Definition, Characteristics, Importance of air

Meaning of air

Air is a mixture of different gases found in the atmosphere. These gases include oxygen, carbon dioxide, and nitrogen. A human being can feel air.

Characteristics of air

1. It is invisible.
2. It occupies space.
3. It is in a gaseous state.
4. It has neither smell nor color.
5. It has weight.

Pupils demonstrating the characteristics of air

Importance of air

Air is of great importance to the environment and living things. The importance of air is seen in the life of living things, burning of things, and pollination. Air is also important in the production of electricity, drying of materials and transfer of sound waves. Other areas in which air is important include rising and floating of things, and inflating of tyres and balloons. Likewise, air is important in changing atmospheric vapour into rain and balancing of heat on the earth.

1. Life for living things: All living things, including plants and animals, depend on oxygen for their life. A germinating seed uses oxygen to break down the stored food resulting into the production of energy. This energy is necessary for germination and growth of the plant. Plants also use carbon dioxide to manufacture their food. Similarly, in animals, oxygen is transferred through the blood to the cells. In the cells, oxygen helps to convert food into energy required by the body.

2. Burning of things: In order for fire to start, there must be oxygen gas. This gas allows the burning of different things such as firewood, charcoal, and paper. Fuel machine engines use oxygen for burning the fuel in order to produce energy. This energy enables the engines to work. In charcoal making, oxygen is restricted from entering the charcoal furnace. This is done to avoid the complete burning of charcoal to ash.

3. Pollination: The moving air in the atmosphere is called wind. This wind transfers pollen from the male part to the female part of the flower. This is done within the same plant or between one plant and another. Flowers produce a smell that is transferred by air from one place to another. The smell is sensed by living things such as insects and birds. The smell attracts insects and birds that are searching for food. In getting the nectar, they carry pollen and cause pollination in the flowers.

4. Production of electricity: There are different sources of electricity including hydroelectric power and solar energy. Electricity can also be produced by wind. Special power plants for the production of wind electricity are installed in strong wind places. The produced electricity is used in homes, schools, offices and factories.

Wind farm for producing electricity

5. Temperature regulation on the earth surface: Air circulates on the earth's surface and on water bodies such as rivers, lakes, seas and oceans. When sun rays hit some parts of the earth, especially during the dry season, the temperature rises. At the same time, water gains heat slowly hence it becomes relatively cooler than the land. Wind blows from water bodies to the land. Air from water bodies cools the air on the land. Air circulation between water bodies and the land regulates the temperature of the earth.

6. Drying of things: Circulating air absorbs water vapor (moisture) from different things such as crops and soil. Exposure of wet clothes at open places allows air to absorb the moisture. In this case, air causes drying of the clothes. Cereal crops are spread at open places so that the circulating air can take away the moisture for proper drying of the crops. Examples of cereals that can be dried by air are maize, millet, sorghum and beans.

Maize dried in air

7. Transfer of sound waves: Presence of air enables one to hear voices from human beings, birds, animals and different things such as bells. Sound waves travel from the points of their production to other places through air. For example, a radio receives different sound waves from broadcasting stations. Without air, you could not hear the voices you always hear in your environment.

8. Rising and floating of things: Birds and different insects move from one place to another by flying. Things that fly have special features that enable them float in the sky. Parachutes and balloons are inflated with air for them to float in the sky. Likewise, some of the objects that float on water such as buoys contain air that makes them float.

A parachute floating in the sky

9. Change of atmospheric vapor into rain: When water from different bodies gains heat, it changes into vapor that rises into the atmosphere. In the atmosphere, water vapor cools and condenses into clouds. When the clouds become heavy they fall as droplets which are called rain. The whole cycle of forming rain mainly depends on air.