to Tamil Nadu and South Andhra Pradesh. This is the main characteristics feature of Retreating monsoon. During this period, a low pressure depression originates over the Mediterranean Sea and travels eastwards across Iran and Afghanistan and reaches India. This low pressure depressikon is called ‘Western disturbance’.
• The Jet stream plays a dominant role in bringing this disturbance to India. This disturbances causes rainfall in Punjab, Haryana and Himachal Pradesh which is very useful for the cultivation of wheat. It also brings snow fall in the hills of Jammu and Kashmir.

FEATURES OF THE MONSOON

1. i) Uneven distribution of Rainfall during the year.
2. ii) Influence of Mountains

iii) Tropical Cyclone

1. iv) Erratic nature of the Rainfall
2. v) Monsoon rains have great effect on the country’s economy

• On the basis of the amount of rainfall our country can be divided into four rainfall regions as follows :

1) Region of very heavy rainfall

• Areas with over 300cm of rain are the southern slopes of the Eastern Himalayas, Assam, Bengal and the West Coast Region comprising the Konkan and the Malabar Coast.

2. Regions of heavy rainfall

• Areas with rainfall between 200 to 300 cm are the Middle Ganga Valley, Western Ghats, Eastern Maharashtra, Madhya Pradesh and Odisha

3. Regions of moderate rainfall

• Areas with 100 to 200 cam of rainfall are the Upper Ganga valley, Eastern Rajasthan and Punjab, Southern Deccan comprising the plateau regions of Karnataka, Andhra Pradesh and Tamil Nadu.

4. Regions of Scanty rainfall

• Areas with less than 50 cm are the northern part of Kashmir, western Rajasthan, southern Punjab and regions of the Deccan in the rain shadow of the Western Ghats.