Major domains of the earth are a basic concept in Geography. The earth’s surface is a complex zone in which the three major components of the environment meet, overlap and interact.
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.
The solid portion of the earth on which we live—
- Comprises the rocks of the earth’s crust and the thin layers of soil that contains nutrient elements which sustain organisms
- Continents- large landmasses
- Ocean basins- the huge water bodies
There are seven major continents and these are separated by large water bodies.
- Asia is the largest continent covering one-third of the total land area of the earth.
- The continent lies in the Eastern Hemisphere.
- The Tropic of Cancer passes through Asia.
- The Ural Mountains on the west separates from 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.
- 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.
- North America
- North America is the third largest continent in the world.
- The continent lies completely in the Northern and Western Hemisphere.
- The Isthmus of Panama a narrow strip links North America and South America.
- This continent is surrounded by three oceans and they are the Atlantic Ocean, the Pacific Ocean, and the Arctic Ocean.
- 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.
- 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.
- 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.
The gaseous layers that surround the earth— where oxygen, nitrogen, carbon dioxide and other gases are found and interact
- Provides the air we breathe + Protects us from the harmful effects of sun’s rays
- The changes in the atmosphere produce changes in the weather and climate
- Extends up to a height of about 1,600 kilometres
- The gravitational force of the earth holds the atmosphere around it
- Divided into five layers based on composition, temperature and other properties— troposphere, the stratosphere, the mesosphere, the thermosphere and the exosphere.
- Composed mainly of—
- Nitrogen and oxygen, which make up about 99 per cent of clean, dry air.
- Nitrogen (helps in the growth of living organisms) 78 per cent, oxygen 21 per cent and other gases like carbon dioxide, argon and others comprise 1 per cent by volume
- Carbon dioxide: Present in minute amount but is important as it absorbs heat radiated by the earth, thereby keeping the planet warm and also essential for the growth of plants.
- The density of the atmosphere: Maximum at the sea level and decreases rapidly as we go up
- Wind: Moves from high pressure to low pressure
- The earth is called the blue planet.
- More than 71 per cent of the earth is covered with water and 29 per cent is with the land. Hydrosphere consists of water in all its forms.
- More than 97% of the Earth’s water is found in the oceans and is too salty for human use.
- Hydrosphere consists of water in all its forms like running water in oceans and rivers and in lakes, ice in glaciers, underground water and the water vapour in the atmosphere.
- 97% of the Earth’s water is found in the oceans and is too salty, the rest of the water is in the form of ice sheets and glaciers or under the ground and a very a small percentage is available as freshwater for human use
- The three chief movements of ocean waters are the waves, the tides and the ocean currents.
- Oceans are the major part of the hydrosphere and they are all interconnected.
- The five major oceans in order of their size are
- the Pacific Ocean: It is almost circular in shape. Asia, Australia, North and South Americas surround it.
- the Atlantic Ocean: It is the second-largest ocean in the world. It 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 Indian Ocean: It 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: It surrounds the continent of Antarctica
- the Arctic Ocean: It is located within the Arctic Circle and surrounds the North Pole. The Barring strait a narrow stretch of shallow water connects it with the Pacific Ocean.
Biosphere – The Domain of Life
- The biosphere is the narrow zone of contact between the land, water and air.
- It is the zone where life exists that makes this planet unique.
- The organisms in the biosphere are commonly divided into:
- the plant kingdom
- the animal kingdom
- The three domains of the earth interact with each other and affect each other in some way or the other.
Strait: A narrow passage of water connecting two seas or two other large areas of water.
1. Malacca Strait
Joins: Andaman Sea & South China Sea
Location: Indonesia –Malaysia
2. Palk Strait
Join: Palk Bay & Bay of Bengal
Location: India-Sri Lanka
3. Sunda Strait
Join: Java Sea & Indian Ocean
4. Yucatan Strait
Join: Gulf of Mexico and Caribbean Sea
5. Mesina Strait
Join: Mediterranean Sea
6. Otranto Strait
Join: Adriatic Sea & Ionian Sea
7. Bab-el-Mandeb Strait
Join: Red Sea & Gulf of Aden
8. Cook Strait
Join: South Pacific Ocean
Location: New Zealand (North & South Islands)
9. Mozambique Strait
Join: Indian Ocean
Location: Mozambique -Malagasy
10. North Channel
Join: Irish Sea & Atlantic Ocean
11. Taurus Strait
Join: Arafura Sea & Gulf of Papua
Location: Papua New Guinea — Australia
12. Bass Strait
Join: Tasman Sea & South Sea
13. Bering Strait
Join: Bering Sea & Chuksi Sea
14. Bonne-Fasio Strait
Join: Mediterranean Sea
Location: Corsika — Sardinia
15. Bosporous Strait
Join: Black Sea and Marmara Sea
16. Dardenleez Strait
Join: Marmara Sea and Agean Sea
17. Davis Strait
Join: Baffin Bay & Atlantic Ocean
18. Denmark Strait
Join: North Atlantic and Arctic Ocean
19. Dover strait
Join: English Channel & North Sea
20. Florida Strait
Join: Gulf of Mexico and Atlantic Ocean
21. Hormuz Strait
Join: Gulf of Persia & Gulf of Oman
22. Hudson strait
Join: Gulf of Hudson & Atlantic Ocean
23. Gibraltar Strait
Join: Mediterranean Sea & Atlantic Ocean
24. Magellan strait
Join: Pacific and South Atlantic Ocean
25. Makkassar Strait
Join: Java Sea & Celebeze Sea
26. Tsungaru Strait
Join: Japan Sea and Pacific Ocean
Location: Japan (Hokkaido-Honshu Island)
27. Tatar Strait
Join: Japan Sea & Okhotsk Sea
Location: Russia (East Russia-Sakhalin Islands)
28. Fovex Strait
Join: South Pacific Ocean
Location: New Zealand (South Island- Stewart Island)
29. Formosa Strait
Join: South China Sea & East China Sea
Isthmus: A narrow strip of land with sea on either side, forming a link between two larger areas of land. The Isthmus of Panama is a narrow strip of land at the southernmost end of Central America. It lies between the Pacific Ocean and the Caribbean Sea while linking North and South America.