Mesosphere
Topic: Atmosphere: Composition, Structure and Elements of Weather · NCERT: Class 9, Ch 3 "Atmosphere and Climate"; Class 11, Ch 7 "Composition and Structure of Atmosphere"
Meaning
The mesosphere is the layer above the stratosphere, from about 50 km to 80 km. Here temperature falls again with height, down to about −100°C at 80 km, the coldest point in the atmosphere. Its upper boundary is called the mesopause. Most meteors burn up here. As they rush through the thin air, friction heats them until they glow and vanish. The highest clouds of all, noctilucent clouds, form near the mesopause in polar summer.
Example
A "shooting star" seen from a dark sky in rural Rajasthan is usually a small meteor burning up in the mesosphere. It burns away long before it can reach the ground.
Don't confuse with
- Stratosphere: in the stratosphere, temperature rises with height because of ozone. In the mesosphere, it falls with height.