Why this matters now
Atmospheric structure and global wind systems are tested directly and underpin the monsoon, cyclones and climate. Jet streams and the ozone layer are common Prelims points.
Layers of the atmosphere
| Layer | Feature |
|---|---|
| Troposphere | Weather occurs here; temperature falls with height |
| Stratosphere | Contains the ozone layer (absorbs UV); calm — used by aircraft |
| Mesosphere | Coldest layer; meteors burn up |
| Thermosphere (Ionosphere) | Very hot; reflects radio waves; auroras |
| Exosphere | Outermost, merges with space |
Pressure belts
Global pressure is organised into belts: the equatorial low (ITCZ/doldrums), the subtropical highs (~30°), the subpolar lows (~60°) and the polar highs. These belts shift seasonally with the Sun and drive the planetary winds.
Planetary winds and jet streams
Planetary (prevailing) winds blow from high to low pressure, deflected by the Coriolis force: the trade winds (subtropical highs → equator), the westerlies (highs → subpolar lows) and the polar easterlies. High in the troposphere, fast, narrow jet streams (e.g. the subtropical westerly and tropical easterly jets) strongly influence weather and the monsoon.
Local and seasonal winds
Local winds arise from local pressure/temperature differences — e.g. land and sea breezes, mountain and valley breezes, and named winds like the Loo (hot summer wind of north India), Chinook and Mistral.
UPSC angle
Order the layers (and the ozone-in-stratosphere fact), the pressure belts, the three planetary wind systems and jet streams, plus named local winds (Loo). The Coriolis effect explains deflection.
Frequently asked questions
What are the layers of the atmosphere?
Troposphere, stratosphere, mesosphere, thermosphere (ionosphere) and exosphere.
Which layer contains the ozone layer?
The stratosphere, where ozone absorbs harmful ultraviolet radiation.
What are the planetary winds?
The permanent prevailing winds — trade winds, westerlies and polar easterlies — driven by the global pressure belts.
What is a jet stream?
A fast, narrow band of wind high in the troposphere that strongly influences weather systems and the monsoon.