Definition of Mesosphere
The mesosphere represents the third layer of Earth's atmosphere, residing above the stratosphere and underneath the thermosphere. It extends from approximately 50 to 85 kilometers (31 to 53 miles) above Earth's surface and is the region where most meteors undergo combustion upon entering the atmosphere.
Characteristics of the Mesosphere
Temperature: The mesosphere exhibits a unique attribute: temperatures diminish as altitude increases. The mesopause, the uppermost layer of the mesosphere, manifests the coldest temperatures in Earth's atmosphere, plummeting below -130 degrees Celsius (-202 degrees Fahrenheit).
Air Pressure: Despite the mesosphere's air pressure being significantly low compared to Earth's surface, it still possesses enough force to decelerate and heat meteoroids as they penetrate the atmosphere.
Composition: The mesosphere consists largely of nitrogen and oxygen but also houses small ice particles. Furthermore, it is the atmospheric layer where most meteors burn upon entering the atmosphere.
Phenomena in the Mesosphere
Meteors: The mesosphere earns the title of the "meteor layer" of the atmosphere due to it being the location where most meteors burn up owing to friction with atmospheric particles. The observed streak of light, or "shooting star", is the result of the heated air glowing as the meteor combusts.
Noctilucent Clouds: The highest clouds in Earth's atmosphere, known as noctilucent clouds, exist in the mesosphere. They can only be observed when sunlight, originating from below the horizon, illuminates them while the lower atmospheric layers and the Earth's surface are obscured by Earth's shadow.
Exploration and Study of the Mesosphere
The exploration of the mesosphere is limited due to its altitude: it is beyond the reach of aircraft and below the orbit of satellites. Thus, the investigation into this atmospheric layer primarily involves the use of ground-based radar, measurements obtained from rockets, and occasional data from space shuttles.