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Earth is surrounded by an atmosphere. The atmosphere is the air around as that envelopes the planet and is responsible for making Earth suitable for sustaining all forms of life by providing us with the air for respiration and shielding us from the direct sun’s rays which can be damaging. The atmosphere consists of various gases, precisely 78% Nitrogen, 21% Oxygen, 0.9% Argon and 0.4% Carbon Dioxide. For the existence of human life these all gases play a coextensive role. Air is the most crucial thing which is responsible for the existence of all forms of life on Earth. Air contains oxygen, which is essential for the survival of human lives, combustion, etc.
Table of Contents
| Table of Content |
Key Terms: Air, Breathing, Combustion, Humans, Earth, Atmosphere, Temperature, Oxygen, Carbon Dioxide, Gases, Respiration, Ozone Layer, Photosynthesis
Why is Air Important?
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Air acts as a blanket that covers the Earth and supports life on Earth by helping in various life processes. Air plays a vital role in sustaining life on Earth, regulating the temperature of the Earth and helping in the process of Combustion.
The three main roles of Air are as follows:
- Air for Breathing
- Air for Combustion
- Air for Regulating Temperature
Composition of Air
Also Read: Importance of Air
Air for Breathing
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As we know oxygen is important for life, breathing is a process of taking air in and out through nostrils, called inhalation and exhalation respectively. The number of times a person breathes is called Breathing rate.
Similarly, plants take in carbon dioxide and sunlight which is available in abundance during the daytime, all green plants convert light energy into chemical energy. In this process, carbon dioxide molecules are converted into glucose molecules and in return, oxygen is released as a byproduct, this process is called Photosynthesis.
This oxygen is breathed in by all animals takes in for their existence. All living animals take in oxygen which is supplied to cells that helps in breaking down food and thus produces energy and as a byproduct carbon dioxide is released.
Process of Photosynthesis
Process of Respiration
As we intake air through our nose, it is passed by the nostrils into the cavity of the nose called the nasal cavity. Through the nasal cavity, the air reaches our lungs through the windpipe. Lungs are present in the chest cavity. This cavity is surrounded by ribs on both the sides. A large and muscular sheet known as a diaphragm forms the floor of the chest cavity. Breathing mainly involves the movement of the rib cage and the diaphragm.
During the process, ribs move up and outwards and the diaphragm moves down. This movement increases space in our chest cavity and air rushes into the lungs. The lungs get filled with air.
During exhalation, ribs move down and inwards, while the diaphragm moves up to its former position. This reduces the size of the chest cavity and the air is pushed out.
The Human Respiratory System
The air contains many unwanted particles such as smoke, dust etc. which are harmful to the lungs as they get stuck in the hair present in the nasal cavity, sometimes they fail to pass the cavity and the irritating sensation is the reason why we sneeze.
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Air for Combustion
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Combustion is a chemical process that involves a high-temperature process that releases heat energy and emits light which is why we see flames, the process involves the reaction of oxidant and fuel.
Coloured flames are observed when methane, which is an important part of the combustion reacts with the air present in the nearby atmosphere. This energy can be used to run cars, turbines, cooking etc.
Oxygen is highly inflammable and due to the abundance of oxygen in the atmosphere may cause blasts, here Nitrogen comes in rescue, and it prevents the oxygen to catch fire as 78% of the atmosphere is covered with Nitrogen.
Thus, for combustion to take place in a controlled manner, both Oxygen, as well as Nitrogen, is required.
Combustion
Air for Regulating Temperature of Earth
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Air gets heated by the radiation received from the sun, then the radiation is reflected back from the earth’s surface to escape to outer space. This causes heating of air mass, heating of air mass near the surface, lightens up the weight of the air mass, the relatively lighter air mass moves upwards, creating a void near the surface of the Earth, now this space is filled up by the colder air mass which is relatively heavier than the colder air mass.
- Convection- The continuous process and the lighter air moves upwards as convection current called convection.
- Advection current- The similar process is observed horizontally throughout the surface of the Earth called advection current.
This process is responsible for maintaining the Earth’s temperature suitable for the existence of life. The process is explained in the diagram below.
This heat which is received by the sun and reflected by the earth, cloud cover is maintained throughout the process called Heat Budget.
Earth’s Heat Budget
Things to Remember
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- Air is a mixture of gases that are vital for sustaining the various life forms present on the Earth. Air acts as a huge blanket that helps in the vital processes required for life.
- Air consists of various gases namely 78% Nitrogen, 21% Oxygen, 0.9% Argon and 0.4% Carbon Dioxide.
- Air is vital for mainly three processes- Breathing, Combustion and for Regulating the Temperature of the earth.
- Without air/atmosphere, the Earth would have been an extremely hostile, cold climate planet. The air helps to regulate and moderate the temperature of the Earth.
- Air helps in the process of the water cycle thus allowing the various forms of water to be present on the Earth.
Sample Questions
Ques. State the factors responsible for maintaining the temperature of the Earth. (3 Marks)
Ans. The temperature in the Earth is maintained to a certain level which makes the temperature sustainable for the existence of lives is mainly due to the radiation received by the Earth by the Sun and reflection of the radiation by the Earth’s surface, cloud cover, water bodies.
Through the process called convection and advection currents, the process is vertical and horizontal respectively.
Ques. How air is necessary for the process of combustion? (3 Marks)
Ans. Combustion is a chemical process that involves the combination of oxygen gas with fuel to release energy in the form of heat and light.
For the combustion reaction oxygen is the diving compound which causes the burning of fuel, oxygen is highly reactive, but the combustion in the atmosphere is
controlled by nitrogen which is the most abundant gas in the atmosphere, which constitutes about 78% of the total composition of the air.
Ques. What is the process of photosynthesis? (3 Marks)
Ans. The plants intake carbon dioxide through stomata, which with the help of sunlight prepare the glucose for their body. And as byproduct plants release oxygen which is important for the existence of human life.
In simpler terms, Photosynthesis is the process through which the plants prepare their own food with the help of carbon dioxide, water, sunlight, and chlorophyll to produce glucose and oxygen.
Ques. What causes turbulence in air crafts? ( 3 Marks)
Ans. The vertical movement of air is called convection. And the movement of air is in the form of Eddy Currents which causes turbulence in the air crafts. The circular eddy currents are formed due to the parcel of air replacing the other. The hotter parcel of air is replaced by the colder one and the colder parcel later settles down due to gravity. This all happens in circular motion called Eddy current.
Ques. Why do we observe blue coloured flame? (2 Marks)
Ans. Blue colour flame is due to the release of methane gas which reacts with the air present in the atmosphere. In a combustion process, the oxidant reacts with fuel to emit light thus heating the nearby environment.
Ques. What is respiration? (3 Marks)
Ans. Respiration is the process in which humans’ intake the air through their nasal cavity and the dust particles stays outside the cavity by the hair present in the nose. The air then slides down to the lungs where the ribs cage expands making space for the oxygen, and while exhaling the rib cage shrinks. This whole process is called respiration.
Glucose(C6H12O6) + Oxygen(6O2) → Carbon dioxide(6CO2) + Water(6H2O)+ Energy (ATP)
Ques. What is the composition of air? (3 Marks)
Ans. The air comprises several gases of which are all equally important but in a limited quantity, the air contains 78% of nitrogen which is essential as it prevents the combustion of oxygen in the air, 21% oxygen and 1% other gases.
There is around 0.9% Helium and 0.4 % Carbon Dioxide that is present as other gases. Oxygen is considered to be the most vital gases of all.
Ques. Why does air do not burn despite having 21% of oxygen? (3 Marks)
Ans. The answer to this is that Nitrogen acts as a resistance to the combustion of oxygen, which is present 78% in the atmosphere.
The uncontrolled use of oxygen is dangerous because oxygen is highly reactive, for example, the Nascent oxygen is highly flammable and a little spark may lead to a disastrous blast.
Ques. What is the vertical variation of the air mass called? Choose the correct option: (1 Mark)
A) Eddy Currents B) Convection current C) Advection currents D) None of the above
Ans. B) Convection Currents.
The continuous process and the lighter air moves upwards as convection current is called convection.
Ques. What are essential compounds for controlled combustion? Choose the correct answer. (1 Mark)
A) Carbon Dioxide B) Nitrogen C) Oxygen D) Both B & C
Ans. D) Both B&C
As oxygen is highly flammable and the combustion in the atmosphere is controlled by the nitrogen in the atmosphere.
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