The Climate of India
India has tropical monsoon type of climate. It is greatly influenced by the presence of the Himalayas in the north as they block the cold the cold air masses from Central Asia. It is because of them only that the monsoons have a watershed in India.
The Tropic of Cancer divides India into two almost equal climatic zones, namely, the northern zone and the southern zone. The warm temperate or the subtropical climate of the northern zone gives it cold winter seasons and the hot summer
The southern tropical climatic zone is warmer than the north and does not have a clear-cut winter
The northern zone does not have the midday sun vertically overhead during any part of the year; the southern zone has the midday sun almost vertically overhead at least twice every
Climate Seasons in India
In India, the year can be divided into four seasons, resulting from the monsoons which occur mainly due to the differential heating of land and movement of the sun’s vertical
The vertical rays of the sun advance towards Tropic of Cancer from mid-March, due to which hot and dry weather arrives. As temperatures rise over most of northern and Central India, a vast trough of low pressure is created. The highest temperature experienced in South is in April while in North it is in May and
This part of the year is marked by a dry spell and the north-western parts of the country experience hot, dry winds, called loo. In this period, the country also experience storms / dust storms at various
Tornado like dust storms in Punjab and Haryana, called ‘Andhis’ in UP and ‘Kalbaisakhis’ in West Bengal. They involve strong convectional movements causing some
The ‘Norwesters’ originate over the Chhotanagpur Plateau and blow in the north-east direction which brings about 50 cm of
rainfall in Assam and about 10 cm rainfall in West Bengal and Orissa. This rainfall is very useful for Assam tea and spring rice crops of West
Similarly, ‘Cherry Blossoms’ are there in Karnataka, beneficial to coffee plantation and
‘Mango showers’ in elsewhere South India, which are beneficial to mango crops.
This weather is followed by hot, wet weather from June to September. In May, the south – west monsoon sets in. The normal dates of onset of the monsoon are May 20 in the Andaman and Nicobar Islands, June 3 in the Konkan, June 15 in Kolkata and June 29 in
The south – west monsoon enters the country in two currents, one blowing over the Bay of Bengal and the other over the Arabian Sea. This monsoon causes rainfall over most of the country (except Tamil Nadu and Thar Desert area). The W monsoon entering from Western Ghats causes heavy rainfall over Kerala coast, but Tamil Nadu falls on the leeward side. In the Thar area, the winds blow parallel to the Aravallis and do not cause rain. The Bay of Bengal current causes heavy rainfall in the north east parts of the country and a part of it turns west along the Himalayas over the Indo-Gangetic plains causing rainfall in this region. But the Bay of Bengal current, by the time it reaches W Rajasthan, runs out of moisture.
The Bay of Bengal branch after crossing the deltaic region enters the Khasi valley in Meghalaya and gets entrapped in it due to funnel shape of the region. It strikes Cherrapunji in a perpendicular direction causing heavies rainfall in Mawsinram (Approx. 1400 cm).
From mid-Sept to mid-Dec, the monsoon retreats. As the sun’s vertical rays start shifting towards the Tropic of Capricorn, the low pressure area starts moving south and winds finally start blowing from land to This is called north-east monsoon. The withdrawal of monsoon is a much more gradual process than its onset. It causes rainfall in Tamil Nadu as the winds pick some moisture from Bay of Bengal. This explains the phenomenon why Tamil Nadu remains dry when the entire country receives rain and why it gets rain when practically the entire country is dry.
Almost all the precipitation in India is caused by the monsoons and it is primarily orographic in nature. Cyclonic storms provide only a little rain, mainly in the north.
The cold and dry weather starts in early December. In this, the average temperature in south is 24-25c, and while in the north is 10-15c. In the latter part of December and in January, the dry spell is broken by the westerly depressions (temperate cyclones) from Mediterranean Sea, which causes some rain in north-west India
Climatic Regions of India
India can be divided into a number of climatic regions.
Tropical Rain Forests in India : Found in the west coastal plains, the Western Ghats and parts of Assam. Characterized by high temperatures throughout the year. Rainfall, though seasonal, is heavy- about 200 cm annually during May-November.
Tropical Savanna Climate : In most of the peninsula region except the semi-arid zone in the leeward side of the Western Ghats. It is characterized by long dry weather throughout winter and early summer and high temperature (above 18.2c); annual rainfall varies from 76 cm in the west to 150 cm in the
Tropical Semi-Arid Steppe Climate : It prevails in the rain-shadow belt running southward from Central Maharashtra to Tamil Nadu in the leeward side of the Western Ghats and the Cardamom Hills. It is characterized by low rainfall which varies from 38 cm to 80 cm, high temperature between 20 and 30.
Tropical and Subtropical Steppes : Large areas in Punjab, Haryana and Kutch region. Temperature varies from 12-35c. The maximum temperature reaches up to 49c. The annual rainfall, varying from 30.5-63.5 cm, is also highly erratic
Mountain Climate : Such type of climate is seen in mountainous regions which rise above 6,000 m or more such as the Himalayas and the Karakoram Range.
Humid Subtropical Climate with Dry Winters : This area includes south of the Himalayas, east of the tropical and subtropical steppes and north of tropical savannah. Winters are mild to severe while summers are extremely hot. The annual rainfall varies from 63.5 cm to more than 254 cm, most of it received during the south west monsoon
Tropical desert : This climate extends over the western parts of Banner, Jaisalmer and Bikaner districts of Rajasthan and parts of Kutch. It is characterized by scanty rainfall (30.5 cm), which is highly erratic. Rains are mostly in the form of cloud-burst. Mean monthly temperature is uniformly high (about 35c).
A joint venture of Punjab, Haryana and Rajasthan, the Bhakhra Nangal Project is India’s biggest multi-purpose river valley project so far completed at a cost of Rs. 236 crores. It consists of a straight gravity dam, 518 metre long and 226 metre high across the Sutlej at Bhakhra. The Bhakhra dam impounds 986•8 crore cubic metres of water. The canal system of the project is now irrigating 14•8 lakh hectares. It generates 1204 MW. electricity.
2. Chambal Project (Madhya Pradesh and Rajasthan)
The Chambal Project is being jointly executed by Madhya Pradesh and Rajasthan. In the first stage, the Gandhi Sagar dam and its 115 MW power station and the Kota barrage were completed. The Rana Pratap Sagar dam with a power house of 172MW. capacity was constructed in the second stage. The third stage comprises the construction of the Jawahar Sagar dam and a 99 MW. power station. With the completion of all the three stages, the project will generate 386MW of power.
3. Damodar Valley Project (Jharkhand and West Bengal)
The Damodar Valley Project was conceived for the unified development of irrigation, flood control and power generation in West Bengal and Jharkhand. The project is administered by the Damodar Valley Corporation (DVC), established in 1948. The irrigation potential of the project is about 5•51 lakh hectares and its installed power generating capacity is 1181MW. It is designed on the lines of Tennesse Valley Authority (TVA) in the U.S.A.
4. Farakka Barrage (West Bengal)
It consists of a barrage across the Ganga at Farakha; another barrage at Jangipur across the Bhagirathi, a 39 Km. long feeder canal taking off from the right bank of the Ganga, at Farakka and tailing into the Bhagirathi below the Jangipur Barrage and a road-cum-rail bridge over the Farakka barrage have already been completed.
The basic aim of the Farakka barrage is to preserve and maintain Calcutta port and to improve the navigability of the Hooghly river. Specifically, the object of Farrakka is to use about 40‚000 cusecs of water out of the water stored in the dam to flush the Calcutta port which is getting silted up.
5. Indira Gandhi Canal
It is one of the biggest irrigation projects in the world, begun in 1958 as Rajasthan Canal. It is a bold venture of bringing irrigation to a desert area. It will provide irrigation facility to N-W Region of Rajasthan a part of Thar desert. The Project which will use water from the Pong dam consists of 215 km long Rajasthan feeder canal (with the first 178 km in Punjab and Haryana and remaining 37 km in Rajasthan) and the 445 km long Rajasthan main canal lying entirely in Rajasthan. The project will ultimately irrigate about 14•5 lakh
6. Hirakud Project (Orissa)
The 4801•2 metre long main Hirakud dam in Orissa is on the river Mahanadi. It is the world’s longest dam. The project irrigates an area of 11•98 lakh hectares. Its present installed power generation capacity is 27•2 MW.
7. Kakrapara Project (Gujarat)
It is on the river Tapti, 80 km upstream of Surat. It is being built by the Gujarat Government. A 621 metre long and 14 metre high weir near Kakrapara in Surat district was completed in 1963.
8. Koyna Project (Maharashtra)
It is on the river Koyna and has been built by the Government of Maharashtra. It comprises the construction of a 208 ft. high dam.
9. Nagarjun Sagar Project (Andhra Pradesh)
It is an undertaking of the Government of Andhra Pradesh for utilizing the water of the Krishna river. It was inaugurated on Aug. 4, 1967. It is situated near Nandikonda Village in Miryalgude Taluk of Nalgonda district. The Nagarjun Sagar Project comprises the construction of a 1450 metre long and 92 metre high dam. The dam has been completed. The project will ultimately irrigate about 8•95 lakh hectares.
10. Rihand Project (Uttar Pradesh)
This project has been completed by the U.P. Government and comprises construction of a concrete gravity dam across the Rihand river in Mirzapur district (U.P.) and a power house at Pipri and necessary transmission lines.
11. Thien Dam (Punjab)
A 147 metre high dam built by the Punjab Government at Thien village across the Ravi 25 km. upstream of Madhopur head works. It will irrigate 8 lakh hectares land and generate 600 MW. power. Renamed as Ranjit Sagar Dam it was dedicated to the nation on March 4, 2001 by Prime Minister Atal Behari Vajpayee.
12. Tungbhadra Project (Andhra Pradesh)
It is a joint undertaking by the Government of Andhra Pradesh and Karnataka. It comprises a 2441 metre long and 49•38 metre high dam across the river Tungbhadra near Malipuram. It irrigates about 10•22 lakh hectares land.
13. Ukai Project (Gujarat)
It is a Project of the State of Gujarat. It consists of a 4928 metre long and 68•6 metre high dam across the River Tapti near Ukai village, 116 Km. upstream of Surat town. The Project will irrigate 1•53 hectares land and generate 300MW of power.
14. Tehri Dam (Uttarakhand)
Being constructed on Bhagirathi in Uttarakhand with the assistance of the Soviet Union (now Russia) is now in hot waters. Ecologists believe it will be a disaster to the local people.