• Major domains of the earth are a fundamental idea in geography.
• The earth’s surface is where the three main components of the environment come together.
• These components are: solid (lithosphere), gaseous (atmosphere), liquid (hydrosphere), and biosphere.
• These parts are not separate, but they interact with each other.

The Four Domains of the Earth

• Lithosphere: The solid portion of the earth
• Atmosphere: The gaseous layers that surround the earth
• Hydrosphere: Water covers a very big area of the earth’s surface and this area is called the Hydrosphere
• Biosphere: It is the narrow zone where land, water, and air together are found.
• 

Lithosphere

• Lithosphere is the outermost part of the earth, made up of the upper mantle and crust.
• Tectonic plates are a part of the lithosphere.
• It has rigid properties.
• Pedosphere is the top part of the lithosphere and interacts chemically with the other major domains of the earth (hydrosphere, biosphere, atmosphere).
• The thickness of the lithosphere is approximately 100 km.

Continents

There are seven major continents and these are separated by large water bodies.

1. Asia:
   • Asia is the largest continent, covering a third of the earth’s total land area.
   • Asia is located in the Eastern Hemisphere.
   • The Tropic of Cancer passes through Asia.
   • The Ural Mountains separate Asia from Europe to the west.
2. Europe:
   • Europe is much smaller than Asia lying to the west of Asia.
   • The Arctic Circle passes through it.
   • Its three sides are bound by water bodies.
3. Africa:
   • Africa is the second-largest continent after Asia.
   • A large part of Africa lies in the Northern Hemisphere.
   • Africa is the only continent through which the Tropic of Cancer, the Equator and the Tropic of Capricorn pass.
4. North America:
   • North America is the world’s third largest continent.
   • North America is located entirely in the Northern and Western Hemisphere.
   • The Isthmus of Panama connects North America to South America.
   • North America is surrounded by three oceans: the Atlantic Ocean, the Pacific Ocean, and the Arctic Ocean.
5. South America:
   • South America lies mostly in the Southern Hemisphere.
   • It is surrounded by two oceans; the Pacific Ocean on the west and the Atlantic Ocean on the east and north.
6. 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.
7. Antarctica:
   • Antarctica is a huge continent and lies completely in the Southern Hemisphere.
   • The South Pole lies in the South Polar Region almost at the centre of this continent and is permanently covered with thick ice sheets.

Atmosphere

• It is a layer of gas that surrounds the earth.
• The atmosphere contains gases like oxygen, nitrogen, carbon dioxide, and others that interact.
• Changes in the atmosphere cause changes in weather and climate.
• The atmosphere extends up to a height of around 1,600 km.
• The earth’s gravitational force keeps the atmosphere in place.
• The atmosphere is divided into five layers based on composition, temperature, and other properties: troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
• 99% of the clean and dry air in the atmosphere is made up of nitrogen (78%) and oxygen (21%), with other gases (1%) such as carbon dioxide, argon, etc.
• The density of the atmosphere is highest at sea level and decreases as you go up.
• 

Hydrosphere

• The earth is known as the blue planet because 71% of the earth is covered in water (hydrosphere) and 29% is land.
• More than 97% of the earth’s water is found in the ocean and is too salty for human use.
• The hydrosphere consists of water in all forms: oceans and rivers, lakes, ice in glaciers, underground water, and water vapor in the atmosphere.
• Only a small percentage of the earth’s water is available as freshwater for human use.

Oceans

• The three main movements of ocean water are waves, tides, and ocean currents.
• Oceans are the largest part of the hydrosphere and are all interconnected.
• The five largest oceans are:
  1. Pacific Ocean: It is surrounded by Asia, Australia, North and South America, almost circular in shape. It is almost circular in shape.
  2. Atlantic Ocean: It is the second largest ocean. It is “S” shaped, flanked by North and South America on the western side and Europe and Africa on the eastern side.
  3. Indian Ocean: It is named after India, triangular shape, bound by Asia in the north, Africa in the west, and Australia in the east.
  4. Southern Ocean: It surrounds Antarctica.
  5. Arctic Ocean: It is located within the Arctic Circle, surrounds the North Pole, connected to the Pacific Ocean by the Bering Strait.
• 

Biosphere

• The biosphere is the part of the earth where life exists
• The biosphere is a narrow zone between land, water, and air
• The biosphere contains two main groups of organisms: the plant kingdom and the animal kingdom
• The biosphere interacts and affects the other three major domains of the earth: Lithosphere, Atmosphere, and Hydrosphere