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Indian Geography›Ch 1: Earth & Universe›Atmosphere and its Layers
Master atmospheric composition, thermal layers, and pressure belts for competitive exams.
Earth's atmosphere is structured into five distinct thermal layers based on temperature variation, with nitrogen and oxygen dominating its composition while pressure belts regulate global wind systems.
Memory Hooks
| Layer | Height Range | Key Feature |
|---|---|---|
| Troposphere | 0-12 km | Weather phenomena |
| Stratosphere | 12-50 km | Ozone layer & Jets |
| Mesosphere | 50-80 km | Coldest; Meteors burn |
| Thermosphere | 80-400 km | Ionosphere & Aurora |
Nitrogen 78%
(Most abundant gas)
Most abundant gas
Nitrogen dilutes oxygen and prevents rapid combustion.
Ozone O3
(UV ray shield)
UV ray shield
Found mainly in the stratosphere, blocking harmful UV rays.
Ionosphere
(Radio reflection)
Radio reflection
Enables long-distance wireless radio communication on Earth.
Exosphere
(Fades into space)
Fades into space
Outer limit where light gases like hydrogen escape to space.
Ozone layer is in troposphereOzone layer is in stratosphere
Bad ozone is at ground level, but the protective ozone shield resides in the stratosphere.
Temperature increases with height everywhereTemperature drops in troposphere
In the troposphere, temperature decreases with height at normal lapse rate.
Meteors burn in thermosphereMeteors burn in mesosphere
Mesosphere has adequate air density to cause friction and burn incoming meteors.
Q1.Which atmospheric layer contains the ozone layer responsible for absorbing harmful UV radiation?
Q2.Radio waves transmitted from Earth are reflected back by which layer?