UPSC Prelims Special – Geography Synopsis | English | Page 2

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1. Atmosphere and Its Structure

The atmosphere is a layer of gases surrounding the Earth. It protects life on Earth and regulates climate and weather systems.

Major Layers of the Atmosphere

• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
• Exosphere

Weather phenomena mainly occur in the Troposphere.

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2. Temperature and Heat Zones

Temperature on Earth varies according to latitude, altitude, distance from the sea, and prevailing winds.

Heat Zones of the Earth

• Torrid Zone
• Temperate Zone
• Frigid Zone

Important Concepts

• Latitude influences temperature distribution
• Altitude decreases temperature
• Continentality affects climate

The Equator receives maximum solar energy.

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3. Winds and Pressure Belts

Winds are horizontal movements of air caused by differences in atmospheric pressure.

Major Pressure Belts

• Equatorial Low Pressure Belt
• Subtropical High Pressure Belt
• Subpolar Low Pressure Belt
• Polar High Pressure Belt

Types of Winds

• Trade Winds
• Westerlies
• Polar Easterlies

Trade Winds are important for tropical climate systems.

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4. Humidity, Clouds and Rainfall

Humidity refers to the amount of water vapor in the atmosphere. Cloud formation and rainfall are important parts of the hydrological cycle.

Types of Rainfall

• Convectional Rainfall
• Orographic Rainfall
• Cyclonic Rainfall

The Western Ghats receive heavy orographic rainfall.

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5. Cyclones and Anticyclones

Cyclones are low-pressure systems associated with strong winds and rainfall, while anticyclones are high-pressure systems with calm weather conditions.

Characteristics of Cyclones

• Low-pressure center
• Strong winds
• Heavy rainfall
• Storm surges in coastal regions

Tropical cyclones commonly form over warm ocean waters.

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Quick Revision Points

• Troposphere – Weather layer
• Equator receives maximum heat
• Trade Winds – Tropical winds
• Orographic Rainfall – Mountain rainfall
• Cyclones – Low-pressure systems

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Practice MCQ

Which layer of the atmosphere contains the ozone layer?

• A) Troposphere
• B) Mesosphere
• C) Stratosphere
• D) Thermosphere

Correct Answer: C) Stratosphere

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