Structure of the atmosphere
Also called: Layers of the atmosphere · Topic: Atmosphere: Composition, Structure and Elements of Weather · NCERT: Class 11, Ch 7 "Composition and Structure of Atmosphere"
Meaning
The atmosphere is divided into five layers based on how temperature changes with height. From the ground up, they are the troposphere, stratosphere, mesosphere, thermosphere and exosphere. Air is densest at the surface and gets thinner with height. Temperature falls with height only in the troposphere and mesosphere. It rises in the stratosphere, where ozone absorbs UV rays, and it rises again in the thermosphere. Thin boundary zones such as the tropopause and mesopause separate the layers.
Example
On a flight from Delhi to London, rain and storms are left behind in the troposphere below. The plane cruises at about 10–12 km, near the tropopause. Far above, the International Space Station orbits at about 400 km, in the thermosphere.
Don't confuse with
- Ionosphere: it is not a separate sixth layer. It is a zone of charged particles that lies inside the thermosphere, at about 80–400 km.