7TH GEO N EM
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Life in the Deserts Class 7 Notes Geography Chapter 10

 

Life in the Deserts Class 7 Notes Social Science Geography Chapter 10

Deserts are characterised by low rainfall, scanty vegetation and extreme temperatures.

Depending on the temperature, there can be hot deserts or cold deserts.

The Hot Desert – Sahara

  • The Sahara Desert in Africa is the world’s largest hot desert.
  • It touches 11 countries and has got gravel plains and elevated plateaus with a bare rocky surface.
  • The climate of Sahara is scorching hot and parched dry with temperature as high as 50° C.
  • The nights are freezing cold with the temperature nearing zero degrees.
  • Vegetation in the Sahara Desert includes cactus, date palms and acacia. Camels, hyenas, jackals, foxes, scorpions, snakes and lizards are the main animal species found here.
  • Despite its harsh climate, Sahara is inhabited by various groups of people. The main groups are Bedouins and Tuaregs.
  • The oasis in the Sahara and the Nile Valley in Egypt supports the settled population.
  • The discovery of oil is constantly transforming this region. Other important minerals found here are iron, phosphorus, manganese and uranium.
  • More and more nomadic tribes are taking to city life.

The Cold Desert – Ladakh

  • Ladakh is a cold desert lying in the Great Himalayas, on the eastern side of Jammu and Kashmir.
  • The altitude in Ladakh varies from 3,000 m in Kargil to more than 8,000 m in the Karakoram.
  • The area experiences freezing winds and burning hot sunlight.
  • Due to high aridity, the vegetation is sparse. Groves of willows and poplars are seen in the valleys.
  • The animals of Ladakh are wild goats, wild sheep, yak and special kinds of dogs.
  • The animals are reared as they provide milk, meat and hides.
  • The population consists of either Muslims or Buddhists.
  • Some famous Buddhist monasteries are Hemis, Thiksey, Shey and Lamayuru.
  • In the summer season, the people are busy cultivating barley, potatoes, peas, beans and turnips.
  • Tourism is a major activity with several tourists streaming in from within India and abroad.
  • People of Ladakh have over the centuries learnt to live in balance and harmony with nature.
  • Pashmina wool of this region is famous.
  • Leh and Kargil are the main towns in Ladakh.

The desert areas of the world are characterised by low rainfall, scanty vegetation and extreme temperatures. Depending on the temperatures there are hot deserts as well as cold deserts.

Sahara is a hot desert covering a large part of North Africa and Ladakh is a cold desert lying in the Great Himalayas on the eastern side of Jammu and Kashmir in India.

Sahara is the world’s largest desert.

The Sahara desert touches eleven countries—Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Sudan, Tunisia and Western Sahara.

The Sahara desert is the vast stretches of sand. There are also gravel plains and elevated plantains with a bare rocky surface.

The climate of the Sahara desert is scorching hot and parched dry. The rainy season is very short. The day temperature may soar as high as 50°C. But nights may be freezing cold.

Vegetation in the Sahara desert is comprised of cactus, date, palms and acacia. Date palms are found near an oasis. So far animals are concerned camels, hyenas, jackals, foxes, scorpions, several varieties of snakes and lizards are found in this dessert.

Various groups of people such as the Bedouins and Tuaregs live in the Sahara desert. These groups are a nomadic tribe and they rear goats, sheep, camels and horses. They get milk and hides from these animals. These nomadic tribes wear heavy robes to protect themselves from dust storms and hot winds.

People get water from the oasis in the Sahara desert and the Nile valley in Egypt. They grow crops like rice, wheat, barley and beans.

The Sahara desert is undergoing fast change due to the discovery of oil in Algeria, Libya and Egypt. Other minerals found here are iron, phosphorus, manganese and uranium.

Trucks are now used in the salt trade.

The nomadic herdsmen with a change of time are now migrating to cities for better job opportunities in oil and gas operations.

Ladakh is a cold desert. The Karakoram range in the north and the Zanskar mountains in the south enclose it. Several rivers flow through Ladakh. Several glaciers are found here, for example, the Gangotri glacier.

The climate of Ladakh is extremely cold and dry. The day temperatures in summer are just above zero degree and the night temperatures are below – 30°C. This desert receives very little rainfall. There is always a chance of both sunstroke and frostbite.

Ladakh has poor vegetation. There are scanty patches of grasses. Groves of willows and poplars are seen in the valleys.

Several species of birds such as robins, redstarts, Tibetan snow cock, raven and hoopoe are found here. The animals of Ladakh are wild goats, wild sheep, yak and special kinds of dogs.

People living in this desert are either Muslims or Buddhists.

Famous Buddhist monasteries are Hemis, Thiksey, Shey and Lamayuru.

People grow crops like barley, potatoes, peas beans and turnips during the summer season. During the winter months they are engaged in festivities and ceremonies.

The women of Ladakh are hardworking. They can manage indoor and outdoor activities skilfully.

Leh is the capital of Ladakh.

Ladakh is a famous tourist place. The tourists from within India and abroad like to visit the gompas.

Ladakh is being modernised fast. But people are very conscious here. They know the ways to live in balance and harmony with nature.

Desert: It refers to an arid area characterised by extremely high or low temperatures with poor vegetation.

Oasis: It is an area in the desert where there is water and where plants grow.

Shahtoosh: It is kind of wool obtained from Chiru or the Tibetan antelope.

Gangri: It is a glacier found in Ladakh.

Tuaregs: These are nomads of the Sahara desert.

Bedouins: These are nomads of the Sahara desert.

Khapa-chan: Ladakh is also known by this name. It means snow land.

Life in the Temperate Grasslands Class 7 Notes Geography Chapter 9

 

Life in the Temperate Grasslands Class 7 Notes Social Science Geography Chapter 9

Grassland is a region where grasses from the dominant type of plant life.

Depending upon the climate conditions, grasslands can be divided into two categories, the Temperate Grasslands and the Tropical Grasslands.

The Prairies

  • Prairies are the Temperate Grassland found in North America. They are bound by the Rocky Mountains ‘ the West and the Great Lakes in the East.
  • For the most part, Prairies are tree-less but, near the low-lying area’s woodlands can be found. The prairies are bound by the Rocky Mountains in the West and the Great Lakes in the East.
  • Prairies cover major parts of the USA and Canada.

Climate

  • Climate is of continental type with extreme temperature ie with warm summers and very cold winters.
  • The annual rainfall is moderate and is ideal for the growth of grass.

Flora and Fauna

  • Prairies are practically tree-less but the places where water is available, trees such as willows, alders and poplars grow.
  • Places that receive rainfall of over 50 cm, are suitable for farming as the soil is fertile.
  • The prairies are known as the ‘Granaries of the world’ because surplus wheat is produced here.
  • Bison or American buffalo is the most important animal.

People

  • Large-scale cattle farms called ranches are looked after by the sturdy men called cowboys.
  • Large scale farming with modern technology is done here.

The Velds

  • The Temperate Grasslands of South Africa are called the velds.
  • Velds are rolling plateaus with varying heights ranging from 600 m to 1100 m.
  • It is bound by the Drakensberg Mountains on the east.

Climate

  • The welds have a mild climate due to the influence of the Indian Oceans.
  • Here the summers are short and warm.
  • The velds receive rainfall mainly in the summer months from November to February.
  • Winters are cold and dry. Temperature varies between 5°C and 10°C and July is the coldest month.

Flora and Fauna

  • Vegetation cover is sparse.
  • Red grass grows in bush velds.

People

  • Velds are known for cattle rearing and mining.
  • The main crops are maize, wheat, barley, oats and potatoes.
  • The velds have a rich reserve of minerals.
  • Iron and steel industry has developed where coal and iron are present.
  • Johannesburg is known as the gold capital of the world.

Grassland is a region where grasses form the dominant type of plant life. Grasslands make up almost a quarter of the total land surface.

The world’s grasslands are divided into two categories: those that occur in the temperate region and those that occur in the tropical region.

The prairies are the temperate grasslands in North America. They are bound by the Rocky Mountains in the west and the Great Lakes in the East.

The prairies are located in the heart of the continent and therefore we find here the continental type of climate which is characterised by extreme temperatures.

The annual rainfall is moderate and is ideal for the growth of grass. ‘Chinook’, a local wind, blow here.

Trees are not there in the prairies. Only trees like willows, alders and poplars grow.

Crops like maize, potatoes, soybeans, cotton and alfa-alfa are grown in the areas where rainfall is over 50 cm.

In the areas with poor rainfall, grasses are short and sparse. In these areas, cattle¬rearing is done. Bison or the American buffalo is the most important animal of this region.

The people of this region are hardworking. The USA and Canada are located in this region.

The prairies are known as the ‘Granaries of the world’ because surplus wheat is produced here.

Dairy farming is also a major industry.

Minerals such as coal and iron are found in abundance. Roads, railways and canals— all are in good condition and play an important role in making this region the most industrialised one in the world.

The velds are the temperate grasslands of South Africa. They are bound by the Drakensberg Mountains on the east. To its west lies the Kalahari desert. On the northeastern part, high velds are located that attain a height of more than 1600 m in some places.

The velds are characterised by a mild climate. They receive rainfall mainly in the summer months from November to February.

The velds do not have much vegetation. Grasses dominate the landscape. The popular varieties of grass are—red grass, acacia and maroola.

The animals found in this region are—lions, leopards, cheetah and kudu.

Cattle rearing and mining are two important activities in the velds. Soils are not very fertile.

The main crops are maize, wheat, barley, oats and potato. Cash crops grown here are tobacco, sugarcane and cotton.

The people of this region are mostly engaged in sheep rearing.

Merino sheep are very popular because its wool is very warm.

Dairy farming is also an important activity Dairy product like butter, cheese is produced for both domestic supply and also for export.

The velds have a rich reserve of minerals. Gold and diamond mining are major occupations of people of this region.

Johannesburg is famous for gold. It is known as the gold capital in the world.

Kimberley is famous for its diamond mines.

Grassland: A region where grasses form the dominant type of plant life.

Prairie: The word prairie has been originated from Latin word priata which means meadow.

Red Indians: native Americans.

Chinook: It is a hot wind that blows in winter and therefore raises the temperature within a short time.

Ranches: They are large cattle farms.

Bison: The American buffalo.

Cowboys: The sturdy men who look after the ranches.

Combine: A single machine which can combine the tasks of sowing, ploughing and threshing, i.e., a three-in-one.

Veld: Velds are the temperate grasslands of South Africa.

Human Environment Interactions Class 7 Notes Geography Chapter 8

 

Human Environment Interactions – The Tropical and the Subtropical Region Class 7 Notes Social Science Geography Chapter 8

Human beings interact with the environment and are dependent on it for a number of things.

Life in the Amazon Basin

  • The Amazon River Basin lies near the equator.
  • Amazon river was discovered by a Spanish explorer, Vicente Yanez Pinzon.
  • The Amazon basin lies in the tropical region close to the equator between 10°N and 10°S, and the river Amazon flows through this region.
  • The Amazon river basin drains portions of Brazil, parts of Peru, Bolivia, Ecuador, Columbia and a small part of Venezuela.

Climate

  • The Amazon basin stretches directly on the equator and is characterized by hot and wet climate throughout the year.
  • There are heavy rainfall and high humidity.

Rainforest

  • As it rains heavily, thick forests grow in this region.
  • The forests are in fact so thick that the dense roof created by leaves and branches do not allow the sunlight to reach the ground.
  • The rainforest is rich in flora and fauna.
  • The basin is home to thousands of species of insects.

People of the Rainforests

  • People grow most of their food in small areas after clearing some trees in the forest.
  • Slash and burn agriculture is prevalent.
  • The development activities are leading to the gradual destruction of the biologically diverse rainforest.

Life in the Ganga-Brahmaputra Basin

  • The tributaries of rivers Ganga and Brahmaputra together form the Ganga- Brahmaputra basin in the Indian subcontinent.
  • The plains of the Ganga and the Brahmaputra, the mountains and foothills of the Himalayas and the Sunderbans delta are the main features of this region.
  • The Ganga and Brahmaputra rivers together form the largest delta in the world.
  • The basin area has varied topography. The mountain areas with steep slopes have inhospitable terrain.
  • Agriculture is the main occupation of the people where flat land is available to grow new crops.
  • Wheat, maize sorghum, gram and millets are the important crops of the region.
  • The vegetation cover of the area varies according to the type of landforms.
  • There is a variety of wildlife in the basin. In the delta areas, Bengal tiger, crocodiles and alligators are found.
  • Fish and rice is the staple diet of the people.
  • The Ganga-Brahmaputra plain has several big towns and cities like Allahabad, Kanpur, Varanasi, Lucknow, Patna and Kolkata.
  • All four means of transport are well-developed in the Ganga-Brahmaputra Basin.
  • Tourism is an important activity in the region.

The Amazon Basin lies in the equatorial region. The river Amazon flows through this region. Numerous tributaries join the Amazon river to form the Amazon Basin.

The river basin drains portions of Brazil, parts, of Peru Bolivia, Equador, Columbia and a small part of Venezuela.

The climate of the Amazon Basin is hot and wet throughout the year. It rains almost every day. During day time temperatures are high but at night the temperature goes down.

Thick forests are found in the Amazon Basin. As sunlight does not reach the ground, only shade tolerant vegetation grows here, for examples, orchids and bromeliads.

The rainforest is rich in fauna. A variety of birds is found here. Apart from animals like monkeys, sloth, etc. various species of reptiles and snakes are also found in these forests.

The Basin is also the home to thousands of species to insects.

The people of the Amazon Basin are mainly engaged in agriculture. They grow tapioca, pineapple and sweet potato. Their staple food is manioc. They also grow cash crops like coffee, maize and cocoa.

The life of the people of the Amazon basin is slowly changing, in 1970 the Trans-Amazon highway made all parts of the rainforest accessible. Aircraft and helicopters are also used for reaching various places.

Due to these developmental activities, a large area of the rainforest has been disappearing annually in the Amazon Basin.

Life in the Ganga-Brahmaputra Basin

  • The tributaries of rivers Ganga and Brahmaputra together from the Ganga-Brahmaputra Basin in the Indian subcontinent.
  • The plains of the Ganga and the Brahmaputra, the mountains and the foothills of the Himalayas and the Sundarbans delta are the main features of this basin.
  • The area of the basin enjoys a monsoon climate. The summers are hot and the winters cool.
  • The basin area has a varied topography. The mountain areas of the basin have thin population. The plain area has thick population.
  • Agriculture is the chief occupation of the people. The main crop is paddy. Some other crops like the wheat, maize, grain, millets etc. and some cash crops like sugarcane and jute are also grown.
  • Tropical deciduous trees grow in the Ganga, Brahmaputra plain. Teak, sal and peepal are also found. The delta is covered with mangrove forests.
  • The basin is rich in wildlife. A variety of fish is found here. Fish and rice is the staple food of the people living in the area.
  • Several big towns and cities such as Allahabad, Kanpur, Varanasi, Lucknow, Patna and Kolkata are there in the Ganga-Brahmaputra plain.
  • All four means of transport are available here.
  • Tourism is also an important activity of the basin. Tourists from different parts of the world come to see the Taj Mahal, Buddhists stupas, Imambara, wildlife sanctuaries etc.

Mouth: The place where a river flows into another body of water is known as the river’s mouth.

Tributaries: These are small rivers that join the main river.

Bromeliads: These are special plants that store water in their leaves.

Slash and Burn Agriculture: It is a type of cultivation in which farmers clear a patch of land by cutting down trees and bushes. These are then burnt which releases the nutrients into the soil. Now the field becomes ready for growing crops.

Manioc: This is the staple food of the people of the Amazon basin.

Maloca: Large apartment like houses with steeply slanting roofs are called malocas.

Population Density: It refers to the number of persons that live in one sq. km. of area.

Terrace Farming: It is a type of farming in which terraces are built on steep slopes to create flat surfaces on which crops are grown. The slope is removed so that water does not run off rapidly.

Piranha: It is a type of fish that eats flesh.

Human Environment Class 7 Notes Geography Chapter 7

 

Human Environment – Settlement Transport and Communication Class 7 Notes Social Science Geography Chapter 7

Human beings are dependent on the environment.

To grow food, build homes and develop better means of transport and communication, human beings have modified the environment.

Settlements

  • Settlements are places where people build their homes.
  • The settlements earlier grew near the river valleys as the water was easily available and the land was fertile.
  • Settlements can be permanent or temporary.
  • Settlements which are occupied for a short time are called temporary settlements.
  • In permanent settlements, people build homes to live in.
  • Settlements can be rural or urban. Rural settlements can be compact or scattered.
  • People in rural areas practice agriculture. In the urban area, people are mostly engaged in services.

Transport

  • Transport is the means by which people and goods move.
  • With the invention of the wheel, transport became easier.
  • Earlier donkeys, mules, bullocks and camels were used for transportation.
  • Earlier traders took the land route or sea route for transportation. Now it takes only 6-8 hours to travel from India to Europe.
  • The four major means of transport are roadways, railways, waterways and airways.

Roadways

  • The most commonly used means of transport, especially for short distances, are roads. They can be metalled or unmetalled.

Railways

  • Railways are the fastest means of land transport and can carry bulky materials over a long distance.
  • The railways carry people over long distances quickly and economically.
  • The invention of the steam engine and the industrial revolution helped in the speedy development of rail transport.
  • Diesel and electric engine have largely replaced the steam engines.
  • Now superfast trains have been introduced to make travelling faster.
  • Indian Railways network is the largest in Asia.

Waterways

  • Waterways are the cheapest means of transportation for carrying heavy and bulky goods over long distances.
  • There are mainly two types of routes, inland waterways and sea routes.
  • Navigable rivers and lakes are used as inland waterways.
  • Sea routes are connected through ports.

Airways

  • Airways are the fastest and most expensive mode of transport.
  • It is the only mode of transport to reach the most remote and distant areas especially where there are no roads and railways.
  • Some major airports in the world are Delhi, Mumbai, New York, London, Paris, Frankfurt and Cairo etc.

Communication

  • Process of conveying the message to others is known as communication.
  • Different modes of communication are used to provide information, to educate as well as to entertain.
  • Communication is of two types namely, personal and mass communication.
  • Through newspaper, radio and television, we can communicate with a large number of people. They are, therefore, called mass media.
  • Satellites, Internet, Wireless telephone are the main modes of communication.

Places, where people build their homes, are called settlements. Early settlements grew near the river valleys because of the easy availability of water and fertile land there.

By and by human settlements became larger with the development of trade, commerce and manufacturing.

Settlements are of two types—permanent and temporary.
People make their temporary settlements in deep forests, hot and cold deserts and mountains and practise hunting, gathering, shifting cultivation, etc. Under permanent settlements, people build homes to live in.

Human settlements may be rural and urban. The villages are rural settlement where people do farming, fishing, forestry, etc.

Rural settlements can be compact or scattered. In a compact settlement, houses are built closely to each other. In a scattered settlement house are spaced over an extensive area.

Houses under rural settlements are built of mud, clay, stones, straw, etc.

Urban settlements are found in towns and cities. People here are engaged in manufacturing, trading and services.

Transport is essential to go from one place to another. In the early days, people travelled long distances on foot. They used animals to carry their goods. Gradually, several means of transport developed, although animals like donkeys, mules, bullocks and camels continued to be used even today.

An aeroplane is the fastest mode of transport. It saves our precious time and energy.

The four means of transport are—roadways, railways, waterways and airways.

Roads can be metalled and unmetalled.

Manali-Leh highway in the Himalayan Mountain is one of the highest roadways in the world.

Roads built underground are called subways/under paths. Flyovers are built over raised structures.

The railways carry people and heavy goods over long distances. The railway network is well developed over the plain areas.

The Indian railway network is well developed and is the largest in Asia.

Waterways are the cheapest means of transport. They are used for carrying heavy and bulky goods over long distances. There are two types of waterways inland waterways and sea routes.

Navigable rivers and lakes are used as inland waterways.

Sea routes and oceanic routes are mostly used for transporting merchandise and goods from one country to another. These routes are connected with the ports.

Some important ports of the world are—Singapore and Mumbai in Asia, New York, Los Angeles in North America, Rio de Janeiro in South America, Durban and Cape Town in Africa, Sydney in Australia, London and Rotterdam in Europe.

Airways are the fastest means of transport. It is the only mode of transport to reach the most remote and distant areas especially where there are no roads and railways.

Helicopters are useful in most inaccessible areas and in the time of calamities for rescuing people and other associated works.

Some important airports are Delhi, Mumbai, New York, London, Paris, Frankfurt and Cairo.

The process by which we convey messages to others is known as communication.

Newspapers, radio and television are important means of communication. They are called mass media because we can communicate with a large number of people at the same time.

The satellites have made communication even faster.

Wireless telephonic communications through cellular phones have become very popular today.

The Internet provides us with worldwide information and interaction.

    

Settlement: It refers to a place where people build their homes. ,

Site: It refers to a place where a building or a settlement develops.

Transhumance: It is a seasonal movement of people.

Compact settlement: It is a closely built area of dwellings.

Scattered settlement: When dwellings are spaced over an extensive area.

Transport: It is the means by which people and goods move from one place to another.

Metalled roads: These are pucca roads and are used in all the weather.

Unmetalled roads: These are Kutcha roads. They are out of work during the rainy season.

Subways: Underground roads are called subways.

Flyovers: These are built over raised structures.

Communication: The process through which we convey messages to others.

Mass Media: Newspapers, radio and television are called mass media because they communicate with a large number of people at the same time.

Natural Vegetation and Wild Life Class 7 Notes Geography Chapter 6

 

Natural Vegetation and Wild Life Class 7 Notes Social Science Geography Chapter 6

Natural vegetation means the plants that grow naturally without human interference.

Natural vegetation can be categorised into three categories namely; forest, grassland and desert.

The change in the type of natural vegetation occurs mainly because of the changes of climatic conditions.

Forests

  • Forests grow where temperature and rainfall are plentiful to support a tree cover.
  • Forests are of six types: Tropical Evergreen, Tropical Deciduous, Temperate Evergreen, Temperate Deciduous, Mediterranean Vegetation, and Coniferous forests.
  • Tropical Evergreen Forests are those which occur in the region near the equator and close to the tropics.
  • Tropical Deciduous Forests are monsoon forests which shed their leaves in the dry season to conserve water.
  • Temperate Evergreen Forests are located in the mid-latitudinal coastal region.
  • Temperate Deciduous Forests are those which shed their leaves in the dry season.
  • Mediterranean Vegetation is found around the Mediterranean Sea in Europe.
  • Coniferous Forests are found in areas along the Taiga.

Grasslands

  • Grasslands are found in the regions of moderate rainfall. They are of two types—Tropical Grasslands, which have tall coarse grass, and Temperate Grasslands.
  • Tropical Grasslands occurs on either side of the equator and extend till the tropics. Tropical Grassland of Africa is called Savannah.
  • Temperate Grasslands are in mid-latitudes and are called prairies, steppes, etc. The grass is usually short here.

Thorny Bushes

  • Thorny bushes are found in the dry desert-like regions.
  • These are found in areas with scanty rain and scorching heat.

Tundra Vegetation

  • Mosses, lichens and very small Shrubs are found in cold regions. This is called tundra type vegetation.
  • It is found in polar areas.

Trees, grass, lichen, mosses, etc. that grow naturally without human interference constitute natural vegetation.

The growth of natural vegetation depends on temperature and moisture. It also depends on factors such as slope and thickness of soil.

Natural vegetation is classified into three categories—forests, grasslands and shrubs.

The changes in the type of natural vegetation occur mainly because of the changes in climatic condition.

Forests grow where temperature and rainfall are plentiful to support a tree cover. Forests may be dense and open.

Tropical evergreen forests also known as tropical rainforests are very dense and are found in the regions near the equator and close to the tropics. Hardwood trees such as rosewood, ebony, mahogany are common here.

Tropical deciduous forests are monsoon forests. They are found in the large part of India, Northern Australia and in Central America. They shed their leaves in dry seasons. Trees like sal, teak, neem and shisham are found here.

Temperate evergreen forests are commonly found along the eastern margin of the continents. In these forests both hard and softwood trees such as oak, pine, eucalyptus, etc. are found.

Temperate deciduous forests are found in the northeastern part of USA, China, New Zealand and Chile. They shed their leaves in the dry season. Trees like oak, ash, beech etc. and animals like deer, foxes, wolves are common in these forests.

Mediterranean vegetation is mostly found in the areas around the Mediterranean sea in Europe, Africa and Asia. Mediterranean vegetation is mainly comprised of citrus fruits such as oranges, figs, olives and grapes.

Coniferous forests are also known as Traga. These forests are found in the higher latitudes of Northern hemisphere. They are also found in the higher altitudes. The trees are tall, softwood evergreen trees. Chir, pine, cedar is an important variety of trees in these forests. Animals such as silver fox, mink, polar bear are common here.

Grasslands include tropical and temperate grasslands. Tropical grasslands grow in the areas of moderate to low amount of rainfall. Savannah grasslands of Africa present a suitable example of these types of grasslands. Animals like elephants, zebras, giraffes, dear are commonly found here.

Temperate grasslands are found in the mid-latitudinal zones and in the interior part of the continents. Short and nutritious grass in found here. Common animals are buffaloes, bison, antelopes etc.

Thorny bushes are found in the dry deserts. Here, vegetation cover is scarce because of poor rain and scorching heat.

Polar regions are cold and their natural vegetation is limited here. Only mosses, lichens and very small shrubs are found here. Vegetation found in the polar regions is called Tundra type of vegetation. Seal, walruses, musk-oxen, Arctic owl etc. are common here.

    

Natural vegetation: Trees, grass, lichens, mosses, etc. that grow naturally without the interference of human beings are called natural vegetation.

Forests: They grow where temperature and rainfall are plentiful to support a tree cover. Forests may be dense and open.

Grasslands: They grow in the region of moderate rain.

Shrubs: These consists of thorny shrubs and scrubs.

Anaconda: It is one of the world’s largest snakes found in the tropical rainforest. Taiga. It means pure or untouched in the Russian language.

Water Class 7 Notes Geography Chapter 5

 

Water Class 7 Notes Social Science Geography Chapter 5

3/4th of earth’s surface is covered by water, so the earth is called the blue planet.

The sun’s heat causes evaporation of water vapour. When the water vapour cools down, it condenses and forms clouds. From there, it may fall on the land or sea in the form of rain, snow or sleet.

The process by which water changes its form and circulates between oceans, atmosphere and land is known as the water cycle.

Our earth is like a terrarium.

The major source of fresh water are the rivers, ponds, springs and glaciers.

The ocean bodies and the seas contain salty water.

Distribution of Water on Earth

  • About three-fourths of the earth’s surface is covered by water.
  • On earth 97% of water is saline and 3% of water is fresh water.
  • The following table gives the distribution of water in percentage:

  • Water is absolutely essential for survival.

Movements

  • Unlike the calm water of ponds and lakes, ocean water keeps moving continuously.
  • The movements which occur in oceans are of three types: waves, tides and currents.

Waves

  • When the water on the surface of the ocean rises and falls alternately, they are called waves.
  • An earthquake, a volcanic eruption or underwater landslides can shift large amounts of ocean water. As a result, huge tidal wave may be formed which is called tsunami.
  • Tsunami in South and South-East Asian coast had caused havoc in December 2004.

Tides

  • The rhythmic rise and fall of ocean water twice in a day is called a tide.
  • Tides are of two types: spring tides and neap tides.

Ocean Currents

  • Ocean currents are streams of water flowing constantly on the ocean surface in different directions.
  • Ocean currents are of two types, warm and cold.
  • The Labrador ocean current is a cold current, while the Gulf Stream is a warm current.

Water is very important for our survival. It continuously changes its form and circulates between oceans and atmosphere.

We get fresh water from the rivers, ponds, springs and glaciers.

The ocean bodies and the seas contain salty water.

Three-fourth of the earth surface is covered by water. But all the water on earth is not available to us. 97.3% of water is saline or salty found in oceans and seas. Only 3% is fresh water. Its 3% is available to us, which we use in our daily life.

Many countries are facing water scarcity due to this fact. What is available is also not fit for drinking because it is polluted badly due to a variety of reasons.

Ponds and lakes have calm water whereas ocean water keeps moving continuously. The movements that occur in oceans can be categorized as waves, tides and currents.

When the water on the surface of the ocean rises and falls alternately, they known as waves.

During stormy weather, huge waves are formed. These waves are very strong and cause heavy destruction.

Tsunami, a huge tidal wave, is very strong. The tsunami of 2004 caused widespread damage in the coastal areas of India.

Tides are the rhythmic rise and fall of ocean water which occur twice in a day. It is high tide when water covers much of the shore by rising to its highest level. It is low tide when waterfalls to its lowest level and recedes from the shore.

During the full moon and new moon days, the sun, the moon and the earth are in the same line and the tides are highest. These tides are called spring tides.

When the moon is in its first and last quarter, the ocean waters get drawn in diagonally opposite directions by the gravitational pull of sun and earth resulting in low tides. These tides are called neap tides.

High tides help in navigation.

Ocean currents are streams of water flowing constantly on the ocean surface in definite directions.

Ocean currents may be warm or cold. The Labrador Ocean current is cold current while the Gulf Stream is a warm current.

The areas where the warm and cold currents meet provide the best fishing grounds of the world.

Evaporation: It is the process through which water turns into vapour.

Condensation: It is the process in which water vapour turns into water droplets.

Water cycle: It is the process by which water continually changes its form and circulates between oceans, atmosphere and land.

Terrarium: It is an artificial enclosure for keeping small house plants.

Precipitation: Falling of moisture in the form of rainfall, snow, sleet and hailstone.

Waves: When the water on the surface of the ocean rises and falls alternately, they are called waves.

Tsunami: Tsunami is a huge tidal wave.

Tide: Tide is the rhythmic rise and fall of ocean water that occurs twice in a day.

Springtide: During the full moon and new moon days, the sun, the moon and the earth are in the same line and the tides are highest. These tides are called spring tides.

Neap tide: When the moon is in its first and last quarter, the ocean waters get drawn in diagonally opposite directions by the gravitational pull of sun and earth resulting in low tides. These tides are called neap tides.

Ocean currents: These are streams of water flowing constantly on the ocean surface in definite directions.

Air Class 7 Notes Geography Chapter 4

 

Air Class 7 Notes Social Science Geography Chapter 4

Our atmosphere is surrounded by a huge blanket of air called atmosphere.

Composition of the Atmosphere

  • Nitrogen and oxygen are the two gases which make up the bulk of the atmosphere.
  • Carbon dioxide, helium, ozone, argon and hydrogen are found in lesser quantities.
  • Apart from these gases, tiny dust particles are also present in the air.

Structure of the Atmosphere

  • Our atmosphere is divided into five layers starting from the earth’s surface.
  • The first layer is the Troposphere whose average height is 13 km. The troposphere is the layer in which the air we breathe exist. Almost all weather phenomena occur here.
  • The second layer is the Stratosphere which extends up to 50 km.
  • The third layer is the Mesosphere which extends up to the height of 80 km.
  • The fourth layer is the Thermosphere which extends from 80 km to 400 km.
  • The uppermost layer of the atmosphere is Exosphere which has very thin air.

Weather and Climate

  • Weather is the Hour-to-hour, day-to-day condition of the atmosphere.
  • Climate is the weather conditions for a large period and of a large area.

Temperature

  • The degree of hotness and coldness of the air is called temperature.
  • The temperature of the atmosphere changes not only between day and night but also from season to season, an important factor that influences the distribution of temperature is insolation.
  • Insolation is the incoming solar energy intercepted by the earth.
  • The amount of insolation decreases from the equator towards the poles.
  • Temperature is measured in Celsius and Fahrenheit.

Air Pressure

  • Air pressure is defined as the pressure exerted by the weight of air on the earth’s surface.
  • Horizontally the distribution of air pressure is influenced by the temperature of the air at a given place.
  • In areas having a lower temperature, the air is cold.
  • The air always moves from high-pressure areas to low-pressure areas.

Wind

  • The movement of air from high-pressure areas to the low-pressure area is called Wind.
  • Winds can be broadly divided into three types: permanent winds, seasonal winds and local winds.
  • On 25 October 1999, cyclonic winds originated as depression and affected Odisha killing thousands of people.

Moisture

  • When water evaporates from land and other water bodies, it becomes water vapour.
  • Moisture in the air at any time is known as humidity.
  • When the water vapour rises, it starts cooling. The water vapour condenses causing the formation of droplets of water.
  • When these droplets of water become too heavy to float in the air, they come down as precipitation.
  • Precipitation is the falling of moisture in the form of rainfall, snow, fog, sleet and hailstones.
  • On the basis of mechanism, there are three types of rainfall: the convectional rainfall, the orographic rainfall and the cyclonic rainfall.
  • Rainfall is very important for the survival of plants and animals.

The atmosphere is a thin blanket of air that surrounds the earth. It protects us from the harmful rays of the sun. It consists of the main nitrogen (78%) and oxygen (21%). Carbon dioxide, helium, ozone, argon and hydrogen are found in lesser quantities.

Nitrogen is very important for plants. Their survival depends on this gas.

Oxygen is essential for humans and animals. They breathe in oxygen, produced by green plants during photosynthesis.

Green plants take in carbon dioxide which is released by humans and animals. Thus, there is a mutual relation between the plants and the humans or animals. Hence, we should protect plants and trees for our own benefit.

The atmosphere is divided into five layers starting from the earth’s surface. These layers are—Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere.

The troposphere is the layer in which the air we breathe exists. Almost all weather phenomena occur here.

The stratosphere contains a layer of ozone gas.

The mesosphere extends up to the height of 80 km. Meteorites burn up in this layer on entering from the space.

Thermosphere helps in radio transmission.

Exosphere is the uppermost layer, where the air is very thin.

Weather is hour-to-hour, day-to-day condition of the atmosphere.

Climate is the average weather condition of a place for a longer period of time.

The temperature of the atmosphere remains changing. The degree of hotness and coldness of the air is known as temperature.

Insolation is an important factor that influences the distribution of temperature. The amount of insolation decreases from the equator towards the poles. Therefore, the temperature decreases in the same way.

Air above us presses us from all directions with a great force on our body and our body exerts a counter pressure.

Air pressure is the pressure exerted by the weight of air on the earth’s surface. As we go up the layers of the atmosphere, the pressure falls rapidly.

Low pressure is associated with cloudy skies and wet weather. High pressure is associated with clear and sunny skies. The air always moves from high-pressure areas to a low-pressure area.

Wind is the movement of air from the high-pressure area to low pressure areas. Wind may be gentle. At times it may be strong and devastating.

Winds are of three types—Permanent winds, Seasonal winds and Local winds.

Moisture means humidity. A humid day is one when the air is the fall of water vapour. On a humid day, clothes take longer to dry and sweat from our body does not evaporate easily.

Clouds are masses of water droplets. When these droplets of water become very heavy they come down as precipitation. Precipitation that comes down to the earth in liquid form is called rain.

There are three types of rain on the basis of mechanism—the conventional rainfall, the orographic rainfall and the cyclonic rainfall.

Constituents of air
    

Structure of the atmosphere
    

Atmosphere: Atmosphere is a thin blanket of air that surrounds the earth.

Global warming: When the temperature of the earth’s atmosphere increases due to the increases in carbon dioxide, it is known as global warming.

Weather: The hour-to-hour, day-to-day condition of the atmosphere is known as weather.

Climate: The average weather condition of a place for a longer period of time is known as the climate of a place.

Temperature: The degree of hotness and coldness of the air is known as temperature.

Isolation: Isolation is the incoming solar energy intercepted by the earth.

Air pressure: The pressure exerted by the weight of air on the earth’s surface is known as air pressure.

Wind: Wind is the movement of air from the high-pressure area to low pressure areas.

Moisture: Water vapour present in the atmosphere is known as moisture.

Humidity: Moisture in the air is known as humidity.

Cloud: It is a mass of water droplets.

Precipitation: Falling of water on the earth in the form of rainfall is known as precipitation.

Thermometer: It is an instrument that measures temperature.

Barometer: It measures atmospheric pressure.

Rain gauge: It measures the amount of rainfall.

Wind vane: It shows the direction of the wind.

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