Mesopause, tropopause, and stratopause are the thermal transition areas that play an important role in the vertical coupling of the Earth's atmosphere. The mesopause is the temperature minimum point at the atmospheric boundary between the mesosphere and thermosphere. The thermosphere's temperature rises as it rises in altitude. In this article, you will read about the concept of mesopause which is important for the IAS exam.

Mesosphere

• Mesopause is the boundary between the Mesosphere and the Thermosphere at approximately 90km above the surface.
• For many years, the altitude of the mesopause was considered to be around 85 km, however, measurements at higher altitudes and modeling studies in the last decade have revealed that the mesopauseconsists of two minima, one at about 85 km and a stronger minimum at about 100 km.
• The mesosphere is the coldest zone on Earth, with temperatures as low as -100 °C due to a lack of solar energy and very significant radiative cooling from carbon dioxide.

Features of Mesopause

• Summer mesopause is also cooler than winter mesopause which is sometimes referred to as the mesopause anomaly.
• Upwelling at the summer pole and downwelling at the winter pole are the result of a summer-to-winter circulation.
• Rising air expands and cools, resulting in a chilly summer mesopause, while downwelling air compresses and warms, resulting in a warm winter mesopause.
• Gravitational-wave dissipation in the mesosphere deposits momentum against the mean east–west flow, resulting in a tiny north–south circulation.

Recent Context on Mesopause

• In recent years, investigations on global climate change linked to increases in CO2 have focused on the mesopause.
• In contrast to the troposphere, where more CO2 causes the atmosphere to warm, higher CO2 in the mesosphere causes the atmosphere to cool due to increased radiative emission.
• This has a demonstrable effect: as CO2 levels rise, the mesopause should grow cooler.
• The temperature of the mesopause does appear to be decreasing, albeit the magnitude of this decline varies and needs to be studied more. This phenomenon has also been the subject of modeling studies.

Conclusion

The temperature of the mesopause does appear to be decreasing, but the magnitude of this decline varies and needs to be studied more. As mesopause affects the radio propagation on Earth, it also has a practical significance.

FAQs

Question. What is the mesopause?

Question. What happens at the mesopause?

Question. How does the mesopause differ from other atmospheric boundaries?

Question. Why is the mesopause important in atmospheric science?

Question. How does the mesopause relate to space weather?

MCQs

1. What is the primary characteristic of the mesopause?

A) It is the warmest part of the atmosphere

B) It is the boundary between the thermosphere and the stratosphere

C) It is the coldest part of the Earth's atmosphere

D) It is located at the Earth's surface

2. At what altitude does the mesopause typically occur?

A) 10-20 km

B) 30-50 km

C) 50-85 km

D) 85-100 km

3. Which of the following layers is located directly below the mesopause?

A) Thermosphere

B) Stratosphere

C) Mesosphere

D) Troposphere

4. What happens to the temperature at the mesopause?

A) The temperature increases

B) The temperature remains constant

C) The temperature decreases and reaches its minimum

D) The temperature rises after a steady decline

5. Which of the following best describes the interaction of solar radiation at the mesopause?

A) Solar radiation has no impact at this altitude

B) It increases the temperature of the mesopause

C) It causes auroras and impacts ionization levels in the thermosphere

D) It leads to the formation of weather patterns

GS Mains Questions and Model Answers

Q1: Explain the role of the mesopause in the Earth's atmospheric structure.

Answer: The mesopause marks the boundary between the mesosphere and the thermosphere, making it a crucial point in understanding the Earth's atmospheric structure. It is the coldest part of the atmosphere, with temperatures plunging to as low as -90°C. The mesopause plays a key role in atmospheric dynamics, acting as the transition zone between the cooling mesosphere and the warming thermosphere. This boundary is significant in the study of atmospheric waves, meteorological phenomena, and space weather, as it is impacted by solar radiation and influences the ionization levels in the thermosphere. Understanding the mesopause is essential for comprehending the Earth's energy balance, climate patterns, and the interaction between the atmosphere and space.

Q2: Analyze the impact of solar radiation on the mesopause and the thermosphere.

Answer: Solar radiation has a profound effect on the mesopause and the thermosphere. The mesopause marks the region where the temperature reaches its lowest point, but above this layer, in the thermosphere, solar radiation causes a dramatic rise in temperature. This interaction plays a crucial role in the ionization processes of the thermosphere, where high-energy solar radiation ionizes the gases, creating the ionosphere. The energy received at the mesopause and thermosphere also contributes to space weather phenomena like auroras, which are visible when charged particles from the sun interact with the Earth's magnetosphere. These effects are essential in understanding space weather and its potential impact on satellite communications and technology.

Q3: Evaluate the significance of the mesopause in the study of atmospheric and space science.

Answer: The mesopause is a critical boundary layer in atmospheric and space science studies. As the coldest region of the Earth's atmosphere, it marks the transition between two contrasting temperature regimes: the cooler mesosphere and the warmer thermosphere. The study of the mesopause helps scientists understand the dynamics of the Earth's upper atmosphere, including the interaction of solar radiation with atmospheric gases. This region is also important in the study of atmospheric waves, meteorological phenomena, and the role of the ionosphere in space weather. The mesopause’s relationship with solar radiation, particularly its role in the formation of auroras, provides valuable insights into the behavior of charged particles and the Earth's magnetosphere.

Previous Year Questions on  Mesopause

1. UPSC CSE 2016

Question: "Discuss the role of the mesopause in the atmospheric structure and its significance in climate science."

Answer: The mesopause plays a significant role in the Earth's atmospheric structure as the boundary between the mesosphere and the thermosphere. It is crucial in the study of temperature profiles and atmospheric dynamics. Its cold temperatures are vital for understanding the behavior of atmospheric gases and their interaction with solar radiation. The mesopause also affects space weather, contributing to phenomena like auroras, and plays a role in understanding the Earth's energy balance and climate patterns.

2. UPSC CSE 2019

Question: "Analyze the importance of solar radiation in the formation of the thermosphere and its effects on the mesopause."

Answer: Solar radiation significantly impacts the formation of the thermosphere, where the temperature increases with altitude due to the absorption of high-energy solar radiation. This process leads to the ionization of atmospheric gases, creating the ionosphere. The mesopause, being the coldest part of the atmosphere, is directly affected by solar radiation, as the energy received influences the temperature distribution in the atmosphere and contributes to space weather phenomena, such as auroras, which are visible manifestations of