CBSE Class 9 Geography Notes Chapter 4 Climate PDF Download

CBSE Class 9 Geography Notes Chapter 4 Climate: CBSE Class 9 Geography Notes Chapter 4 on Climate are important for understanding the Earth's weather patterns. These notes highlight the key difference between weather and climate, providing clarity on how they are measured and studied. The notes cover the main climatic zones of the world, including tropical, temperate and polar regions, detailing their distinct characteristics and locations on the planet.

CBSE Class 9 Geography Notes Chapter 4 Climate Overview

CBSE Class 9 Geography Notes Chapter 4 PDF

CBSE Class 9 Geography Notes Chapter 4 PDF

CBSE Notes Class 9 Geography Chapter 4 – Climate

Climate

• Winter: Characterized by cold temperatures and shorter days.
• Summer: Known for warm to hot temperatures and longer days.
• Rainy Season: Occurs when there is a significant increase in precipitation, often associated with monsoons or other weather patterns.

Climatic Controls

Factors Affecting India’s Climate

1. Latitude : India spans across various latitudes influenced by the Tropic of Cancer, resulting in a mix of tropical and subtropical climates.
2. Altitude : With mountains in the north and low coastal areas, India's elevation varies significantly. The northern mountains moderate winter temperatures compared to the plains.
3. Pressure and Winds : India's climate is shaped by:
   • Surface Winds : Monsoon winds originating from the southern Indian Ocean bring moisture-laden air towards the subcontinent, causing seasonal rainfall.
   • Upper Air Circulation : Jet streams, fast-flowing currents in the upper atmosphere, impact weather patterns.
4. Western Cyclonic Disturbances and Tropical Cyclones : These weather systems bring significant rainfall and influence regional weather patterns.

The Indian Monsoon

1. Seasonal Reversal of Winds : Monsoon refers to the seasonal reversal of wind direction. During summer, landmasses in India heat up more than surrounding oceans, creating low-pressure areas over land and high-pressure areas over the seas.
2. Inter-Tropical Convergence Zone (ITCZ) : The shift of the ITCZ over the Ganga plain during summer, known as the monsoon trough, brings heavy rainfall to the region.
3. High-Pressure Systems : A high-pressure area east of Madagascar and over the Indian Ocean affects the monsoon by influencing wind patterns.
4. Tibetan Plateau : Intense heating of the Tibetan Plateau creates low-pressure systems at high altitudes, contributing to the monsoon's strength.
5. Jet Streams : The movement of the westerly jet stream north of the Himalayas and the tropical easterly jet stream over the Indian peninsula during summer also play significant roles in the monsoon's behavior.
6. Southern Oscillation (SO) : Variations in pressure conditions over the southern oceans, coupled with irregular wind and sea surface temperature changes in the tropical eastern Pacific Ocean (known as Southern Oscillation), affect monsoon patterns in the tropics and subtropics.

The Onset of the Monsoon and Withdrawal

Duration and Timing : The monsoon typically lasts for about 100-120 days, starting from early June to mid-September. The arrival of the monsoon is marked by a sudden increase in rainfall, known as the "burst" of the monsoon.

Arrival in Different Regions :

• Southern India : The monsoon first reaches the southern tip of the Indian peninsula by the first week of June.
• Branches : It then splits into two branches - the Arabian Sea branch and the Bay of Bengal branch.
• Mumbai : The Arabian Sea branch reaches Mumbai around June 10th.
• Assam : The Bay of Bengal branch reaches Assam by the first week of June.
• Central India : By mid-June, the Arabian Sea branch extends over Saurashtra-Kuchchh and central India.
• Northwestern Plains : Both branches merge over the northwestern part of the Ganga plains.
• Delhi : Delhi receives monsoon showers from the Bay of Bengal branch by the end of June.
• Northern India : By the first week of July, western Uttar Pradesh, Punjab, Haryana, and eastern Rajasthan experience monsoon rains.
• Complete Coverage : By mid-July, the monsoon covers Himachal Pradesh and spreads across the rest of the country.

Withdrawal of the Monsoon

1. Start of Withdrawal : The monsoon begins to withdraw from the northwestern states of India by early September.
2. Northern Peninsula : By mid-October, the monsoon withdraws completely from the northern half of the peninsula.
3. Southward Progression : The withdrawal progresses southward:
   • North to South : From north to south, the withdrawal occurs between the first week of December to the first week of January.
   • Completion : By early December, the monsoon has withdrawn from the rest of the country.