Description: This chapter deals with the major domains of the earth which are lithosphere, atmosphere, hydrosphere together forming the biosphere, which ultimately makes life possible on earth.
Major Domains of the earth: The three different life-giving components on the earth are:
1. Land
2. Water
3. Air
These three components are essential for the survival of living beings on earth. The three components are also known as the lithosphere which consist of rocks, Hydrosphere which consists of the water bodies and the atmosphere which constitute of gases and water vapour. These domains together make up the live supporting Biosphere, the zone which is habitable by humans, animals and plants.
Figure 1: Showing the major domains of the earth
- Lithosphere: The outer part of the earth consists of plates which are covered by hard rocks and soil. This zone makes it possible for the human being or terrestrial animals to survive. There is approximately 1/3 portion of the earth which is covered by the lithosphere, while the rest is covered by the oceans. All important activities such as agriculture, settlement, building industries take place on the hard layer which is known as the lithosphere. Many burrowing animals also digs deep into the soil and survives within this lithosphere. The lithosphere thus gives rise to the various continents.
- Continents: Continents are large landmasses which occur on the lithosphere. The continents are divided into various countries and states. A list of continents according to their size is given below:
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Figure 2: Showing the layers of the earth
- Hydrosphere: The hydrosphere is the domain which constitutes all the water on the earth. Water can either be present as fresh water in the rivers, lakes ponds or water can be saline as in the seas and oceans. It can also be present within the lithosphere as underground water. Any form of water which is present on the earth therefore is a part of the hydrosphere. A list of constitutes which form the hydrosphere is given in a table below:
Water masses at Earth’s surface
oceans
ice caps, glaciers, and permanent snow
ground ice and permafrost
groundwater
lakes
soil moisture
swamp water
rivers
- Oceans: Oceans constitute the greatest volume of water within the hydrosphere. Ocean water is saline and thus cannot be consumed by human or animals. However, the ocean play a vital role in controlling the climate of the earth, in storing the carbon dioxide and maintain all the biogeochemical cycles. Fishes, lobsters, crabs and many other animals are consumed from the oceans. It is a treasure house for many minerals present in the earth. A list of oceans of the earth are given below:
List of Oceans
- Pacific Ocean.
- Atlantic Ocean.
- Indian Ocean.
- Antarctic Ocean (Southern Ocean)
- Arctic Ocean.
Figure 3: showing the hydrosphere
- Atmosphere:
The atmosphere is the outermost layer of the Earth comprising of various gases such as the nitrogen, oxygen, water vapour, carbon dioxide, ozone etc. These gases are retained by Earth’s gravitational force. Many dust and particulate matter are also present within this domain. All the weather phenomenon occurs within this zone. Clouds which form due to the water vapour occurs in the lower most layer of the atmosphere. The atmosphere is further categorized into different layers.
Figure 4: Showing the composition of gases in the atmosphere
Figure 5: different layers of the atmosphere
- Troposphere
The troposphere is the lowest layer of our atmosphere. Starting at ground level, it extends upward to about 10 km above sea level. We humans live in the troposphere, and nearly all weather occurs in this lowest layer.
- Stratosphere
The next layer up is called the stratosphere. The stratosphere extends from the top of the troposphere to about 50 km above the ground. All the aeroplanes fly in this layer as there is no weather disturbance.
- Mesosphere
Above the stratosphere is the mesosphere. It extends upward to a height of about 85 km above our planet. Most meteors burn up in the mesosphere..
- Thermosphere
The atmosphere partially vanishes in this later. All the Sun’s rays are first absorbed within this layer. Temperatures within Thermosphere are extreme, it is either too cold or too hot. There is no weather phenomenon in this layer.
Figure 6: Showing the interaction between the land, air and water
- Biosphere – the domain of life: The biosphere, is the layer within the planet Earth where life exists. This layer ranges from heights of up to ten kilometres above sea level, to depths of the ocean. The ranges are determined according to the zones which helps life to sustain, has water and oxygen. This biosphere is an integral part of all the domains as it is the only sphere sustaining life. Energy received from the sun allows the trophic levels of different orgasms to survive.
Figure 7: Biosphere interaction with the other domains
The major domains of the earth, viz. lithosphere, atmosphere, hydrosphere all function together to make the biosphere, which sustains life on earth. Earth is also thus known as the only planet sustaining life due to the presence of the biosphere.