Climate and Vegetation
The Equatorial type climate, in which the temperature remains high all the year round but does not vary much, produces hot, wet forests.
The Tropical type climate produces grasslands which are found on either side of the equatorial belt where the rainfall usually occurs soon after the sun has been shining vertically while the dry season occurs in the colder part of the year.
The lowlands along the Tropic of Cancer lie mainly in the high-pressure belt just outside the Tropics. The Trade Winds blow away from these lowlands towards the Equator and the Westerly winds blow away from them towards the Poles. There are, therefore, no winds to bring rain to this region. Some of these lowlands are dry because these are very very far from the sea, like centre of Asia. There are few clouds and very little rain with the result that the sun’s rays strike straight on the ground and make the days very hot.
The temperature of the ocean varies much less than that of land because (i) water has a higher specific heat than land with the result that it both absorbs and loses heat slowly as compared to land; and (ii) due to large surface of water at sea more evaporation occurs than on land. Evaporation causes cooling and this results in the sea having a lower temperature than that on land.
We may divide India into two parts for the purpose of climatological studies: (1) peninsular India and (2) Northern India. Peninsular India has the characteristic of tropical climate where “the temperature is uniformly high and seasonal variation relatively low”.
The climatic conditions in Northern India have no general similarity. This region lies beyond the Tropic of Cancer. The Western part of it includes East Punjab and Rajasthan where air is devoid of moisture and it is hot in summer and very cold in winter. The eastern part of this region includes U.P., Bihar, Assam and West Bengal. Here winter is mild and summer is very hot with plenty of moisture in the air.
These climatic conditions are however, disturbed by two Monsoon Currents—the South West Monsoon and the North-East Monsoon. The South-West Monsoon causes heavy rainfall in Assam, West Bengal and U.P. It begins to retreat from Northern India in early October and this retreat is completed by mid-December. During this retreat period the weather in Northern India becomes dry.
The North-East monsoons begin in January and last till March. These winds cause light rain in Northern India, particularly in the Punjab plains. This scanty rainfall is very important for Rabi crops.
Vegetation: Agriculture is the most important occupation of the people of India. In Northern India, typical monsoon land crops are grown such as rice in Bengal with its warm and humid climate; wheat and maize in Northern plains, Punjab and U.P.; jute in Bengal and Assam and tea in Assam.
In Peninsular India where regur or black cotton soil is found and sufficient moisture available, cotton is grown. It is the chief crop of the Deccan Peninsula—Mumbai and Berar being the chief producers. Coffee is grown on the Nilgiris in the South.
Climatic Effect: India has on the whole monsoon-tropical climate: ‘Monsoon—lands are dominated by the winds from sea to land in summer—the wet season and by winds from land to sea in winter—the dry season.’ This type of climate is not very conducive to health and vigour. Man’s well-being in such a climate depends largely on rainfall. The agricultural products do not grow if the monsoon fails and famine conditions break out. This dependence on rain, however, is not absolute owing to development of irrigation by means of projects, canals, wells etc.
The desert type climate is hot and dry. The rainfall is scanty, not more than 10 inches a year. The day and night temperatures vary to much extent. The evenings and afternoons are marked by hot dust storms.
The regions lie mainly in the high-pressure belts just outside the Tropics. The Trade Winds blow away from them towards the Equator and the Westerly Winds blow away from them towards the Poles. There are no winds which bring rain to this region and the climate remains hot and dry.
Mediterranean Climate
It is the type of climate experienced by the lands bordering the Mediterranean Sea, and also by other regions, in both hemispheres, situated in a similar geographical position. The characteristic features are warmth of the summer, mildness of the winter, and ample sunshine.
The entire west coast of the United States has Mediterranean type of climate because this region gets winter rainfall from “Westerlies” winds.
Irrigation
Methods of Irrigation: The various systems of irrigation used in India are: (1) Canals; (2) Wells; (3) Tube-wells; and (4) Tanks.
Canals: Canals are the most important of the systems of irrigation in India because:
(i) the rivers are snow-fed and never run dry; (ii) the plain has a soft and alluvial soil, so canals can be easily dug; (iii) the rainfall is insufficient for irrigation and wells alone cannot satisfy the needs of agriculturists.
Of the total irrigated land in India, 40 per cent is irrigated by canals.
Wells: Wells are found all over India but these are largely used in Uttar Pradesh, Punjab, Haryana and Bihar. They are also used in Tamil Nadu, Maharashtra and Rajasthan. The reason for irrigation by wells is that the soil is porous and after a rainfall, water is stored up below the soil, and wells can be easily sunk.
Tube-wells: Irrigation by tube-wells has become very popular these days. Tube-wells are worked by electric power. These are much deeper than the ordinary wells. Due to shortage of power, the agriculturists do face the difficulty in running the tube-wells as and when they require but the prosperous ones are making use of the diesel engines for the purpose.
Tanks: Tanks are used in the Deccan plateau—especially in Tamil Nadu, Andhra Pradesh, Karnataka and in some parts of Madhya Pradesh. They are made by filling natural hollows with water or by building dams across the river valleys. As the soil is rocky in these areas, it is not easy to sink wells. The soil is not porous and the rain water flows off; Canals cannot be constructed as the rivers are not snow-fed. So the tanks are the chief means of irrigation in the Deccan plateau.
Volcanoes and Earthquakes
Volcanoes: By the pressure of the earth’s crust the hot matter or lava in the interior of the earth is pressed down. It gushes out through a crack or a hole when it finds a weak spot in the crust and begins to accumulate round it. By and by it cools down and solidifies and in the course of several years these accumulated layers of lava build up a conical mountain. Such lava mountains are called volcanoes.
Volcanoes are also formed when rain or sea water percolates in the soil and sinks deep down into the earth where it is converted into steam by the internal heat and forces its way out of the crust bringing with it large quantity of lava etc.
Earthquakes: (i) When an active volcano bursts with great force or when a dormant volcano erupts into activity, the surrounding areas feel tremors and earthquake is caused. (ii) When the interior part of the earth cools down and contracts, the outer crust cracks or a part of it actually drops down causing earthquake. (iii) Sometimes water percolates deep down into the earth and is converted into steam on account of internal heat. This steam forces its way out by expanding and thus causes earthquake shocks.
Fold and Block Mountains
Fold Mountains: These are formed as a result of series of earthquakes by which in course of a long time, rocks are folded up above the general level and the agents of denudation start to wear them away. The Himalayas, the Andes, the Alps are example of Fold Mountains.
Block Mountains: the formation of mountains when a mass of land is pushed up between several cracks, is known as Block Mountains as shown in the figure below. The narrow piece of the crust led down between two parallel cracks forms what is called “Rift Valley”.
Mountain Ranges
Himalayas: The Himalayan ranges stretch for about 2400 km from the eastern extremity of Assam to the western limit of Kashmir. Their width varies from 150 km to 450 km. These are fold mountains and consist of long lines of folded ranges.
Arvalies: It stretches from Gujarat in the west to Delhi in the north.
Indian Plateau: It is the table-land region of the Deccan lying south of the Indo-Gangetic Plain. It is bounded on the north by the ranges of Vindhyas and the Satpuras running east to west.
Vindhyas and Satpura: The Vindhyas lie north of the Narbada Valley, whereas the Satpuras Range lies south. Satpura ranges are an example of Volcanic mountains.
Western Ghats: In the west, the plateau is margined by the Western Ghats which rise abruptly from the Malabar and the Konkan coasts and run parallel to the sea coast with an average height of 1200 metres.
Eastern Ghats: Towards the east are broken Eastern Ghats which descend to the low-lands of the Coromandal coast and are broken by a number of rivers, the most important of which are the Mahanadi, Godavari, Krishna, Penner and Cauvery. These rivers flow south-east across the plateau to the Bay of Bengal.
The Equatorial type climate, in which the temperature remains high all the year round but does not vary much, produces hot, wet forests.
The Tropical type climate produces grasslands which are found on either side of the equatorial belt where the rainfall usually occurs soon after the sun has been shining vertically while the dry season occurs in the colder part of the year.
The lowlands along the Tropic of Cancer lie mainly in the high-pressure belt just outside the Tropics. The Trade Winds blow away from these lowlands towards the Equator and the Westerly winds blow away from them towards the Poles. There are, therefore, no winds to bring rain to this region. Some of these lowlands are dry because these are very very far from the sea, like centre of Asia. There are few clouds and very little rain with the result that the sun’s rays strike straight on the ground and make the days very hot.
The temperature of the ocean varies much less than that of land because (i) water has a higher specific heat than land with the result that it both absorbs and loses heat slowly as compared to land; and (ii) due to large surface of water at sea more evaporation occurs than on land. Evaporation causes cooling and this results in the sea having a lower temperature than that on land.
We may divide India into two parts for the purpose of climatological studies: (1) peninsular India and (2) Northern India. Peninsular India has the characteristic of tropical climate where “the temperature is uniformly high and seasonal variation relatively low”.
The climatic conditions in Northern India have no general similarity. This region lies beyond the Tropic of Cancer. The Western part of it includes East Punjab and Rajasthan where air is devoid of moisture and it is hot in summer and very cold in winter. The eastern part of this region includes U.P., Bihar, Assam and West Bengal. Here winter is mild and summer is very hot with plenty of moisture in the air.
These climatic conditions are however, disturbed by two Monsoon Currents—the South West Monsoon and the North-East Monsoon. The South-West Monsoon causes heavy rainfall in Assam, West Bengal and U.P. It begins to retreat from Northern India in early October and this retreat is completed by mid-December. During this retreat period the weather in Northern India becomes dry.
The North-East monsoons begin in January and last till March. These winds cause light rain in Northern India, particularly in the Punjab plains. This scanty rainfall is very important for Rabi crops.
Vegetation: Agriculture is the most important occupation of the people of India. In Northern India, typical monsoon land crops are grown such as rice in Bengal with its warm and humid climate; wheat and maize in Northern plains, Punjab and U.P.; jute in Bengal and Assam and tea in Assam.
In Peninsular India where regur or black cotton soil is found and sufficient moisture available, cotton is grown. It is the chief crop of the Deccan Peninsula—Mumbai and Berar being the chief producers. Coffee is grown on the Nilgiris in the South.
Climatic Effect: India has on the whole monsoon-tropical climate: ‘Monsoon—lands are dominated by the winds from sea to land in summer—the wet season and by winds from land to sea in winter—the dry season.’ This type of climate is not very conducive to health and vigour. Man’s well-being in such a climate depends largely on rainfall. The agricultural products do not grow if the monsoon fails and famine conditions break out. This dependence on rain, however, is not absolute owing to development of irrigation by means of projects, canals, wells etc.
The desert type climate is hot and dry. The rainfall is scanty, not more than 10 inches a year. The day and night temperatures vary to much extent. The evenings and afternoons are marked by hot dust storms.
The regions lie mainly in the high-pressure belts just outside the Tropics. The Trade Winds blow away from them towards the Equator and the Westerly Winds blow away from them towards the Poles. There are no winds which bring rain to this region and the climate remains hot and dry.
Mediterranean Climate
It is the type of climate experienced by the lands bordering the Mediterranean Sea, and also by other regions, in both hemispheres, situated in a similar geographical position. The characteristic features are warmth of the summer, mildness of the winter, and ample sunshine.
The entire west coast of the United States has Mediterranean type of climate because this region gets winter rainfall from “Westerlies” winds.
Irrigation
Methods of Irrigation: The various systems of irrigation used in India are: (1) Canals; (2) Wells; (3) Tube-wells; and (4) Tanks.
Canals: Canals are the most important of the systems of irrigation in India because:
(i) the rivers are snow-fed and never run dry; (ii) the plain has a soft and alluvial soil, so canals can be easily dug; (iii) the rainfall is insufficient for irrigation and wells alone cannot satisfy the needs of agriculturists.
Of the total irrigated land in India, 40 per cent is irrigated by canals.
Wells: Wells are found all over India but these are largely used in Uttar Pradesh, Punjab, Haryana and Bihar. They are also used in Tamil Nadu, Maharashtra and Rajasthan. The reason for irrigation by wells is that the soil is porous and after a rainfall, water is stored up below the soil, and wells can be easily sunk.
Tube-wells: Irrigation by tube-wells has become very popular these days. Tube-wells are worked by electric power. These are much deeper than the ordinary wells. Due to shortage of power, the agriculturists do face the difficulty in running the tube-wells as and when they require but the prosperous ones are making use of the diesel engines for the purpose.
Tanks: Tanks are used in the Deccan plateau—especially in Tamil Nadu, Andhra Pradesh, Karnataka and in some parts of Madhya Pradesh. They are made by filling natural hollows with water or by building dams across the river valleys. As the soil is rocky in these areas, it is not easy to sink wells. The soil is not porous and the rain water flows off; Canals cannot be constructed as the rivers are not snow-fed. So the tanks are the chief means of irrigation in the Deccan plateau.
Volcanoes and Earthquakes
Volcanoes: By the pressure of the earth’s crust the hot matter or lava in the interior of the earth is pressed down. It gushes out through a crack or a hole when it finds a weak spot in the crust and begins to accumulate round it. By and by it cools down and solidifies and in the course of several years these accumulated layers of lava build up a conical mountain. Such lava mountains are called volcanoes.
Volcanoes are also formed when rain or sea water percolates in the soil and sinks deep down into the earth where it is converted into steam by the internal heat and forces its way out of the crust bringing with it large quantity of lava etc.
Earthquakes: (i) When an active volcano bursts with great force or when a dormant volcano erupts into activity, the surrounding areas feel tremors and earthquake is caused. (ii) When the interior part of the earth cools down and contracts, the outer crust cracks or a part of it actually drops down causing earthquake. (iii) Sometimes water percolates deep down into the earth and is converted into steam on account of internal heat. This steam forces its way out by expanding and thus causes earthquake shocks.
Fold and Block Mountains
Fold Mountains: These are formed as a result of series of earthquakes by which in course of a long time, rocks are folded up above the general level and the agents of denudation start to wear them away. The Himalayas, the Andes, the Alps are example of Fold Mountains.
Block Mountains: the formation of mountains when a mass of land is pushed up between several cracks, is known as Block Mountains as shown in the figure below. The narrow piece of the crust led down between two parallel cracks forms what is called “Rift Valley”.
Mountain Ranges
Himalayas: The Himalayan ranges stretch for about 2400 km from the eastern extremity of Assam to the western limit of Kashmir. Their width varies from 150 km to 450 km. These are fold mountains and consist of long lines of folded ranges.
Arvalies: It stretches from Gujarat in the west to Delhi in the north.
Indian Plateau: It is the table-land region of the Deccan lying south of the Indo-Gangetic Plain. It is bounded on the north by the ranges of Vindhyas and the Satpuras running east to west.
Vindhyas and Satpura: The Vindhyas lie north of the Narbada Valley, whereas the Satpuras Range lies south. Satpura ranges are an example of Volcanic mountains.
Western Ghats: In the west, the plateau is margined by the Western Ghats which rise abruptly from the Malabar and the Konkan coasts and run parallel to the sea coast with an average height of 1200 metres.
Eastern Ghats: Towards the east are broken Eastern Ghats which descend to the low-lands of the Coromandal coast and are broken by a number of rivers, the most important of which are the Mahanadi, Godavari, Krishna, Penner and Cauvery. These rivers flow south-east across the plateau to the Bay of Bengal.
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