Atmosphere

Atmosphere is a protective layer of gases that shelters all life on Earth, keeping temperatures within a relatively small range and blocking out harmful rays of sunlight.”

An atmosphere is a blanket of gases that surrounds Earth. It is held near the surface of the planet by Earth’s gravitational attraction. Argon, oxygen and nitrogen from the three main constitutions of the atmosphere.

The atmosphere:

  • contains the air that we breathe
  • helps retain the sun’s heat and prevents it from escaping back into space
  • protects life from harmful radiation from the sun
  • plays a major role in Earth’s water cycle
  • helps keep the climate on Earth moderate

There is no boundary between the atmosphere and outer space. The atmosphere gets less dense and denser until it “blends” into outer space.

Different Layers of AtmosphereVideo Explanantion of AtmosphereEarth without AtmosphereGases in the AtmosphereFrequently Asked Questions

Layers of Atmosphere

What do you see when you stand outside and lookup? A blue sky? A group of clouds? At night you might see a crescent moon, stars, a satellite. What you are not seeing, however, is the complexity of our atmosphere.

The atmosphere has five distinct layers that are determined by the changes in temperature that happen with increasing altitude. Layers of Earth’s atmosphere are divided into five different layers as:

  • Exosphere
  • Thermosphere
  • Mesosphere,
  • Stratosphere
  • Troposphere.

Let us find out more about the layers of atmosphere and their importance.

 

 

Layers of Earth's Atmosphere

The hierarchical arrangement of various layers of the Earth’s atmosphere

 

Troposphere

The troposphere is the lowest layer in the atmosphere. It extends upward to about 10kms above sea level starting from ground level. The lowest part of the troposphere is called the boundary layer and the topmost layer is called the tropopause. The troposphere contains 75% of all air in the atmosphere. Most clouds appear in this layer because 99% of the water vapour in the atmosphere is found here. Temperature and air pressure drop as you go higher in the troposphere. When a parcel of air moves upwards it expands. When air expands it cools. Due to this reason, the base of the troposphere is warmer than its base because the air in the surface of the Earth absorbs the sun’s energy, gets heated up and moves upward as a result of which it cools down.

Stratosphere

Above the troposphere lies the stratosphere which extends from the top of the troposphere to about 50 km (31 miles) above the ground. The ozone layer lies within the stratosphere. Ozone molecules in this layer absorb high-energy ultraviolet (UV) light from the Sun and convert it into heat. Because of this, unlike the troposphere, the stratosphere gets warmer the higher you go! 

Mesosphere

Above the stratosphere is the mesosphere and it extends to a height of about 85 km (53 miles) from the ground. Here, the temperature grows colder as you rise up through the mesosphere. The coldest parts of our atmosphere are located in this layer and can reach –90°C.

Thermosphere

Thermosphere lies above the mesosphere and this is a region where the temperature increases as you go higher up. The temperature increase is caused due to the absorption of energetic ultraviolet and X-Ray radiation from the sun. However, the air in this layer is so thin that it would feel freezing cold to us! Satellites orbit Earth within the thermosphere. Temperatures in the upper thermosphere can range from about 500° C to 2,000° C or higher. The aurora, the Northern Lights and Southern Lights, occur in the thermosphere.

Exosphere

Exosphere is the final frontier of the Earth’s gaseous envelope. The air in the exosphere is constantly but gradually leaking out of the Earth’s atmosphere into outer space. There is no clear cut upper boundary where the exosphere finally fades away into space. 

Ionosphere

The ionosphere isn’t a distinct layer unlike other layers in the atmosphere. The ionosphere is a series of regions in parts of the mesosphere and thermosphere where high-energy radiation from the Sun has knocked electrons loose from their parent atoms and molecules

 

Summary of Layers of Atmosphere

Region Altitude Range (km) Temperature Range(0oC) Important Characteristics
Troposphere 0-11 15 to -56 Weather occurs here
Stratosphere 11-50 -56 to -2 The ozone layer is present here
Mesosphere 50-85 -2 to -92 Meteors burn in this layer
Thermosphere 85-800 -92 to 1200 Aurora’s occur here

Watch this video to know everything about the air around us. Although, technically we call it the atmosphere – the circle of air. Learn how this atmosphere arranges itself in 4 layers above earth – troposphere, stratosphere, mesosphere, thermosphere, how the ozone layer protects us from the harmful UV rays of the sun, and why does it feel cold when we go up high in the air.


What would happen if the Earth’s Atmosphere disappeared?

Have you ever wondered what would happen if the Earth lost its atmosphere? Here is a breakdown of what could happen:

  • Birds and Planes would fall from the sky. Although we can’t see air, it has a mass that supports flying objects.
  • The sky would turn black. The sky gets its colour blue due to the atmosphere. Gases and particles in Earth’s atmosphere scatter sunlight in all directions. Blue light is scattered more than other colours because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.
  • There would be no sensation of sound. Although you could feel vibrations from the ground you wouldn’t hear anything. Sound requires a medium to travel.
  • All the water bodies such as rivers, lakes and oceans would boil away. Boiling occurs when the vapour pressure of a liquid exceeds external pressure. In a vacuum, the water readily boils.
  • Organisms that breathe air to survive would die. 

Composition of Atmosphere – Gases in the Atmosphere

The atmospheric composition of gas on Earth is largely conducted by the by-products of the life that it nurse.

Dry air from earth’s atmosphere contains 0.038% of carbon dioxide, 20.95% of oxygen, 78.08% of nitrogen and 0.93% of argon.

Traces of hydrogen, neon, helium, nitrous oxide, ozone and other “noble” gases, but generally a variable amount of water vapour is also present, on average about 1% at sea level.

Frequently Asked Questions – FAQ’s

What is the greenhouse effect?

The process of gases in the Earth’s atmosphere trapping the Sun’s heat is known as the greenhouse effect. Due to this process, the Earth is much warmer than it would be without an atmosphere. The greenhouse effect is one of the things that makes Earth a comfortable place to live.

Where does the Earth’s atmosphere end?

The earth’s atmosphere doesn’t end at a specific place. The higher we go, the thinner the atmosphere gets. There is no clear distinction between the atmosphere and outer space. 75% of the atmosphere is within 11 kilometres of the Earth’s surface.

Why do passenger jet planes and commercial aeroplanes prefer flying in the Stratosphere?

The jet planes fly in the lower stratosphere because of less turbulence in the stratosphere leading to a smooth ride. Planes usually flow near the border between the troposphere and the stratosphere.

Why do passenger jet planes and commercial aeroplanes prefer flying in the Stratosphere?

The jet planes fly in the lower stratosphere because of less turbulence in the stratosphere leading to a smooth ride. Planes usually flow near the border between the troposphere and the stratosphere.

Which layer of the atmosphere contains the ozone layer?

The stratosphere contains the ozone layer. The stratospheric ozone layer absorbs most of the sun’s ultraviolet light and thereby protects the earth.

Which instrument is used to measure the air pressure?

A barometer is used to measure air pressure.

Stay tuned to BYJU’S and FALL IN LOVE WITH LEARNING!

2 Comments

  1. Byju’s is always the best

Leave a Comment

Your email address will not be published. Required fields are marked *

BOOK

Free Class