The mesosphere is the third layer in sequence from the earth's surface to Earth's atmosphere after the troposphere and stratosphere. It extends from about 50 to 85 km (31 to 53 miles) above the Earth's Surface. Temperature decreases with height throughout the mesosphere. In this article, you will read about the mesosphere in detail for the IAS exam.

Mesosphere

• The mesosphere begins at the top of the stratosphere (also known as the stratopause) and ends at the mesopause.
• The coldest section of the Earth's atmosphere with temperatures below 143°C (225°F; 130 K).
• The exact upper and lower boundaries of the mesosphere vary with latitude and season (higher in winter and at the tropics, lower in summer and at the poles), but the lower boundary is usually around 50 to 65 km (31 to 40 mi; 164,000 to 213,000 ft) above the Earth's surface, and the upper boundary (the mesopause) is usually around 85 to 100 km (53 to 62 mi; 279,000 to 328,000 ft).
• The mesosphere is an intermediate layer beyond the ozone layer and continues up to an altitude of 80 km from the earth’s surface.
• Meteors or falling stars occur in this layer.
• The mesosphere has sometimes jocularly been referred to as the "ignorosphere" because it had been probably the least studied of the atmospheric layers.
• The stratosphere and mesosphere together are sometimes referred to as the middle atmosphere.

Temperature stratification in Mesosphere

• In the mesosphere temperature tends to drop with increased altitude, the mesopause separates the mesosphere from the thermosphere where temperature increases with increasing height until they approach 17000C.
• Temperatures decrease with height because heating by ultraviolet absorption by ozone falls off and, importantly, traces of carbon dioxide have a significant cooling effect.
• Mesopause has the lowest temperature. A temperature minimum of -90°C and lower is reached at 85 km at the mesopause.
• CO2 operates as a "greenhouse gas" in the lower atmosphere by absorbing infrared light emitted by the earth's surface. CO2 actually cools the atmosphere in the rarefied mesosphere by reflecting heat into space.

Features of the Mesosphere

• Since the mesosphere is more difficult to investigate than other layers of the atmosphere, as a result of this we have less information on it. Much about the mesosphere remains a mystery due to the difficulty of directly measuring it using devices.
• The mesosphere is not accessible by weather balloons or other aircraft.
• Satellites that orbit above the mesosphere are unable to see the characteristics of this layer directly.
• In the mesosphere, most meteors burn up. Because some meteoric material persists in the mesosphere, the concentration of iron and other metal atoms in this layer is relatively high.

Significance of Mesosphere

• In the mesosphere near the poles, peculiar high-altitude clouds known as "noctilucent clouds" or "polar mesospheric clouds" formed.
• These unusual clouds form significantly higher in the atmosphere than regular forms of clouds.
• The mesosphere is considerably drier than the humid troposphere, therefore cloud formation in this layer is unusual.
• Strange electrical discharges like lightning, known as "sprites" and "ELVES," emerge several kilometers (miles) above thunderclouds in the troposphere below.

Influence of waves and tides in the Mesosphere

• The mesosphere is influenced by various types of waves and tides in the atmosphere. These waves and tides transport energy from the troposphere and stratosphere into the mesosphere, where it drives the majority of the world's circulation.

Conclusion

There is a layer of Earth's atmosphere known as the mesosphere. Located directly above the stratosphere and below the thermosphere, it is known as the mesosphere. ' It rises to a height of 85 kilometres (31 miles) above Earth's surface. To describe the mesosphere, scientists have dubbed it "ignorosphere" because it is understudied compared to the stratospheric and thermospheric regions (in which satellites can orbit).

FAQs

Question. What is the mesosphere?

Question. What are the key features of the mesosphere?

Question. How does the mesosphere affect weather patterns?

Question. What causes the temperature drop in the mesosphere?

Question. How does the mesosphere compare to other layers of the atmosphere?

MCQs

1. Which of the following is true about the mesosphere?

A) It contains the ozone layer

B) Temperature decreases with altitude

C) It is the hottest part of the atmosphere

D) It is where most of the weather phenomena occur

2. What is the primary role of the mesosphere?

A) It is where most of the weather phenomena occur

B) It absorbs ultraviolet radiation

C) It protects Earth from meteoroids by causing them to burn up

D) It contains the highest concentration of ozone

3. What is the temperature range in the mesosphere?

A) -50°C to -90°C

B) 0°C to -50°C

C) -90°C to -140°C

D) 0°C to 50°C

4. What is the main characteristic of air in the mesosphere?

A) High density and high pressure

B) Low density and low pressure

C) High density and low pressure

D) Low density and high pressure

5. What happens to meteors when they enter the mesosphere?

A) They continue moving towards Earth's surface

B) They burn up due to friction with the atmosphere

C) They enter the thermosphere

D) They freeze and fall as ice particles

GS Mains Questions and Model Answers

Q1: Discuss the characteristics and role of the mesosphere in the Earth's atmospheric system.

Answer: The mesosphere is the third layer of Earth's atmosphere, extending from 50 km to 85 km above the Earth's surface. It is characterized by extremely low air pressure and temperature that decreases with altitude, reaching as low as -90°C. The mesosphere plays a vital role in protecting the Earth from the impact of meteoroids. As these meteoroids enter the atmosphere, they burn up due to friction with the air, which prevents them from reaching the Earth's surface. The mesosphere also plays a secondary role in the global climate system by acting as a buffer zone between the lower layers, such as the troposphere and stratosphere, and the thermosphere. Although it is not involved in weather formation, the mesosphere is critical in regulating the temperature structure of the upper atmosphere and protecting the planet from space debris.

Q2: Evaluate the importance of the mesosphere in the Earth's atmospheric processes.

Answer: The mesosphere is crucial in the Earth’s atmospheric processes despite its limited role in weather systems. Its importance lies in its ability to:

• Protect Earth from meteoroids: The mesosphere causes meteoroids to burn up due to the high friction encountered in this layer, preventing them from reaching Earth’s surface.
• Maintain atmospheric stability: The mesosphere acts as a transition zone between the stratosphere and thermosphere, ensuring the appropriate distribution of temperature and preventing sudden temperature fluctuations in the upper atmosphere.
• Contribute to heat dissipation: The cold temperatures in the mesosphere help dissipate heat from the lower layers of the atmosphere, contributing to the overall balance in Earth's thermal structure. Despite not directly influencing weather, the mesosphere plays a critical role in maintaining the integrity and protection of the Earth’s atmosphere.

Q3: What are the effects of temperature variations in the mesosphere on atmospheric dynamics?

Answer: Temperature variations in the mesosphere significantly affect atmospheric dynamics, as the layer has a highly complex interaction with both the thermosphere and the stratosphere:

• Thermal Gradient: The mesosphere is marked by a temperature decrease with altitude, creating a thermal gradient between it and the warmer stratosphere below and the thermosphere above. This gradient helps regulate atmospheric circulation patterns.
• Boundary with the Thermosphere: The transition from the cold mesosphere to the hot thermosphere causes the formation of the mesopause, the coldest part of Earth's atmosphere, where the behavior of atmospheric gases changes dramatically.
• Influence on Meteorological Phenomena: The temperature profile in the mesosphere can affect meteorological phenomena such as polar mesospheric clouds (PMCs), which are seen as an indication of the mesosphere's complex interaction with seasonal and climate variations.

Previous Year Questions on Mesosphere

1. UPSC CSE 2020

Question: "Explain the significance of the mesosphere in Earth's atmospheric system and its impact on weather patterns."

Answer: The mesosphere plays an important role in Earth’s atmospheric system by providing a transition between the stratosphere and thermosphere. While it does not directly influence weather patterns, it is essential for maintaining atmospheric stability. The mesosphere is responsible for the burning up of meteoroids, preventing them from impacting Earth's surface. Furthermore, the temperature gradient within the mesosphere contributes to thermal regulation between different layers of the atmosphere, affecting global climate systems and atmospheric dynamics.

2. UPSC CSE 2019

Question: "Describe the role of the mesosphere in protecting Earth from space debris and its importance in the atmospheric structure."

Answer: The mesosphere plays a crucial role in protecting Earth from space debris, primarily through the burning up of meteoroids. As meteoroids enter the mesosphere, the friction from the dense air causes them to disintegrate, preventing them from reaching the surface. This protective function is vital for Earth’s safety from space impacts. The mesosphere also contributes to the overall thermal structure of the Earth’s atmosphere, acting as a buffer zone between the more volatile layers above and below it, thus maintaining atmospheric balance and stability.