Introduction

NCERT is a basic study material in the preparation of UPSC. One must read all the topics thoroughly according to the syllabus. The following article gives us information about the Major Domains of the Earth.

Life on earth is possible because of the components such as land, water and air. The land portion of the earth where organisms live together is known as the Lithosphere. It consists of rocks found in the earth’s crust and different types of soils.

The water part of the earth is known as Hydrosphere. Most of the part of the earth is covered with water. It is present in a huge amount. The air in the earth constitutes the Atmosphere.

In the Atmosphere, different types of gases are present like oxygen, nitrogen, hydrogen, carbon dioxide, argon, etc. And a zone where all the three i.e. land, air and water are present is called Biosphere.

Geography NCERT Notes For UPSC IAS Preparation

Lithosphere

  • It is the hard layer present on the top layer or on the crust of the earth.
  • This is the portion of the earth where human beings live.
  • The lithosphere consists of different types of minerals, rocks and soils.
  • The whole lithosphere is an uneven surface containing different landforms like mountains, plateaus, plains, valleys, etc.
  • Earth’s surface can be divided into two main components – Continents and huge water bodies.
  • The highest mountain peak in the world is Mount Everest at a height of 8,848 m above sea level.
  • The deepest location on the earth is the Mariana trench in the Pacific Ocean and is about 11,034 meters deep.

Geography NCERT Notes For UPSC IAS Preparation

Hydrosphere

About 70% of Earth’s portion is covered with water that’s why it is called the blue planet. All types of water bodies come under hydrosphere. It includes running water like rivers, oceans, lakes, glaciers which can be in ice form, underground waters, and water vapour content in the Atmosphere.

Most of the water found on the earth or say in the oceans are salty which cannot be used for human beings. Also, glaciers and ice sheets also contain water but in another form. A very small percentage of water is available which can be used by human beings. Hence, there is a scarcity of water.

Oceans

  • This is a part of the hydrosphere.
  • Ocean water is not constant always. There are different types of movements in it.
  • Movement types are- Waves, tides and ocean currents.
  • Four major oceans found on earth are- The Pacific Ocean, the Atlantic Ocean, The Indian Ocean, and The Arctic Ocean.
  • The largest ocean of all four is the Pacific Ocean. The deepest location of earth, Mariana Trench lies in it. It is surrounded by Asia, Australia, North and South America.
  • The second-largest ocean name is given to The Atlantic Ocean. As the Pacific Ocean is almost circular, The Atlantic Ocean is ‘S’ shaped. Its coastline is irregular therefore considered ideal places for ports and natural harbours.
  • The Indian Ocean is an Ocean named after a country. It is almost triangular in shape.
  • The Arctic Ocean lies in the Arctic Circle and covers the North Pole.

Geography NCERT Notes For UPSC IAS Preparation

Atmosphere

  • A layer of gas surrounding the earth is called the Atmosphere. It is like a thin blanket.
  • It protects us from harmful radiations coming from the sun and also provides us with a life-sustaining unit, air.
  • Its height extension from the earth’s surface is about 1,600 kilometres.
  • It can be divided into five layers – the troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere.
  • Nitrogen and oxygen are the main components of the Atmosphere.
  • Nitrogen makes up to 78% of the air and oxygen up to 21%
  • Other gases present in the Atmosphere like carbon dioxide, argon, etc. constitute only 1%.
  • Oxygen is used for breathing and nitrogen is used in different forms in the Atmosphere like nitrogen fixation.
  • Carbon dioxide keeps the planet warm by trapping some of the sun’s radiations in the Atmosphere. Carbon dioxide and nitrogen both help in the growth of plants.
  • The density of the Atmosphere varies differently at different heights like it is maximum at the sea level whereas in the mountains it decreases as we go up. That’s why while climbing mountains we experience breathing problems as the density decreases there.
  • The mountain climbers carry oxygen cylinders to overcome this problem.
  • There is some pressure exerted by the Atmosphere. And also as we go upwards temperature will also decrease.

Geography NCERT Notes For UPSC IAS Preparation

Biosphere

It’s a zone where all the three, land, air and water meet and interact. Life exists in this zone. Many types of organisms are found on the earth and they are dependent on each other and on the biosphere for their survival.

The biosphere contains organisms that can be divided into plant kingdom and animal kingdom. The lithosphere, the hydrosphere and the Atmosphere interact with each other and in different ways.

For example, Humans clean land for agricultural purposes, Animals depend on each other and on the plants for their food, plants depend on gases present in the Atmosphere, soil and sunlight for food.

Geography NCERT Notes For UPSC IAS Preparation

Ecosystem

Human beings, plants and animals depend on each other and their surroundings to fulfil their needs. They are interconnected to each other. This makes a relation between them. Thus, this relation between the living organisms with each other and also with the surroundings is known as an ecosystem.

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