Definition - What does Mesosphere mean?
The layer of the earth’s atmosphere above the stratosphere is known as the mesosphere. This atmospheric layer is found 50 to 85km above the surface of the earth and is characterized by temperatures that decrease with increasing height, resulting in temperatures as low as -130 F.
Safeopedia explains Mesosphere
The mesosphere is extremely difficult to study since it is much too high for aircraft, and satellites orbit above it. As a result, almost all measurements, with the exception of snapshots taken by sounding rockets, have been done indirectly. The thermosphere occurs above the mesosphere, and the point where the mesosphere transitions to thermosphere is known as the mesopause. At its lowest point, the dividing line between stratosphere and mesosphere is known as the stratopause.