What Is Atmosphere?/ Layers of the Atmosphere / What Would Happen if Earth’s Atmosphere Disappeared?/ Composition of the Atmosphere

 

The Atmosphere

An atmosphere contains the air that we breathe. It is a blanket of gases that surrounds Earth and is held close to the planet by Earth’s gravitational pull. Without the atmosphere, life could not exist.

A barometer is the instrument used to measure air pressure.

The three main gases in our atmosphere are nitrogen, oxygen, and argon.

In this article by HN Series, let’s explore the atmosphere in the easiest and most exciting way!

What Is Atmosphere?

The atmosphere is a protective blanket of gases surrounding Earth.

It keeps us warm, allows us to breathe, and protects us from harmful solar rays.

Definition

“Atmosphere is a protective layer of gases that shelters all life on Earth, keeps temperatures balanced, and blocks harmful rays from the Sun.”

Features of the Atmosphere

• Keeps Earth warm by trapping some of the Sun’s heat

• Shields us from harmful UV radiation

• Plays a key role in the water cycle

• Helps keep the climate moderate

• Has no exact outer boundary—it slowly becomes thinner until it merges with space

Layers of the Atmosphere

The atmosphere is made of five major layers, each with unique features.

1. Troposphere (0–10 km)

• Lowest layer where all weather happens

• Contains 75% of all air

• Most clouds form here

• Temperature decreases as you go up

• The top boundary is called the tropopause

2. Stratosphere (10–50 km)

• Lies above the troposphere

• Contains the ozone layer, which absorbs harmful UV rays

• Temperature increases with height

• Jet planes often fly here because of less turbulence

3. Mesosphere (50–85 km)

• Meteors burn up in this layer

• The coldest layer of the atmosphere (can reach –90°C)

• Temperature decreases as altitude increases

4. Thermosphere (85–800 km)

• Very thin air, but extremely hot (up to 2,000°C or more)

• Auroras (Northern & Southern Lights) occur here

• Satellites orbit Earth in this layer

5. Exosphere (Above 800 km)

• Outermost layer

• Gradually fades into outer space

• Air is extremely thin and atoms escape into space

Ionosphere

• Not a separate layer

• Found within parts of the mesosphere and thermosphere

• Contains charged particles created by the Sun’s radiation

• Important for radio communication

Summary of Layers

Region	Altitude (km)	Temperature (°C)	Key Features
Troposphere	0–11	15 to –56	Weather occurs here
Stratosphere	11–50	–56 to –2	Contains ozone layer
Mesosphere	50–85	–2 to –92	Meteors burn here
Thermosphere	85–800	–92 to 1200	Auroras occur here
Exosphere	800+	—	Blends into space

What Would Happen if Earth’s Atmosphere Disappeared?

Imagine Earth suddenly losing its atmosphere—what would happen?

• Birds and airplanes would fall because air supports flight

• The sky would turn pitch black

• No sound could travel—sound needs air

• All water on Earth would boil away into space

• All air-breathing organisms (including humans) would die instantly

The atmosphere is truly our shield of life.

Composition of the Atmosphere

The gases present in dry air and their approximate percentages:

• Nitrogen (N₂): 78.08%

• Oxygen (O₂): 20.95%

• Argon (Ar): 0.93%

• Carbon dioxide (CO₂): 0.038%

• Traces of neon, helium, hydrogen, nitrous oxide, ozone, etc.

• Water vapour varies but is typically 1% at sea level

These gases make life possible by supporting breathing, climate control, and plant growth.

 (FAQs)

1. What is the greenhouse effect?

It is the process where certain gases trap the Sun’s heat and keep Earth warm. Without it, Earth would be too cold for life.

2. Does the atmosphere have an ending point?

No exact boundary. It becomes thinner with height and slowly blends into outer space.

3. Why do planes fly in the stratosphere?

The stratosphere has less turbulence, making flights smoother and more fuel-efficient.

4. Which layer contains the ozone layer?

The stratosphere.

5. What instrument measures air pressure?

A barometer.

The atmosphere is one of Earth’s most important features—it protects, warms, and sustains all life. Understanding its layers and functions helps students appreciate the natural systems that support life on our planet.

Stay tuned to HN Series and FALL IN LOVE WITH LEARNING!