Atmosphere – Temperature, Pressure and Wind System
This section explains the fundamental processes that control weather and climate: temperature variation, pressure belts, and wind systems. These concepts are highly important for UPSC and other competitive exams.
1. Temperature Distribution
Temperature in the atmosphere varies due to factors such as latitude, altitude, distance from sea, and seasonal changes.
- Equatorial regions receive maximum solar energy
- Temperature decreases with altitude in the troposphere
- Land heats and cools faster than water
Key Concept: Normal lapse rate → temperature decreases by ~6.5°C per 1000 meters
2. Atmospheric Pressure
Atmospheric pressure is the force exerted by the weight of air on the Earth’s surface.
- High pressure → cold, dense air
- Low pressure → warm, rising air
- Pressure decreases with altitude
3. Pressure Belts of the Earth
- Equatorial Low Pressure Belt (0°)
- Subtropical High Pressure Belts (30°)
- Subpolar Low Pressure Belts (60°)
- Polar High Pressure Belts (90°)
Importance: These belts control global wind systems and climate patterns
4. Wind System
Wind is the horizontal movement of air from high pressure to low pressure areas.
- Trade Winds: Blow from subtropical high to equatorial low
- Westerlies: Blow from west to east in mid-latitudes
- Polar Winds: Cold winds from polar regions
5. Jet Streams
Jet streams are fast-flowing air currents in the upper atmosphere.
- Located in the upper troposphere
- Influence weather patterns and monsoons
6. Coriolis Effect
Due to Earth’s rotation, winds are deflected:
- Right direction in Northern Hemisphere
- Left direction in Southern Hemisphere
Exam Focus Points
- Lapse rate → 6.5°C per km
- Wind = high pressure → low pressure
- Jet streams influence climate
- Coriolis effect causes wind deflection
Conclusion
Temperature, pressure, and wind systems together control the Earth’s weather and climate. Understanding these concepts helps in analyzing global climatic conditions and environmental changes.
Geography | Climate | Advanced Concepts
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