What is Air?
Everything that takes up space is classified as matter. Air is unavoidable for our existence. The atmosphere is a blanket of air that covers the world. It is among the most vital elements for the existence of life since no life can survive for a single pulse of time without it. It is necessary for all creatures to survive. Let us learn about “what is air made of” and air composition. Also, air influences abiotic environmental components such as wind, rain, and climate.
The atmosphere, usually known as air, is a combination of different gases. When we think of air, the first thing that comes to mind is oxygen, which is necessary for life on earth to survive. However, oxygen is not the only important gas present in the air. Other gases are equally crucial in the maintenance of life. Let's take a closer look at the composition of the air that allows life to exist on earth.
Air Composition in Atmosphere
The atmosphere of the Earth is made up of a combination of gases called air. These gases are colourless and odourless. In the atmosphere, these gases combine to form a mixture of gases. It is made up of 78 % nitrogen, 21% oxygen, and 1 % other gases and water vapour. As we move up through the levels of the atmosphere, the composition of the air does not change. The number of molecules present in the air is what changes. The number of air molecules decreases and becomes smaller, as we go up. The moisture content varies from location to location. As compared to wetlands, arid places have less moisture content. The amount of water vapour or moisture in the air fluctuates. Air's maximum moisture carrying capacity is primarily determined by temperature. Until you reach a height of around 10,000 m, the composition of the air remains unchanged.
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Percentage of Gases in Air
Nitrogen is the most abundant naturally occurring gas, accounting for approximately 78% of air. With a prevalence of roughly 21%, oxygen is the second most abundant gas in the air. Argon, an inert gas, accounts for 0.93 % of the total composition. The atmosphere contains trace amounts of carbon dioxide, neon, helium, methane, krypton, hydrogen, nitrous oxide, xenon, ozone, iodine, carbon monoxide, water vapours, and ammonia. Now, let us talk about how these gases are produced and their various roles in our environment.
Nitrogen: Nitrogen makes up 78% of the air in the atmosphere. The nitrogen cycle transfers nitrogen to plants, animals, and the environment.
Nitrous Oxides: When nitrogen oxides interact with water droplets in the air, they produce nitric acid, which contributes to acid rain.
Oxygen: Oxygen accounts for 21% of the atmosphere. It is extremely reactive and forms compounds with a wide range of other chemicals, and it is required for living creatures to breathe.
Ozone: The ozone layer, formed by ozone gas in the stratosphere, is critical for the survival of life on Earth's surface.
Argon: Argon makes up around 1% of the atmosphere and is mostly produced by the breakdown of potassium in the Earth's crust. It does not react with other substances since it is an inert gas.
Water Vapours: Water circulates through all of Earth's systems in its three states, solid, liquid, and gas. Since it can trap heat, water vapour in the atmosphere acts as a greenhouse gas.
Carbon Dioxide: Carbon dioxide makes up about 0.03 % of the atmosphere naturally, but it is growing as a result of the combustion of fossil fuels. Carbon dioxide is used by plants and eubacteria during photosynthesis. Through breathing, humans, other animals, and plants contribute to the air. It is a heat-trapping greenhouse gas.
Carbon Monoxide: Carbon monoxide in the atmosphere is caused by the combustion of gasoline in automobiles, volcanoes, and forest fires. It's a lethal gas.
Methane: Landfills, animals and their manure, and oil and gas wells, all emit methane gas into the atmosphere. It is also produced during the decomposition of organic matter. It is a heat-trapping greenhouse gas.
Sulphur Dioxide: When coal and oil are burnt, sulphur oxides are created. It is also emitted by volcanoes. Sulphuric acid is formed when sulphur oxides in the atmosphere react with water droplets. Sulphuric acid is a component of acid rain.
Various Properties of Air
As already stated, gases are matter. Gases, like every other matter, have particular features. The following are some examples of frequent properties.
Colourless and Odourless: Air is usually colourless and odourless. It's an impenetrable substance that can only be felt. All living things require oxygen to survive. Moving air is referred to as wind.
Occupy Space: It is a blend of many gases. As a result, they, like all matter, occupy space. A balloon expands when blown because the air poured into it fills the empty area.
Exerts Pressure: It has weight, and air pressure is the force exerted by the weight of air. This combination of gases near the surface is denser than at high elevations due to gravity. That explains why the gaseous atmosphere is thinner in the mountains than at ground level.
Expansion: Another feature is its ability to grow. It expands and takes up more area when heated. As a result, the pressure of the warm wind is lower than that of cold wind.
FAQs on Air
1. What is the exact composition of the air in our atmosphere?
The air in Earth's atmosphere is a mixture of several gases, essential for life. Its composition is primarily:
- Nitrogen (N₂): Approximately 78%
- Oxygen (O₂): Approximately 21%
- Argon (Ar): About 0.93%
- Carbon Dioxide (CO₂): Around 0.04%
It also contains trace amounts of other gases like neon, helium, and methane, along with variable amounts of water vapour and dust particles.
2. What are the different layers of the atmosphere, starting from the Earth's surface?
The atmosphere is structured in five distinct layers, each with unique characteristics:
- Troposphere: The lowest layer where all weather phenomena, such as rain, fog, and clouds, occur. Temperature decreases as you go higher.
- Stratosphere: Contains the ozone layer, which protects us from the sun's harmful ultraviolet (UV) radiation.
- Mesosphere: This is where most meteors burn up upon entering the atmosphere. It is an extremely cold layer.
- Thermosphere: Characterised by a rapid rise in temperature. It helps in radio transmission as it contains electrically charged particles called ions (ionosphere).
- Exosphere: The uppermost layer, which gradually merges with outer space. It has very thin air.
3. What is the main difference between weather and climate?
The primary difference between weather and climate lies in the timescale over which they are measured.
- Weather refers to the short-term, hour-to-hour or day-to-day condition of the atmosphere. For example, a rainy day or a sunny afternoon describes the weather.
- Climate describes the average weather conditions of a place over a very long period, typically 25 years or more. For example, stating that a desert region is hot and dry describes its climate.
4. What exactly is air pressure and how does it change with altitude?
Air pressure is the pressure exerted by the weight of the air column on the Earth's surface. At sea level, the air pressure is highest because the entire weight of the atmosphere is pressing down. As you go up in altitude, the amount of air above you decreases, and therefore, the air pressure also decreases. This is why the air feels 'thinner' at high elevations.
5. What are the three main types of winds found on Earth?
Winds can be broadly divided into three major categories based on their characteristics:
- Permanent Winds: These winds, also known as planetary winds, blow consistently throughout the year in a particular direction. Examples include the Trade Winds, Westerlies, and Polar Easterlies.
- Seasonal Winds: These winds change their direction in different seasons. The best example is the monsoon winds in India.
- Local Winds: These winds blow only during a particular period of the day or year in a small area. Examples include the hot and dry 'Loo' in northern India during summer, and land and sea breezes near coastal areas.
6. Why is the atmosphere so important for life on Earth?
The atmosphere is critical for survival for several reasons beyond just providing air to breathe. It provides oxygen for respiration and carbon dioxide for photosynthesis. The ozone layer within the stratosphere shields all life from the Sun's harmful UV radiation. Furthermore, the atmosphere acts like a blanket, trapping heat and maintaining a stable temperature on Earth, preventing extreme heat during the day and freezing cold at night.
7. Why do mountaineers need to carry oxygen cylinders at high altitudes?
Mountaineers require oxygen cylinders because as altitude increases, the air pressure decreases. This means the air becomes less dense, and the oxygen molecules are more spread out. For every breath a person takes at a high altitude, they inhale fewer oxygen molecules than at sea level. This can lead to a dangerous condition called hypoxia. The supplementary oxygen from the cylinders ensures that their bodies get the required amount of oxygen to function properly.
8. How do winds help in regulating the Earth's temperature?
Winds play a crucial role as a global heat distribution system. Air moves from high-pressure areas to low-pressure areas. The equatorial regions receive more direct sunlight and are hotter, creating low-pressure zones. The polar regions are colder, creating high-pressure zones. Winds move this warm air from the equator towards the poles and cold air from the poles towards the equator. This circulation prevents the equator from getting progressively hotter and the poles from getting progressively colder, thus regulating global temperatures.
9. What is the scientific reason for the sky appearing blue?
The sky appears blue due to a phenomenon called Rayleigh scattering. Sunlight is composed of a spectrum of colours. When this light enters the Earth’s atmosphere, it collides with the tiny gas molecules and dust particles in the air. Blue light has a shorter wavelength and is scattered more effectively in all directions by these particles than other colours like red and yellow, which have longer wavelengths. Because blue light is scattered all over the sky, the sky appears blue to our eyes.
10. What is the relationship between temperature and air pressure?
Temperature and air pressure have an inverse relationship. When air is heated, it expands and becomes lighter (less dense). This light air rises, creating an area of low pressure below. This is common in hot, equatorial regions. Conversely, when air is cold, it is denser and heavier. This cold, heavy air sinks, creating an area of high pressure on the ground, which is typical of colder, polar regions.
