Mesosphere
Introduction
The mesosphere is the third layer of the Earth's atmosphere, situated above the stratosphere and below the thermosphere. It extends from about 50 to 85 kilometers (31 to 53 miles) above our planet's surface. The mesosphere is primarily accessed by high-altitude balloons and sounding rockets, as it is above the maximum altitude for aircraft and below the minimum altitude for orbital spacecraft.
Characteristics
The mesosphere is characterized by temperatures that rapidly decrease as altitude increases. This is the opposite of the stratosphere, where temperature increases with altitude. The top of the mesosphere, known as the mesopause, is the coldest part of Earth's atmosphere, with temperatures averaging about -85 degrees Celsius (-121 degrees Fahrenheit).
The mesosphere is also where most meteoroids burn up upon entering the atmosphere due to the intense friction between the meteoroid and the atmospheric gases. This is often visible from Earth's surface in the form of a meteor shower.
Composition
The mesosphere, like other layers of the atmosphere, is composed primarily of nitrogen and oxygen. However, it also contains trace amounts of other gases such as carbon dioxide, water vapor, and noble gases like argon and neon. The presence of these gases can influence the temperature and density of the mesosphere.
Dynamics
The dynamics of the mesosphere are complex and not fully understood. It is known that atmospheric tides and planetary waves play a significant role in the mesosphere's behavior. These waves are generated in the lower atmosphere and propagate upwards, causing variations in the wind and temperature of the mesosphere.
In addition, the mesosphere exhibits a phenomenon known as "noctilucent clouds". These are the highest clouds in the Earth's atmosphere, located in the mesosphere's upper region. They are visible only during local summer months and when the Sun is below the observer's horizon, but while these very high clouds are still in sunlight.
Exploration and Research
The mesosphere is the least studied layer of the Earth's atmosphere due to its difficult accessibility. It is too high for aircraft and balloons to reach, and too low for satellites to orbit. However, scientists have been able to gather information about the mesosphere using sounding rockets, satellite remote sensing, and ground-based radar observations.
Research in the mesosphere is important for understanding global climate change, as changes in the mesosphere can indicate changes in the lower atmosphere. In addition, studying the mesosphere can help us understand other planets' atmospheres, as the conditions in the Earth's mesosphere are similar to those on Mars and other planets.