Composition, Layer and Importance of Atmosphere
The Atmosphere: Our Life-Saving Blanket
The Earth is surrounded by a vast envelope of air known as the atmosphere. It acts like a
protective blanket that keeps our planet warm, shields us from harmful solar radiation, and
provides the essential gases needed for life. Without this thin layer of gases, Earth would be
a barren, lifeless rock—similar to the Moon.
Composition of Air
The air around us might seem invisible and uniform, but it’s actually a mixture of several
gases, along with water vapour and dust particles. These components vary slightly from
place to place and time to time, but the main gases remain nearly constant.
Major Components of Air
Nitrogen (N₂) – 78%
• Nitrogen is the most abundant gas in the atmosphere.
• It doesn’t directly support life but plays a vital role in maintaining the balance of
nature.
• Plants use nitrogen indirectly after it’s fixed into compounds by bacteria or lightning.
Oxygen (O₂) – 21%
• The second most abundant gas and essential for life.
• All living organisms use oxygen for respiration, and it is also necessary for combustion
(burning).
, Argon (Ar) – 0.93%
• A noble gas that does not react easily with other substances.
• It helps maintain the stability of the atmosphere.
Carbon Dioxide (CO₂) – 0.04%
• Although present in small amounts, it is very important.
• Plants use CO₂ during photosynthesis to make food and release oxygen.
• It also helps trap heat in the atmosphere, acting as a greenhouse gas.
Other gases – traces
• These include neon, helium, krypton, xenon, and hydrogen in very small quantities.
Variable Components of Air
These components vary depending on the time, place, and weather conditions.
Water Vapour
• Comes from the evaporation of water bodies.
• Responsible for humidity, cloud formation, and rainfall.
Dust and Smoke Particles
• Tiny particles of soil, ash, pollen, and pollutants remain suspended in the air.
• These particles help in condensation—the process by which clouds form.
The Atmosphere: Our Life-Saving Blanket
The Earth is surrounded by a vast envelope of air known as the atmosphere. It acts like a
protective blanket that keeps our planet warm, shields us from harmful solar radiation, and
provides the essential gases needed for life. Without this thin layer of gases, Earth would be
a barren, lifeless rock—similar to the Moon.
Composition of Air
The air around us might seem invisible and uniform, but it’s actually a mixture of several
gases, along with water vapour and dust particles. These components vary slightly from
place to place and time to time, but the main gases remain nearly constant.
Major Components of Air
Nitrogen (N₂) – 78%
• Nitrogen is the most abundant gas in the atmosphere.
• It doesn’t directly support life but plays a vital role in maintaining the balance of
nature.
• Plants use nitrogen indirectly after it’s fixed into compounds by bacteria or lightning.
Oxygen (O₂) – 21%
• The second most abundant gas and essential for life.
• All living organisms use oxygen for respiration, and it is also necessary for combustion
(burning).
, Argon (Ar) – 0.93%
• A noble gas that does not react easily with other substances.
• It helps maintain the stability of the atmosphere.
Carbon Dioxide (CO₂) – 0.04%
• Although present in small amounts, it is very important.
• Plants use CO₂ during photosynthesis to make food and release oxygen.
• It also helps trap heat in the atmosphere, acting as a greenhouse gas.
Other gases – traces
• These include neon, helium, krypton, xenon, and hydrogen in very small quantities.
Variable Components of Air
These components vary depending on the time, place, and weather conditions.
Water Vapour
• Comes from the evaporation of water bodies.
• Responsible for humidity, cloud formation, and rainfall.
Dust and Smoke Particles
• Tiny particles of soil, ash, pollen, and pollutants remain suspended in the air.
• These particles help in condensation—the process by which clouds form.
