What is meant by the term mesosphere?

The term mesosphere refers specifically to a layer of Earth's atmosphere that is located above the stratosphere and below the thermosphere. This layer is significant because it is where the temperatures begin to decrease with altitude, making it distinct from the heated upper layers of the atmosphere. The mesosphere extends from about 50 to 85 kilometers above sea level and is characterized by its role in atmospheric phenomena, such as the burning up of meteoroids, which creates visible meteors.

Understanding the various atmospheric layers is crucial as each has different properties and functions. For instance, the troposphere is where weather occurs, while the stratosphere is known for the ozone layer that protects us from ultraviolet radiation. The mesosphere plays an essential role but is less discussed than these other layers, hence the need to classify it accurately. The other options describe different layers or areas that do not accurately fit the definition of the mesosphere.