Air Around Us: Air can be found all around us. Although we cannot see air, we may sense its presence in a variety of ways. Walking, for example, allows us to sense the presence of air. Have you ever considered how a kite flies? It flies because of the wind, which is moving air. What is the composition of this air? We’ve heard it’s a blend of several gases. What gases are these? What is the name of the air that surrounds you? What part of our lives does air play? What are its characteristics? What is the purpose of it? These aspects will be discussed in this article.

Atmosphere

The blanket of air that surrounds our earth is called the atmosphere. It is a gaseous envelope surrounding the earth which is retained by the gravitational field of the earth. From the sea level, it extends to about \(120\;\rm{km}\). It has five main layers such as the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The five main layers of the atmosphere can be described as,

1. Troposphere is the lowermost layer of the earth’s atmosphere. It extends around \(10\;\rm{km}\) above sea level. The troposphere is related to the weather processes such as thunderstorms, cloud formation, rainfall, and snowfall.
2. Stratosphere is the second layer of the atmosphere while going upward. It is around \(50\;\rm{km}\) from sea level. The ozone layer that protects us from the harmful ultraviolet radiations coming from the sun is present in stratosphere.
3. Mesosphere is the third layer of the earth’s atmosphere as we move up. From the sea level, it extends around \(80\;\rm{km}\). In this layer, the burning of meteorites when they enter into space takes place here.
4. Thermosphere is the fourth layer of the earth’s atmosphere as we move up. From the sea level, it extends up to \(80-450\;\rm{km}\). It is the layer that helps in radio transmission.
5. Exosphere is the last layer of the atmosphere as we go up. The gases such as helium and hydrogen float here.

Properties of Air

1. Air is the gaseous form of matter.
2. Air is colorless and transparent in nature. These are the reasons why we cannot see air.
3. Air is a form of matter. Therefore, it has mass, and it occupies space.
4. Air supports the process of burning.

Composition of Air

We have heard that air is a mixture of many gases. Which are these gases? Let us discuss them in detail.
Earlier, it was believed that air is a single substance. But later, some experiments proved that air contains different gases. That is, air generally has the gases such as nitrogen \((78\%)\), oxygen \((21\%)\), and other gases \((1\%)\) such as carbon dioxide, argon, ozone, water vapour, dust particles, etc.

Composition of Air Diagram

The composition of air can vary from place to place. For instance, the air is thinner on mountains compared to plains. Similarly, the percentage of oxygen in the air will be more in the places where greenery is high.
Let us discuss the importance of major components of air in detail.

1. Nitrogen: It is the most abundant gas in the earth’s atmosphere. The atmospheric air contains around \(78\%\) of nitrogen. It is required by animals and plants for their growth. The atmospheric nitrogen is also used for the production of fertilizers. The nitrogen gas will not support burning; it helps to control the process of burning.
2. Oxygen: We know that oxygen is called as life-supporting gas. Our atmospheric air contains around \(21\%\) of oxygen. All living things need oxygen. For example, while respiration, we need oxygen to breathe in and will use it to produce energy by breaking down the food. Oxygen is also necessary for the process of burning.
3. Carbon dioxide: Carbon dioxide is an important gas required for both plants and animals. Plants use carbon dioxide for the process of photosynthesis. It is also known as a greenhouse gas that helps to trap heat (greenhouse effect).
   Plants and animals use oxygen a lot. However, we never seem to run out of oxygen. Why is it so? Well, this is because there are some natural processes that helps to maintain the level of oxygen and carbon dioxide in the atmosphere. These processes are respiration and photosynthesis. That is, during the process of respiration, we inhale oxygen and exhale carbon dioxide. Similarly, during the process of photosynthesis, plants take in carbon dioxide and release out oxygen.
4. Water vapour: Air contains water vapor. The source of water vapor in the air is due to the phenomenon of transpiration and evaporation.
5. Dust and Smoke: Dust particles are always present in the air. The amount of dust particles in the air varies from place to place and from time to time. Air also contains smoke. This is given out by vehicles and factories. Dust and smoke in the air are harmful to our respiratory system.
6. Besides these gases, the other gases present in the atmosphere are generally called trace gases.
   
   Also Check,

Presence of Air Around Us

NCERT Solutions for Class 6 Science Chapter 15

Importance of Air

All living beings use air to live. Human beings need oxygen for the process of breathing. We know that air is present everywhere around us. Even water and soil contain air. This air present in soil and water supports life in them. Let us discuss them in detail.

How Air Supports Life in Water?

We know that water is called the universal solvent. Water contains air dissolved in it. The oxygen present in the water helps the aquatic plants and animals to survive. Similarly, the leaves of aquatic plants absorb oxygen from the water to prepare food. The aquatic animals have special organs through which they breathe the air dissolved in water.

How Air Supports Life in Soil?

Air is trapped in the particles of soil. The organisms such as earthworms, snails, insects, and other small animals living in the soil use this air trapped inside the soil. Do you know why we see so many insects and worms outside the soil during the rainy season? The reason for this is, the rainwater fills up the air spaces in the soil forcing the animals to come out to breathe.

Uses of Air

As discussed, all living things need air for their survival. Apart from this, the air is useful in many ways. They are:

1. Air allows the sound to travel. That is, air acts as a medium to carry sound.
2. Moving air, which is called wind, is used to run windmills that help to produce electric energy.
3. Clouds move with the help of moving air called wind.
4. Moving air helps in the process of winnowing.
5. Compressed air is filled in the tires of vehicles. This makes their movement possible.
6. The oxygen gas filled in cylinders is used for the process of artificial respiration.
7. Water vapour present in the air is an important constituent of the water cycle.
8. Wind also helps in the dispersal of seeds and pollen grains.
9. The atmosphere (the blanket of air that surrounds the earth) protects all living organisms from the harmful UV radiations coming from the sun.
10. Oxygen, a main constituent of air is necessary for the burning of fuels.
11. Wind helps in the movement of aeroplanes, gliders, parachutes, and sailboats.
12. Compressed air is also used in some machines that are used for crushing and digging stones.

Summary

We have now understood that air is a mixture of many gases which is present everywhere around us. The blanket of air that surrounds our earth is called the atmosphere. The atmospheric air contains the gases such as nitrogen \((78\%)\), oxygen \((21\%)\), and other gases \((1\%)\) such as carbon dioxide, water vapour, dust, smoke particles, etc.

However, the composition of the air varies from place to place. Nitrogen is the most abundant gas in the earth’s atmosphere, and oxygen is the second most abundant gas in the atmosphere, which is called the life-supporting gas. These gases are much needed for the survival of living organisms. Also, the other components of air are much useful in one or the other ways. Such uses and different properties of air are detailed in this article.

FAQs

Q.1. What is the meaning of air around us?
Ans: The meaning of air around is that air is a mixture of many gases that is present everywhere around us. It is a mixture of various gases.

Q.2. What are the uses of air?
Ans: Air has got many uses. The different components of air are important for the survival of living organisms. Also, the air is used as a medium for the sound to travel; moving air (called wind) is used in the process of winnowing, transport of pollen grains, windmills, etc., and the oxygen present in the air helps in the process of burning of fuels.

Q.3. What is air made up of?
Ans: Air is a mixture of many gases. That is, air generally has the gases such as nitrogen \((78\%)\), oxygen \((21\%)\), and other gases \((1\%)\) such as carbon dioxide, argon, ozone, water vapour, dust particles, etc.

Q.4. How do we feel the presence of air?
Ans: We can feel the presence of air in many ways, like the swaying of leaves on a tree. We feel the presence of air on our faces and arms while walking. Similarly, a kite files due to moving air or wind.

Q.5. How do we use air in our everyday life?
Ans: Air is essential for the survival of life on earth. For example, the oxygen present in the air is required for the process of respiration, where we breathe in oxygen and exhale out carbon dioxide. Similarly, for the process of photosynthesis, plants use the carbon dioxide present in the atmosphere and give out oxygen into the atmosphere.

Q.6. What is air and its importance?
Ans: Air is a mixture of many gases which is present everywhere around us. Air is important in many ways. It helps in the process of respiration, photosynthesis, combustion; it is used for the transfer of pollen grains, used to run windmills, used as a medium for sound propagation, etc.

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