The air around us forms the atmosphere of the earth. It extends from the ground to about 11 km into space. It gets denser due to the gravity as we approach the ground. It has the right amount of pressure and composition to sustain life. The atmosphere above the earth’s surface forms a blanket of gases protecting us from many harmful radiations that come from outer space. The three important roles of air are discussed below:
Air for Breathing
All life on land (barring a few species of bacteria) requires air to survive. It contains two essential components: Oxygen and Carbon dioxide which make this possible. Oxygen is required by plants and animals to convert the chemical energy stored in food into energy that they can use for all activities. In this process, oxygen is taken in and reacted with molecules from food to produce energy. In the process, carbon dioxide and water along with usable energy are released. This is known as respiration.
Plants also breathe in carbon dioxide in the presence of sunlight to store the energy of light as chemical energy in food. Plants convert the carbon dioxide molecule into glucose (food) molecules using sunlight. In the process, oxygen is released as a byproduct. This is known as photosynthesis.
Thus we need air to gain energy from food and plants need it to store energy in form of food. This balance sustains all life on earth.
Air for Combustion
Combustion is the process in which fuel combines with oxygen to release energy in the form of heat and light. We can use this heat to produce electricity, run our cars and cook food. During combustion oxygen in the atmosphere combines with carbon atoms to produce carbon dioxide and hydrogen atoms to produce water. In fact without oxygen one cannot use these fuels for our daily needs. However, too much oxygen can cause uncontrolled burning and explosions. Even the tiniest spark can set off fires everywhere. This does not happen because of another component present in the atmosphere: Nitrogen. 78% of air is nitrogen gas. Nitrogen does not support combustion and thus prevents the excess reactivity of oxygen. Thus these two components are essential to ensure that energy from the fuel can be used in a controlled manner.
Air for Regulating Temperatures
Upon heating, the density of air reduces and it rises upwards. Similarly, cold air is denser than the hot air which sinks towards the ground. As the hot air rises, it creates a space of low pressure where the cold air rushes in and occupy this space. This results in the movement of air called wind.
As the hot region heats up the air and gets raises, the colder air from the surroundings enters into it, get heats up and the cycle repeats. The rising of the hot air transfers its heat into outer space and sinks back down. In this way, heat is transferred from hotter regions to colder regions. This is known as temperature regulation and the process of transferring heat is called convection.
Without the atmosphere, the daytime temperatures on earth would be as very high and at night it would be as cold as -30⁰ C which would make it very difficult for life to survive. Thus the air keeps the temperature on earth moderate enough for life to exist.
Other natural resources like water, land, plants, rivers, mountains, etc. play a key role in sustaining life on earth by complementing each other. We always tend to take these resources for granted and due to population outburst, these resources are under great stress. Measures must be taken so that the coming generation too can enjoy the luxury of nature as we do.
To learn more about nature and the role of different components of nature in sustaining life on earth, visit Byju’s.
Practise This Question