Layers of Atmosphere - Definition, Composition, Diagram, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:49 PM IST

The atmosphere is the layer of air that surrounds the Earth. It protects life, controls the weather, and keeps the planet warm. It is made of gases like nitrogen, oxygen, carbon dioxide, and others. An envelope of air surrounding the earth is known as the atmosphere. The atmosphere extends up to a distance of 32,000km. It is the most important part of our environment. The atmosphere is an essential part of our biosphere as its composition is responsible for changes in weather and climate on our planet and other life-supporting systems. Let's explore the Layers of Atmosphere in detail.

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Layers of the Atmosphere
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

Layers of Atmosphere - Definition, Composition, Diagram, FAQs

Layers of the Atmosphere

The structure of the atmosphere consists of five layers. Each layer has its characteristics. Let's discuss each layer in detail.

Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

Troposphere

It is the lowest layer of the atmosphere having 75% of the total weight of the atmosphere. It is 10 km thick at the poles and 18km thick at the equator. There is a 1°C temperature fall with a 165m increase in altitude. This is known as the normal lapse rate.

The term “Tropo” means change. Most of the weather phenomena take place in the troposphere such as dust, storm, rainfall, snowfall, etc. In this layer, we also see twilight, sunrise, sunset, and scattering of light. The troposphere is the hottest part of the atmosphere because it absorbs the highest amount of solar energy emitted by the rocks, mountains, and water on the earth.

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Stratosphere

Stratosphere is the second layer of the atmosphere, next to the troposphere. It extends up to 3km above the surface of the earth. It is a calm and clean sphere. The absence of water vapours prevents the formation of clouds, hence providing very clear visibility. This sphere is also free of air pocket, i.e., pilots prefer to fly in this sphere, we also see the formation of mother of pearl cloud or nacreous cloud.

The ozone layer is found in the stratosphere. It is around 15-30km above the earth. There is plenty of ozone gas in this sphere, Hence it is known as the ozonosphere. Ozonesphere is very useful because it absorbs the ultraviolet radiations of the sun and protects life on the earth. We cannot live up to five minutes if the ozone layer is destroyed.

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Mesosphere

It is the third layer next to the stratosphere. The mesosphere characteristics by low atmospheric pressure and low temperature. The temperature begins to drop from stratopause, goes on decreasing with the increase in height, and reaches a minimum of about -95℃ at a level of about 60km above the earth’s surface. At an 80-90 km altitude menopause separates the mesosphere from the thermosphere. But decreases in temperature in the mesosphere are due to some gas molecules present in the mesosphere that absorb the radiation of the sun hence, Mesosphere is the coldest layer of the atmosphere.

Why Mesosphere is the coldest layer of the atmosphere?

The mesosphere is the coldest layer of the atmosphere because the air is extremely high in this layer and it has little capacity for retaining heat. The heat transfers from surface to space at a much faster rate than it heats up by the Sun’s rays. Therefore, the temperatures here in this layer are normally as low as -90°C which is the lowest temperature for any atmospheric layer.

Thermosphere

It is the fourth layer next to the mesosphere. In this sphere due to the absorption of energetic ultraviolet and X-ray radiation from the sun temperature increases. The temperature of the thermosphere increases with height and it can rise as high as 1500 °C. It consists of a large part of the ionosphere. It extends about 80km above sea level. At an altitude range of 500–1000 km, thermopause separates the exosphere from the thermosphere. The thermosphere is the hottest layer of the atmosphere.

Why thermosphere is the hottest layer of the atmosphere?

This layer is the nearest to the Sun’s energy and hence it captures and absorbs heat most. As a result, most of the solar radiations that include X-ray and ultraviolet rays are present, and thus the thermosphere is the warmest layer of the atmosphere.

Ionosphere

The ionosphere is not a separate layer but a region within the thermosphere and partially in the mesosphere. It spans from about 50 km to 1,000 km above Earth's surface.

It extends from 60 to 500km. Due to the presence of ions - electrically charged particles it is called the ionosphere. It reflects radio waves back to the earth which helps in wireless communication. It also absorbs X-rays emitted from sun rays. In this sphere, temperature increases with height because of the radiation from the sun.

Exosphere

The exosphere is the outermost layer of the Earth's atmosphere. It provides space for interplanetary happenings. It ranges from 500 km to 1,000km above the earth. This part gradually merges with the outer spaces.

How to memorize seven layers of earth?

To remember all the layers of the atmosphere in ascending order from the earth’s surface to the space you can use the following mnemonic. Each word corresponds to a specific layer, starting from the lowest to the highest:

"The Smart Monkey Takes Exams."

T - Troposphere
S - Stratosphere
M - Mesosphere
T - Thermosphere
E- Exosphere

Frequently Asked Questions (FAQs)

1. Which layer of the atmosphere is the warmest?

The thermosphere is the warmest layer of atmosphere.

2. Ozone is found in which layer of atmosphere?

Ozone is found in the stratosphere.

3. How many layers are there in the atmosphere OR how many spheres are in atmosphere and what is the order of layers in the atmosphere?

There are five layers in the atmosphere.

Order of layers of atmosphere in the atmosphere is, troposphere stratosphere mesosphere thermosphere exosphere.

4. What is the hottest layer of the atmosphere?

The thermosphere is the hottest layer of the atmosphere.

5. Why is the mesosphere cold?

There are some gas molecules are present in this layer that absorbs the solar radiation so the mesosphere is the coldest layer of the atmosphere.

6. What are the 4 layers of the atmosphere?

The four important layers of the atmosphere are, troposphere stratosphere mesosphere thermosphere.

7. How does air pressure change as you move up through the atmosphere?

Air pressure decreases as you move up through the atmosphere. This is because there are fewer air molecules at higher altitudes, resulting in less weight of air pressing down. This principle explains why it's harder to breathe at high elevations and why airplanes need pressurized cabins.

8. What is the Kármán line and why is it significant?

The Kármán line, located at an altitude of about 100 km, is the commonly accepted boundary between Earth's atmosphere and outer space. It's significant because it marks the point where atmospheric effects become negligible for aircraft, and orbital dynamics start to dominate for spacecraft.

9. How does the composition of the atmosphere change with altitude?

The composition of the atmosphere changes with altitude. Near the Earth's surface, the air is mostly nitrogen (78%) and oxygen (21%), with small amounts of other gases. As you go higher, the proportion of lighter gases like hydrogen and helium increases, while heavier gases become less abundant.

10. What causes the different colors in auroras?

The different colors in auroras are caused by charged particles from the sun colliding with various gases in the thermosphere and upper mesosphere. Oxygen produces green and red colors, while nitrogen creates blue and purple hues. The altitude of these collisions and the energy of the particles determine the specific colors observed.

11. How do atmospheric layers affect the spread of sound waves?

Atmospheric layers affect sound wave propagation primarily in the troposphere. Temperature inversions and wind shear can bend sound waves, causing them to travel further than expected. The stratosphere and higher layers have little effect on everyday sounds but can influence the propagation of very low-frequency sounds over long distances.

12. What are the main layers of Earth's atmosphere?

Earth's atmosphere consists of five main layers: troposphere (closest to Earth's surface), stratosphere, mesosphere, thermosphere, and exosphere (outermost layer). Each layer has distinct characteristics and plays a unique role in our planet's climate and protection.

13. Why is the troposphere warmer near the ground and cooler at higher altitudes?

The troposphere is warmer near the ground because the Earth's surface absorbs solar radiation and heats the air above it. As you go higher, the air becomes less dense and has fewer molecules to absorb and retain heat, resulting in cooler temperatures at higher altitudes.

14. How does the ozone layer protect life on Earth?

The ozone layer, located in the stratosphere, protects life on Earth by absorbing harmful ultraviolet (UV) radiation from the sun. It acts as a shield, preventing most of the sun's UV-B and UV-C rays from reaching the Earth's surface, which can cause skin cancer, eye damage, and harm to plants and animals.

15. What causes the aurora borealis (Northern Lights) and where does it occur?

The aurora borealis occurs in the thermosphere and is caused by charged particles from the sun colliding with gas molecules in Earth's upper atmosphere. These collisions excite the molecules, causing them to emit light. The phenomenon is typically visible near the Earth's magnetic poles.

16. Why do meteors burn up in the mesosphere?

Meteors burn up in the mesosphere because as they enter Earth's atmosphere at high speeds, they encounter increasing air resistance. This friction causes the meteor to heat up and vaporize, creating the bright streaks we see as "shooting stars" in the night sky.

17. What role does the exosphere play in Earth's atmosphere?

The exosphere is the outermost layer of Earth's atmosphere, extending from about 700 km to 10,000 km above the Earth's surface. It plays a crucial role in protecting Earth from solar wind and cosmic radiation. It also contains satellites and is where many space phenomena occur.

18. Why is the stratosphere important for air travel?

The stratosphere is important for air travel because it offers stable conditions for flying. Unlike the turbulent troposphere below, the stratosphere has minimal vertical air movement and relatively constant temperatures. This stability allows commercial aircraft to fly more smoothly and efficiently.

19. How does the greenhouse effect relate to the atmosphere's layers?

The greenhouse effect primarily occurs in the troposphere and lower stratosphere. Greenhouse gases like carbon dioxide and water vapor trap heat from the Earth's surface, warming the lower atmosphere. This natural process is essential for maintaining Earth's habitable temperature, but human activities are enhancing it, leading to global warming.

20. What causes the temperature inversion in the stratosphere?

The temperature inversion in the stratosphere (where temperature increases with altitude) is caused by the ozone layer. Ozone molecules in this layer absorb ultraviolet radiation from the sun, converting it into heat. This process warms the stratosphere from the top down, creating the inversion.

21. How do atmospheric layers affect radio communication?

The ionosphere, a region in the thermosphere, plays a crucial role in radio communication. It contains electrically charged particles that can reflect radio waves back to Earth, allowing long-distance communication. Different layers of the ionosphere reflect different frequencies, affecting various types of radio transmissions.

22. Why is the mesosphere the coldest layer of the atmosphere?

The mesosphere is the coldest layer because it's too high to be warmed by Earth's surface heat and too low to be heated by the sun's UV radiation (which is mostly absorbed in the stratosphere). Additionally, greenhouse gases in this layer radiate heat into space, further cooling it.

23. How do atmospheric layers influence weather patterns?

Weather patterns are primarily influenced by the troposphere, the lowest layer of the atmosphere. This is where most clouds form, precipitation occurs, and wind patterns develop. The interaction between the troposphere and stratosphere can also affect large-scale weather systems and climate patterns.

24. How do atmospheric layers protect Earth from solar radiation?

Different atmospheric layers protect Earth from solar radiation in various ways. The ozone layer in the stratosphere absorbs harmful UV radiation. The thermosphere absorbs X-rays and extreme UV radiation. The atmosphere as a whole scatters and reflects some incoming solar radiation, helping to regulate Earth's temperature.

25. Why does the air glow in the thermosphere?

The air in the thermosphere glows due to a process called airglow. This occurs when atoms and molecules in the upper atmosphere are excited by solar radiation during the day. At night, these particles release this energy as visible light, creating a faint, continuous glow in the sky.

26. How do atmospheric layers affect satellite orbits?

Atmospheric layers, particularly the thermosphere and exosphere, affect satellite orbits through atmospheric drag. Even though these upper layers are very thin, they can cause satellites in low Earth orbit to slow down over time, requiring periodic boosts to maintain their orbits. Higher layers have less effect on satellites in higher orbits.

27. What causes the formation of noctilucent clouds in the mesosphere?

Noctilucent clouds form in the mesosphere, near the mesopause (the boundary between the mesosphere and thermosphere). They are composed of ice crystals that form on dust particles at extremely low temperatures. These clouds are visible from Earth only when illuminated by sunlight from below the horizon, creating a striking blue-white appearance.

28. How do atmospheric layers influence the dispersion of pollutants?

Atmospheric layers influence pollutant dispersion primarily through temperature inversions and wind patterns. In the troposphere, temperature inversions can trap pollutants near the ground. The stratosphere's stability prevents most pollutants from rising higher, while upper layers like the mesosphere and thermosphere have minimal impact on ground-level pollution.

29. Why is the exosphere considered the edge of space?

The exosphere is considered the edge of space because it's the outermost layer of Earth's atmosphere, where the atmosphere gradually thins out into the vacuum of space. In this layer, gas molecules are so sparse that they rarely collide with each other and can escape Earth's gravity, blending into interplanetary space.

30. How do atmospheric layers affect the color of the sky?

The color of the sky is primarily affected by the troposphere and stratosphere. During the day, molecules in these layers scatter sunlight, with blue light scattered more than other colors, giving the sky its blue appearance. At sunset and sunrise, light travels through more atmosphere, scattering blue light and allowing red and orange to dominate.

31. What role does the ionosphere play in Earth's magnetic field?

The ionosphere, a part of the thermosphere, interacts with Earth's magnetic field to create complex electrical currents. These currents contribute to the overall structure of Earth's magnetosphere, which protects us from solar wind. The ionosphere also reflects and refracts radio waves, enabling long-distance communication.

32. Why is the mesopause the boundary between the mesosphere and thermosphere?

The mesopause is the boundary between the mesosphere and thermosphere because it marks a dramatic shift in temperature trends. It's the coldest part of Earth's atmosphere, with temperatures as low as -100°C. Above the mesopause, in the thermosphere, temperatures begin to rise rapidly due to the absorption of solar radiation.

33. How do atmospheric layers influence the formation and behavior of jet streams?

Jet streams primarily form in the upper troposphere and lower stratosphere. They are influenced by the temperature differences between these layers and the Earth's rotation. The stability of the stratosphere helps maintain jet streams, while the more turbulent troposphere can cause variations in their paths and strengths.

34. How do atmospheric layers affect the trajectory of space shuttles during re-entry?

During re-entry, space shuttles interact with multiple atmospheric layers. They first encounter the thin exosphere and thermosphere, where they begin to slow down. As they descend into the mesosphere and stratosphere, increasing air density causes significant heating. The shuttle's trajectory must be carefully controlled to manage this heat and safely navigate through the troposphere for landing.

35. Why is the homosphere different from the heterosphere?

The homosphere (including the troposphere, stratosphere, and mesosphere) is characterized by a relatively constant mix of atmospheric gases due to turbulent mixing. In contrast, the heterosphere (thermosphere and exosphere) has a composition that varies with altitude, with lighter gases becoming more prevalent at higher altitudes due to gravitational separation.

36. How do atmospheric layers affect the formation and dissipation of the ozone hole?

The ozone hole primarily forms in the stratosphere over polar regions. It's caused by the destruction of ozone molecules by chlorofluorocarbons (CFCs) and other pollutants. The stable nature of the stratosphere allows these chemicals to accumulate, while the extreme cold in polar stratospheric clouds enhances ozone depletion. The hole's size is influenced by stratospheric winds and temperature patterns.

37. What is the role of the tropopause in weather and climate?

The tropopause, the boundary between the troposphere and stratosphere, plays a crucial role in weather and climate. It acts as a "lid" on the troposphere, influencing the vertical development of storms and the distribution of water vapor. Changes in the height of the tropopause can indicate shifts in global climate patterns.

38. How do atmospheric layers affect the propagation of gravity waves?

Gravity waves, oscillations in the atmosphere caused by buoyancy forces, can propagate through multiple atmospheric layers. They often originate in the troposphere and can travel upwards through the stratosphere and mesosphere. These waves play a role in transferring energy and momentum between atmospheric layers, influencing global circulation patterns.

39. Why does the composition of the thermosphere change during solar storms?

During solar storms, the increased influx of high-energy particles and radiation causes more ionization in the thermosphere. This can alter its composition by breaking apart molecules and creating new ions. The heating of the thermosphere during these events also causes it to expand, changing the relative concentrations of gases at different altitudes.

40. How do atmospheric layers influence the formation of sprites and other upper-atmospheric electrical phenomena?

Sprites and other upper-atmospheric electrical phenomena typically occur in the mesosphere and lower ionosphere. They are triggered by powerful lightning strikes in the troposphere, which create electromagnetic pulses that propagate upwards. The varying electrical properties and ion concentrations in different atmospheric layers influence the formation and appearance of these phenomena.

41. What is the significance of the turbopause in atmospheric studies?

The turbopause, located at the top of the homosphere (around 100 km altitude), marks the transition between turbulent mixing and molecular diffusion. Below this level, gases are well-mixed; above it, gases separate based on molecular weight. Understanding the turbopause is crucial for studying atmospheric composition, dynamics, and the transition to space.

42. How do atmospheric layers affect the distribution of cosmic rays?

Cosmic rays interact with all atmospheric layers, but their effects vary with altitude. The upper layers (thermosphere and mesosphere) experience the initial impact of high-energy cosmic particles. As these particles penetrate deeper, they interact with atmospheric molecules, creating cascades of secondary particles. The dense lower atmosphere (troposphere and stratosphere) provides the most shielding for Earth's surface.

43. Why is the F-layer of the ionosphere important for long-distance radio communication?

The F-layer, located in the thermosphere, is the most important layer for long-distance radio communication because it contains the highest concentration of ions. This layer can reflect radio waves back to Earth, allowing signals to travel great distances by bouncing between the Earth and the ionosphere. The F-layer's height and electron density vary with solar activity, affecting radio propagation.

44. How do atmospheric layers influence the formation and behavior of polar vortices?

Polar vortices primarily form in the stratosphere during winter months. The temperature gradient between the dark polar regions and the sunlit mid-latitudes creates strong circumpolar winds. The stability of the stratosphere allows these vortices to persist, while interactions with the troposphere can lead to their weakening or breakdown, potentially influencing weather patterns at the surface.

45. What causes the airglow phenomenon in different atmospheric layers?

Airglow occurs in multiple atmospheric layers, primarily the mesosphere and lower thermosphere. It's caused by various chemical reactions and excitation of atmospheric atoms and molecules by solar radiation. Different colors of airglow are associated with specific reactions: green from oxygen atoms in the mesosphere, red from oxygen in the thermosphere, and infrared from hydroxyl radicals.

46. How do atmospheric layers affect the dispersion of volcanic ash?

Volcanic ash dispersion is primarily affected by the troposphere and lower stratosphere. In the troposphere, ash is subject to weather patterns and can be quickly dispersed or washed out by precipitation. If ash reaches the stratosphere, it can remain suspended for longer periods due to the layer's stability, potentially affecting global climate and aviation over wider areas.

47. Why is the mesosphere important for studying climate change?

The mesosphere is important for climate change studies because it's highly sensitive to changes in atmospheric composition and temperature. Phenomena like noctilucent clouds in the mesosphere can serve as indicators of long-term climate trends. Additionally, changes in the mesosphere can influence lower atmospheric layers, potentially impacting weather and climate patterns.

48. How do atmospheric layers affect the behavior of high-altitude balloons?

High-altitude balloons are affected differently by each atmospheric layer they pass through. In the troposphere, they encounter varying winds and temperatures. The stable stratosphere allows for smoother flight, while the cold mesosphere can cause balloon materials to become brittle. The thermosphere's low density limits the maximum altitude these balloons can reach.

49. What is the role of the D-layer in radio wave absorption?

The D-layer, the lowest part of the ionosphere located in the mesosphere, plays a crucial role in absorbing medium and high-frequency radio waves during daylight hours. This absorption can disrupt long-distance radio communications. At night, the D-layer largely disappears, allowing radio waves to reach higher, more reflective layers of the ionosphere.

50. How do atmospheric layers influence the formation and persistence of the polar night jet?

The polar night jet forms in the stratosphere during winter months in polar regions. The extreme temperature difference between the dark pole and the sunlit mid-latitudes creates this strong circumpolar wind. The stratosphere's stability allows the jet to persist, while its interactions with the troposphere can influence surface weather patterns, including the position of the jet stream.

51. Why is the thermosphere's temperature so variable?

The thermosphere's temperature is highly variable because it's strongly influenced by solar activity. During periods of high solar activity, the thermosphere absorbs more solar radiation, causing temperatures to rise dramatically (up to 2000°C or more). Conversely, during low solar activity or at night, temperatures can drop significantly. Despite these high temperatures, the air feels cold due to its extremely low density.

52. How do atmospheric layers affect the propagation of infrasound waves?

Infrasound waves can travel long distances through atmospheric layers due to their low frequency. They are affected by temperature gradients and wind patterns in the troposphere and stratosphere. The thermosphere can act as a reflector for certain infrasound frequencies, allowing them to propagate globally. This property makes infrasound useful for detecting distant events like explosions or volcanic eruptions.

53. What causes the formation of polar stratospheric clouds and why are they significant?

Polar stratospheric clouds form in the winter polar stratosphere when temperatures drop extremely low. They are significant because they provide surfaces for chemical reactions that lead to ozone depletion. These clouds play a crucial role in the formation of the ozone hole, as they enable chlorine