Class 9 Science: Air Movement And How It Influences Rains And Climates

One thing that is present all around us, even though we might not be attentive to it, is air. It comprises various colourless and odourless gases that cannot be identified easily, and hence its presence becomes unnoticeable. This air makes up the atmosphere of our planet and is essential to multiple phenomena. The mixture of gases is present in different concentrations. Nitrogen makes up 78 per cent of our atmosphere, while oxygen makes up 21 per cent.

This Story also Contains

1. What Causes The Movement Of Air?
2. Heat Waves And Cool Breeze
3. Air Movement And Rain
4. How Does Atmospheric Circulation Regulate Climates?
5. Changes In The Air Movement Due To Altered Temperature
6. Impact Of Altered Air Movements

Air movements arise when there are changes in pressure and temperature. This brings about changes in the weather and the climate of the region. When pressure or temperature differences trigger a movement, it is called wind.

What Causes The Movement Of Air?

The main cause of air movement is the difference in air density. Warm air has lower pressure, and thus it rises, whereas cold air, having a higher density, sits lower in the atmosphere.

Solar radiation has an important role in triggering air movements. When it heats the air and land, the heat dissipates in the wind and is carried across the region. Therefore, wind also carries heat and water vapour with it, which greatly affects the weather and climate of a region.

Other than temperature and pressure, the tendency of air to attain equilibrium also triggers air movement. Cold air moves above the region of lower pressure to maintain equal pressure.

Temperature is an important influence on air movement because lower temperatures support less water vapour in the air, while higher temperatures add more vapour. Therefore, hotter areas have more humidity.

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Heat Waves And Cool Breeze

When the temperatures are abnormally high, especially in the summer, then land and water bodies are extremely heated. This leads to more humidity; however, the water dries up and becomes dry, but hot air flows throughout the region.

A cool breeze blows when the air carries water and the land is heated up. Due to heating, the air pressure is higher, so a gentle wind blows near the land to maintain pressure equilibrium.

Air Movement And Rain

When the sun radiates heat, water from the water bodies evaporates, and these water vapours are added to the air. As the temperature goes up, the amount of water vapour increases, which the air cannot hold after a certain point and thus leads to condensation. As the water content increases, it triggers precipitation.

So, the cycle of evaporation, condensation, and precipitation is carried forward due to the air and its movement.

The moisture in the air could be held only until a certain limit. When the moisture-laden air flows through the land, it gets more heated, thereby increasing water vapour and ultimately water. This water falls as rain on the land.

However, when the air moves to mountains or other colder regions, all the moisture from the air is already lost in the hotter areas. Due to this, mountains like the Himalayas or colder regions like Ladakh receive as little as 100 millimetres of rainfall.

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How Does Atmospheric Circulation Regulate Climates?

Hot and cool breezes are the types of winds that influence the climate and weather of regions. Sometimes the winds can be so powerful that they manifest as hurricanes and cause harmful effects.

Atmospheric circulation is an important phenomenon because it explains the workings of the Earth's System. This circulation, along with ocean circulation, is extremely influential in deciding the climate of a particular region. This can be explained by the breeze exchange between hot air over land and cooler air over the ocean in the daytime. On the contrary, warmer oceans at night have lower pressure, while the land breeze is cooler and thus drawn towards the ocean for equilibrium.

Changes In The Air Movement Due To Altered Temperature

Recently, global warming has worsened the condition of the planet. The heat absorption has increased due to the greenhouse gases, and thus the overall temperature and pressure of the air have changed. This has led to unexpected breezes and even hurricanes in different regions.

Some regions are experiencing untimely rainfall and other disasters as the atmospheric circulation has been disturbed. The air movements carrying the heat and moisture are disturbed, due to which situations like heavy rainfall, drought, floods, and more are more prevalent.

Impact Of Altered Air Movements

Air movements and their alteration can lead to many disturbing effects on nature and mankind. Heat waves affect the health of organisms, leading to some fatalities. The untimely weather and seasons have been interrupting natural phenomena, leading to altered agriculture, vegetation, and more.

Health concerns have been raised dramatically because of the unexpected season’s timeline. Rains in the summer season have caused many infections and other diseases because extreme heat followed by rain breeds many problems. The body does not adapt to sudden temperature changes, and hence people suffer due to weather changes.

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