Desert: It is an arid region characterized by extremely high or low temperatures and has scare vegetation. Depending on the temperatures, there can be hot deserts or cold deserts.
The Hot Desert – Sahara:
- It has an area of around 8.54 million sq. km
- The Sahara desert touches eleven countries. These are Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Sudan, Tunisia and W. Sahara.
- It is scorching hot and parch dry.
- It has a short rainy season.
- The temperatures during the day may soar as high as 50o C and the nights may be freezing cold with temperature nearing zero degrees.
Flora and Fauna:
- Vegetation in the Sahara desert includes cactus, date palms and acacia.
- Camels, hyenas, jackals, foxes, scorpions, many varieties of snakes and lizards are the prominent animal species living here.
- Bedouins and Tuaregs are the nomadic tribes rearing livestock such as goats, sheep, camels and horses.
- The Oasis in the Sahara and the Nile valley in Egypt supports settled population.
- Crops such as rice, wheat, barley and beans are also grown.
- Egyptian cotton, famous worldwide is grown in Egypt.
- The discovery of oil in Algeria, Libya and Egypt is constantly transforming the Sahara desert.
- Other minerals found here are iron, phosphorous, manganese and uranium.
The cold desert – Ladakh:
- Ladakh is a cold desert lying in the Great Himalayas on the eastern side of Jammu and Kashmir.
- The Karakoram range in the north and the Zaskar mountains in the south enclose it.
- Indus is the most important river which flows through Ladakh.
- The dry temperatures in summer are just above zero degree and the night temperatures well below -30O
- It is freezing cold in the winters when the temperatures may remain below -40O C for most of the time.
- Ladakh is also known as Khapa-chan which means snow land.
Flora and Fauna:
- Due to high aridity, the vegetation is sparse.
- Groves of willows and poplars are seen in the valleys.
- During the summers, fruit trees such as apples, apricots and walnuts bloom.
- Several species of birds are sighted in Ladakh. Robins, redstarts, Tibetan snowcock, raven and hoopoe are common.
- The animals of ladakh are wild goats, wild sheep, yak and special kinds of dogs.
- The Chiru or the Tibetan antelope is an endangered species. It is hunted for its wool known as Shahtoosh, which is light in weight and extremely warm.
- The people here are either Muslims or Buddhists.
- Some famous monasteries are Hemis, Thiskey, Shey and Lamayuru.
- In the summer season, the people are busy cultivating barley, potatoes, peas, beans and turnip.
- The national highway 1A connects Leh to Kashmir valley through the Zoji la pass.
- Manali – Leh highway crosses four passes, Rohtang la, Baralacha la, Lungalacha la and Tanglang la. The highway opens only between July and September when snow is cleared from roads.
Life in the Amazon basin:
- The tropical region lies very close to the equator; between 10o N and 10o So, it is referred to as the equatorial region.
- The place where a river flows into another body of water is called the river’s mouth.
- The Amazon river basin drains portions of Brazil, parts of Peru, Bolivia, Ecuador, Columbia and a small part of Venezuela.
# Tributaries: These are small rivers that join the main river. The main river along with all its tributaries that drain an area forms a river basin or the catchment area. The Amazon basin is the largest river basin in the world.
- Is characterized by hot and wet climate throughout the year.
- Both days and nights are almost equally hot and humid.
- As it rains heavily in this region, thick forests grow.
- This region is very rich in fauna. Birds such as toucans, humming birds, birds of paradise and bills are common here. Animals like monkeys, sloth and ant-eating tapirs are found here.
- Reptiles like Anaconda, boa constrictor are some of the species.
People of the rain forests:
- People grow most of their food in small areas after clearing some trees in the forest.
- While men hunt and fish along the rivers, women take care of the crops. They grow mainly tapioca, pineapple and sweet potato.
- They practice slash and burn agriculture. It is a way of cultivating land where farmers clear a piece of land by slashing or cutting down trees and bushes. These are then burnt, which releases the nutrients into the soil.
- The staple food of these people is manioc, also known as cassava that grows under the ground like the potato.
- Cash crops like coffee, maize and cocoa are also grown.
- In 1970, the Trans Amazon highway made all parts of the rainforest accessible.
Life in the Ganga – Brahmaputra Basin:
- The basin lies in the sub-tropical region that is situated between 10o N to 30o N latitudes.
- The tributaries of the River Ganga like the Ghaghra, the Son, the Chambal, the Gandak, the Kosi and the tributaries of Brahmaputra drain it.
- The plains of the Ganga and the Brahmaputra, the mountains and the foothills of the Himalayas and the Sunderbans delta are the main features of this basin.
- The area is dominated by monsoon climate.
- The environment plays a dominant role in the distribution of the population.
- The density of the population in the plains is very high.
# Population Density: It is the number of persons that live in one sq.km of area.
- The main crop is paddy.
- Wheat, maize, sorghum, gram and millets are the other crops that are grown.
- Cash crops like sugarcane and jute are also grown.
- In West Bengal and Assam, tea is grown in plantations.
- Silk is produced through the cultivation of silk worms in parts of Bihar and Assam.
- There is a variety of wildlife in the basin. Elephants, deers, tigers and monkeys are common.
- The one-horned rhinoceros is found in the Brahmaputra plain.
- In the delta area, Bengal tiger, crocodiles and alligator are found.
- In the fresh waters of River Ganga, and River Brahmaputra, a variety of dolphin locally called Susu (also called blind dolphin) is found.
- Kolkata is an important port on the River Hooghly.
- Tourism is another important activity of the basin.
Site : The place where a building or a settlement develops is called a site. The natural conditions for selection of an ideal site are –
- Favorable climate
- Availability of water
- Suitable land
- Fertile land
Settlements: are places where people build their homes. They can be permanent or temporary.
Temporary Settlements: Settlements which are occupied for a short time are called temporary settlements. People in these settlements practice hunting, gathering, shifting cultivation and transhumance.
Transhumance: It is a seasonal movement of people. People who rear animals move in search of new pastures according to changes in seasons.
Settlements can be rural or urban.
- The villages are rural settlements where people are engaged in activities like agriculture, fishing, forestry, crafts work and trading etc..
- They can be compact or scattered.
- The towns are small and the cities are larger urban settlements.
- In urban areas the people are engaged in manufacturing, trading and services.
Transport: Transport is the means by which people and goods move. The four major means of transport are roadways, railways, waterways and airways.
- They can be metalled (pucca) and unmetalled (kutcha)
- Manali – Leh highway in the Himalayan Mountains is one of the highest roadways in the world.
- Roads built underground are called subways/under paths.
- Indian railway network is the largest in Asia.
- The Trans-Siberian Railway is the longest railway system connecting St.Petersburg in Western Russia to Vladivostok in the Pacific coast
- Waterways are the cheapest for carrying heavy and bulky goods over long distances.
- They are mainly of two types – inland waterways and sea routes.
- Some of the important inland waterways are the Ganga-Brahmaputra river system, the Great lakes in the N.America and the river Nile in Africa.
- Some of the important ports of the world are Singapore and Mumbai in Asia, New York, Los Angeles in N.America, Rio de Janerio in S.America, Durban and Cape Town in Africa, Sydney in Australia, London and Rotterdam in Europe.
- The fastest way of transport developed.
- It is the only mode of transport to reach the most remote and distant areas where there are no roads and railways.
- Some of the important airports are Delhi, Mumbai, New York, London, Paris, Frankfurt and Cairo
- Is the process of conveying message to others.
- Through newspaper, radio and television we can communicate with a large number of people. They are therefore called mass media.
- Satellites have helped in oil exploration, survey of forest, underground water, mineral wealth, weather forecast and disaster warning.
Natural vegetation is generally classified into three broad categories as follows:
- Forests: which grow where temperature and rainfall are plentiful to support a tree cover. Depending upon these factors, dense and open forests are grown.
- Grasslands: which grow in the region of moderate rain.
- Shrubs: Thorny shrubs and scrubs grown in the dry region.
The changes in the type of natural vegetation occur mainly because of the changes in the climatic condition.
Tropical Evergreen Forests:
- Also called as tropical rain forests.
- Occur in the regions near to equator and close to the tropics.
- Hardwood trees like rosewood, ebony, mahogany are common here.
Tropical deciduous forests:
- Are the monsoon forests found in large part of India, N. Australia and in Central America.
- The hardwood trees found in these forests are sal, teak, neem and shisham.
- Tigers, lions, elephants, langoors and monkeys are the common animals of these regions.
Temperate Evergreen forests:
- These are located in the mid-latitudinal coastal region. They are commonly found along the eastern margin of the continents, e.g., In South east USA, S.China and in SE Brazil.
- They comprise both hard and soft wood trees like oak, pine, eucalyptus, etc.
Temperate Deciduous Forests:
- These are found in the NE part of USA, China, New Zealand, Chile and also found in the coastal regions of W.Europe.
- The common trees are oak, ash, beech etc.
- Deer, foxes, wolves are the commonly found animals. Birds like pheasants, monals are also found here.
- The west and south west margins of the continents have this vegetation.
- Mostly found in the areas around the Mediterranean sea in Europe, Africa and Asia, hence the name.
- These regions are marked for hot dry summers and mild rainy winters.
- Citrus fruits such as oranges, figs, olives and grapes are commonly cultivated.
- These regions are known as ‘Orchards of the world’ for their fruit cultivation.
- These forests are seen in the higher latitudes.
- These are also called as Taiga.
- The trees are tall, softwood evergreen trees. The woods of these trees are very useful for making pulp, which is used for manufacturing paper and newsprint.
- Match boxes and packing boxes are also made from softwood.
- Chir, pine, cedar are the important variety of trees in these forests.
- Silver fox, mink, polar bear are the common animals found here.
- These occur on either side of the equator and extend till the tropics.
- This vegetation grows in the areas of moderate to low amount of rainfall. Ex: Savanna grasslands of Africa
- Elephants, Zebras, giraffes, deer, leopards are common here.
- Tropical Grasslands in East Africa are called Savannahs.
- They are called Campos in Brazil
- They are called Llanos in Venezuela
- These are found in the mid-latitudinal zones in the interior part of the continents.
- Wild buffaloes, bisons, antelopes are common here.
- The temperate grasslands of Argentina are called Pampas.
- They are called Prairie in N.America
- They are called Veld in S.Africa
- They are called Steppe in C.Asia
- They are called Down in Australia.
- The vegetation cover is scarce because of scanty rain and scorching heat.
- This is extremely cold.
- The growth of vegetation is very limited here.
- Only mosses, lichens and very small shrubs are found here. It grows only during the very short summer.
- This is found in the polar areas of Europe, Asia and N.America.
- Seal, walruses, musk-oxen, Arctic owl, Polar bear and snow foxes are some of the animals found here.
- Environment is derived from the French word “Environer/Environner” meaning “neighborhood”
- Environment is the basic life support system. It provides the air we breath, the water we drink, the food we eat and the land where we live.
- The place, people, things and the nature that surround any living organism is called environment. It is a combination of natural and human made phenomena.
- Components of environment: Natural, Human made and Human.
- Natural environment refers to both biotic and abiotic conditions. Biotic is the world of living organisms whereas abiotic is the world of non-living elements.
- The solid crust or the hard top layer of the earth.
- Made up of rocks and minerals and covered by a thin layer of soil.
- Thin layer of air that surrounds the earth.
Ecosystem: it is a system formed by the interaction of all living organisms with each other and with physical and chemical factors of environment in which they live, all linked by transfer of energy and material.
# World Environment day – 5th June.
- Weather is about day to day changes in the atmosphere. It includes changes in temperature, rainfall and sunshine.
Broadly, the major seasons recognized in India are:
- Cold Weather Season (Winter) December to February
- Hot Weather Season (Summer) March to May
- South West Monsoon Season (Rainy) June to September
- Season of Retreating Monsoon (Autumn) October and November.
# Hot and dry winds called Loo blow during the day in the Hot Weather Season.
South West Monsoon Season:
- This season is marked by the onset and advance of monsoon.
- The winds blow from the Bay of Bengal and Arabian Sea towards the land. They carry moisture with them.
- When these winds strike the mountain barriers, rainfall occurs.
Season of Retreating Monsoons or Autumn:
- Winds move backward from the mainland to the Bay of Bengal.
- The southern parts of India, particularly Tamil Nadu and Andhra Pradesh receive rainfall in this season.
Climate: Climate is about the average weather condition, which have been measured over many years.
- The climate of India has broadly been described as Monsoon type.
- Due to India’s location in the tropical region, most of the rain is brought by monsoon winds.
INDIA : CLIMATE, VEGETATION AND WILDLIFE
- The climate of a place is affected by its location, altitude, distance from the sea, and relief.
- Due to varied climatic conditions, India has a wide range of natural vegetation.
Vegetation of India can be divided into five types. They are:
- Tropical Evergreen Forests or Tropical Rain Forest: They occur in the areas which receive heavy rainfall. Important trees found in these forests are Mahagony, ebony and rosewood.
- Tropical Deciduous Forests or Monsoon Forests: Important trees of these forests are sal, teak, peepal, neem and shisham.
- Thorny bushes: Plants are like Cactus, Khair, Babool and Keekar.
- Mountain Vegetation: The trees are coniferous having broad bases and conical tops. Important species of trees are the pine, chir and deodar.
- Mangrove forests: These are grown in the saline water. Example: Sunderbans.
- Gir forest in Gujarat is the home of Asiatic lions.
- Forests of Assam are the home of the elephants and one-horned rhinoceroses.
- Camels and wild asses are found in the Great Indian desert and the Rann of Kuchch respectively.
- India is bounded by the Himalayas in the North, the Arabian Sea in the west, the Bay of Bengal in the East and the Indian Ocean in the south.
- Peninsula : Peninsula is a piece of land which is surrounded by water on three sides of it.
- Area of India – 3.28 million square kilometers
- The North South extent of India is 3,200 kms
- The East West extent of India is 2,900 kms
- The Tropic of cancer (23 1/20N) passes through the middle of India.
- From north to south, the mainland extends between 804’ N and 3706’N latitudes.
- From west to east, the mainland extends between 6807’ E and 97025’E longitudes.
- The longitude 82030’E is called the Indian Standard Time or the Standard Meridian of India.
- Seven countries share boundary with India : China, Nepal, Bhutan, Myanmar, Afghanistan, Pakistan, Bangladesh.
- Tributary: A river or stream which contributes its water to a main river by discharging it into main river from either side.
India is marked by a diversity of physical features such as mountains, plateaus, plains, coasts and islands.
- The northern most of Himalayas are the Greater Himalayas or Himadri. Some of the world’s highest peaks are in this range.
- The middle Himalayas or the Himachal has some of the beautiful hill stations.
- The southern part of the Himalayas are the Lesser Himalayas or the Shiwaliks.
- These lie to the south of the Himalayas.
- These are formed by the alluvial deposits laid down by the rivers – the Indus, the Ganga and the Brahmaputra and their tributaries.
Great Indian Desert:
- In the western part of India lies the Great Indian desert.
- It is a dry, hot and sandy stretch of land.
- To the south of northern plains lies the Peninsular plateau. It is triangular in shape.
- Aravali hills, one of the oldest ranges of the world, border it on the north-west side.
- The Vindhyas and the Satpuras are the important ranges.
- The rivers Narmada and Tapi flow through these ranges. These are the west flowing rivers.
- The Western Ghats and the Eastern Ghats border the plateau.
- The Western Ghats are almost continuous and the Eastern Ghats are broken and uneven.
- To the west of the Western Ghats and the East of the Eastern Ghats lie the Coastal plains.
- Two groups of islands also form part of India.
- Lakshadweep Islands are located in the Arabian Sea.
- The Andaman and the Nicobar islands lie to the southeast of the Indian mainland in the Bay of Bengal.
- The solid portion of the earth on which we live is called the Lithosphere. The word Litho is originated from the Greek language, Lithos meaning stone.
- The gaseous layers that surround the earth, is the Atmosphere. The word Atmos is originated from the Greek language, meaning Vapor.
- The area covered by water is called the Hydrosphere, and it comprises water in all its forms. The word Hudor is originated from the Greek language, meaning Water.
- The Biosphere is the narrow zone where the land, water and air are found together and it contains all forms of life. The word Bios is originated from the Greek language, meaning Life.
- The lithosphere comprises the rocks of the earth’s crust and the thin layers of soil that contain nutrient elements which sustain organisms.
- There are two main division of the earth’s surface. The large landmasses are known as the continents and the huge water bodies are called the ocean basins.
- The highest mountain peak Mt. Everest is 8,848 metres above the sea level. The greatest depth of 11,022 meters is recorded at Mariana Trench in the Pacific Ocean.
- There are 7 major continents. They are Asia, Europe, Africa, North America, South America, Australia and Antarctica. The greater part of the land mass lies in the Northern Hemisphere.
- Asia is the largest continent. It covers about 1/3rd of the total land area of the earth. It is in the Eastern Hemisphere. The Tropic of Cancer passes through the Continent. Asia is separated from the Europe by the Ural mountains on the west.
- Europe lies to the west of Asia. The Arctic circle passes through it. It is bound by water bodies on 3 sides.
- Africa is the second largest continent after Asia. The Equator or 0o latitude runs almost through the middle of the continent. A large part of it lies in the N. Hemisphere. It is the only continent through which the Tropic of Cancer, the Equator and the Tropic of Capricorn The Sahara desert, the world’s largest hot desert, is located in Africa. It is bound on all sides by oceans and seas.
- North America is the third largest continent of the world. It is linked to South America by a very narrow strip of land called the Isthmus of Panama. The continent completely lies in the Northern and Western Hemisphere. Three oceans surround this continent.
# Isthmus – A narrow strip of land joining two landmasses.
# Strait – A strait is a narrow passage of water connecting two large water bodies like seas and oceans.
- South America lies mostly in Southern Hemisphere. The Andes, world’s longest mountain range runs through its length from north to south. It has the world’s largest river, the Amazon.
- Australia is the smallest continent that lies entirely in the Southern Hemisphere. It is an island continent.
- Antarctica, completely in the Southern Hemisphere, is a huge continent. The South pole lies almost at the centre of this continent. The research stations of India in Antarctica are Maitri and Dakshin Gangotri.
Oceans: Oceans are the major part of hydrosphere.
- The oceans are always moving. The three chief movements of ocean waters are the waves, the tides and the ocean currents.
- The four major oceans are the Pacific Ocean, the Atlantic Ocean, the Indian Ocean and the Arctic Ocean, in order of their size.
- The Pacific ocean is spread over one-third of the earth. Asia, Australia, North and South Americas surround it.
- The Atlantic ocean is ‘S’ shaped. It is flanked by the North and South Americas on the western side, and Europe and Africa on the eastern side. The coastline of Atlantic ocean is highly intended. This irregular and indented coastline provides ideal location for natural harbors and ports. From the point of view of commerce, it is the busiest ocean.
- The Indian ocean is almost triangular in shape. In the North, it is bound by Asia, in the west by Africa and in the east by Australia.
- The Arctic ocean is located within the Arctic Circle and surrounds the North Pole. It is connected with the Pacific Ocean by a narrow stretch of shallow water known as Bering Strait. It is bound by northern coasts of North America and Eurasia.
- The atmosphere extends up to a height of about 1,600 kms. The atmosphere is divided into five layers based on composition, temperature and other properties.
- These layers starting from earth’s surface are called the troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere.
- The density of the atmosphere varies with height. It is maximum at the sea level and decreases rapidly as we go up. The temperature also decreases as we go upwards. The pressure also varies from place to place.
- Moving air is known as wind.
Biosphere – the Domain of Life:
- The organisms in the biosphere may broadly be divided into the plant kingdom and the animal kingdom. The three domains of the earth interact with each other and affect each other in some way or the other.