Introduction
👉 The surface of the earth is a complex zone in which three main components of the environment meet, overlap, and interact.
👉 The solid portion of the earth on which we live is called the Lithosphere.
👉 The gaseous layer that surrounds the earth, is the Atmosphere.
👉 Water covers a very big area of the earth’s surface and this area is called the Hydrosphere.
👉The Biosphere is the narrow zone where we find land, water, and air together, which contains all forms of life.
LITHOSPHERE:
👉 The solid portion of the earth is called the Lithosphere.
👉 It 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 divisions of the earth’s surface.
👉The large landmasses are known as the continents and the huge water bodies are called the ocean basins.
All the oceans of the world are connected with one another that’s why the level of seawater remains the same everywhere.
The elevation of the land is measured from the level of the sea, which is taken as zero.
The highest mountain peak Mt. Everest is 8,848 metres above sea level.
The greatest depth of 11,022 metres is recorded at Mariana Trench in the Pacific Ocean.
CONTINENTS:
👉 There are seven major continents.
👉These continents are – Asia, Europe, Africa, North America, South America, Australia, and Antarctica.
👉 The greater part of the landmass lies in the Northern Hemisphere.
Asia:
👉Asia is the largest continent.
👉 It covers about one-third of the total land area of the earth.
👉 The continent lies in the Eastern Hemisphere.
👉 Asia is separated from Europe by the Ural mountains on the west.
👉 The combined landmass of Europe and Asia is called Eurasia.
Africa:
👉Africa is the second-largest continent after Asia.
👉The Equator or 0° latitude runs almost through the middle of the continent.
👉A large part of Africa lies in the Northern Hemisphere.
👉It is the only continent through which the Tropic of Cancer, the Equator, and the Tropic of Capricorn pass.
👉The Sahara Desert, the world’s largest hot desert, is located in Africa.
👉The world’s longest river the Nile flows through Africa.
👉The continent is bound on all sides by oceans and seas.
North America:
👉North America is the third largest continent in the world.
👉 The continent lies completely in the Northern and Western Hemisphere.
👉It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, and to the west and south by the Pacific Ocean.
👉It is linked to South America by a very narrow strip of land called the Isthmus of Panama.
South America:
👉South America lies mostly in the Southern Hemisphere.
👉 The Andes, the world’s longest mountain range, runs through its length from north to south.
👉 South America has the world’s largest river, the Amazon.
👉On the east by the Atlantic Ocean and the west by the Pacific Ocean surrounds it.
Antarctica:
👉Antarctica, completely in the Southern Hemisphere, is a huge continent.
👉 The South Pole lies almost at the centre of this continent.
👉 As it is located in the South Polar Region, it is permanently covered with thick ice sheets.
👉 There are no permanent human settlements.
👉 Many countries have research stations in Antarctica.
👉 India also has research stations there. These are named Maitri and Dakshin Gangotri.
Europe:
👉This continent lies entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere.
👉 The Arctic Circle passes through it.
👉It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east.
Oceania[Australia]:
👉Australia is the smallest continent that lies entirely in the Southern Hemisphere.
👉 It is surrounded on all sides by the oceans and seas.
👉 It is called an island continent.
HYDROSPHERE:
👉More than 71 per cent of the earth is covered with water that’s why the earth is called the blue planet.
👉 The hydrosphere consists of water in all its forms.
👉 As running water in oceans and rivers and in lakes, ice in glaciers, underground water and the water vapour in the atmosphere, all comprise the hydrosphere.
👉 More than 97% of the Earth’s water is found in the oceans and is too salty for human use.
Oceans:
👉All the oceans are interconnected.
👉The ocean waters are always moving.
👉The three chief movements of ocean waters are the waves, the tides, and the ocean currents.
👉 The five major oceans are The Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean, and the Arctic Ocean, in order of their size.
The Pacific Ocean:
👉The Pacific Ocean is the largest ocean.
👉 It is spread over one-third of the earth.
👉 It is almost circular in shape.
👉 Asia, Australia, North and South America surrounded it.
The Atlantic Ocean:
👉It is the second-largest ocean in the world.
👉 It is ‘S-shaped.
👉 The coastline of the Atlantic Ocean is highly indented.
👉 This irregular and indented coastline provide the ideal location for natural harbors and ports.
👉 From the point of view of commerce, it is the busiest Ocean.
👉 It is flanked by North and South America on the western side and Europe and Africa on the eastern side.
The Indian Ocean:
👉The Indian Ocean is the only ocean named after a country, that is, India.
👉The shape of the ocean is almost triangular.
👉 In the north, it is bound by Asia, in the west by Africa, and in the east by Australia.
The Southern Ocean:
👉The Southern Ocean encircles the continent of Antarctica and extend northward to 60 degrees south latitude.
The Arctic Ocean:
👉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 the Bering Strait.
👉 It is bound by the northern coasts of North America and Eurasia.
ATMOSPHERE:
👉The earth is surrounded by a layer of gas called the atmosphere.
👉 It provides us with the air we breathe and protects us from the harmful effects of the sun’s rays.
👉 The atmosphere extends up to a height of about 1,600 kilometers.
👉 The atmosphere is divided into five layers.
👉 These layers starting from the earth’s surface are called the troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere.
👉 The atmosphere is composed of nitrogen 78 per cent, oxygen 21 per cent and other gases like carbon dioxide, argon and others comprise 1 per cent by volume.
👉 Oxygen is the breath of life and nitrogen helps in the growth of living organisms while carbon dioxide is important as it absorbs heat radiated by the earth, thereby keeping the planet warm.
👉 The density of the atmosphere is maximum at the sea level and decreases rapidly as we go up.
👉 The atmosphere exerts pressure on the earth.
👉 Air moves from high pressure to low pressure.
👉 Moving air is known as wind.
BIOSPHERE – THE DOMAIN OF LIFE:
👉The biosphere is the narrow zone of contact between the land, water, and air.
👉 All living organisms including humans are linked to each other and to the biosphere for survival.
👉 The organisms in the biosphere may broadly be divided into the plant kingdom and the animal kingdom.
👉 Increase in the amount of CO2 leads to an increase in global temperatures. This is termed as global warming.
👉A need to limit the use of resources of the earth to maintain the balance of nature between the domains of the lithosphere, the atmosphere, and the hydrosphere.
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