Class 9 Geography Chapter 4 Notes - Climate

Important Points To Remember

1. Mango showers

• Pre-monsoon showers occurring in Kerala and coastal Karnataka.
• Help in the early ripening of mangoes.

Regions of Mango Shower and Kal Baisakh

2. Kalbaisakhi

• Means violent black clouds in the month of Baisakh.
• Refers to north-westerly and northerly winds in Bengal and Assam.
• Causes heavy rainfall and destruction.

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3. Chennai receives more rain in winter

4. Break or burst of the monsoon

• Sudden arrival of moisture-laden winds with violent thunder and lightning.
• Known as the "break" or "burst" of the monsoon.
• The first break occurs on the southwest coast of India around June 1st.

5. Southern Oscillation

• It is the interrelation between the pressure systems of the Pacific and Indian Oceans.
• When pressure is high in the Pacific, it is low in the Indian Ocean, and vice versa.
• Winds shift across the equator with seasons, causing the Southern Oscillation.

6. EI Nino Southern Oscillations 

• El Niño is a warm ocean current that replaces the cold Peruvian current every 2 to 5 years.
• It is linked to pressure changes in the Pacific and Indian Oceans.
• This phenomenon is called El Niño Southern Oscillation (ENSO).

7. Mawsynram receives the highest rainfall in the world

• Located at the head of a funnel-shaped valley in the Khasi Hills.
• Unique topography and wind direction cause extreme rainfall, making it the wettest place on Earth.

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8. The rainfall decreases from South to North 

• Southwest Monsoons originate from the Indian Ocean and split into branches due to the shape of the Indian Peninsula.
• Trivandrum receives over 200 cm of rainfall.
• Delhi, being inland, gets only around 50 cm.
• Arabian Sea branch:
  1. Hits the Western Ghats, causing heavy rainfall.
  2. Flows parallel to the Aravallis, leading to low rainfall in Jodhpur (less than 25 cm).

9. The Western Ghats receive more rain from the southwest monsoons than the Eastern Ghats because:

Map showing the position of Western and Eastern Ghats

• The Arabian Sea branch of the monsoon is onshore.
• These winds are forced to rise and cause heavy rains.
• By the time these winds reach the east coast, most of the moisture is lost.
• The winds are offshore, so they are given less rain.
• The Eastern Ghats lies on the leeward/rain-shadow area, hence it gets less rain.

Indian would have been an arid land or dessert if there had been no phenomena of monsoons :

• Indian receives 75 to 90% of the rainfall from the monsoons.
• These monsoons winds occur due to the uneven heating of land and sea.
• The mighty Himalayas check the two branches of southwest monsoons, the Arabian Sea branch and the Bay of Bengal branch. 
• These, cover the whole of India thus preventing it from becoming a desert.

Important Differences Between:  

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1. Equable Climate & Extreme Climate

2. Rainfall and Precipitation

3. South-West Monsoons and Retreating Monsoons

  

4. Loo and Cold Wave

 

5. South-West Monsoons and North-East Monsoons

 

Question for Important Points & Differences: Climate

Try yourself:Which of the following is a significant difference between South West Monsoons and Retreating Monsoons?
 

• A.

  South West Monsoons are dry winds, while Retreating Monsoons are wet winds.
   
• B.

  South West Monsoons occur during the summer months, while Retreating Monsoons occur during the winter months.
• C.

  South West Monsoons are responsible for the majority of India's annual rainfall, while Retreating Monsoons contribute relatively less rainfall.
• D.

  South West Monsoons affect only the southern and eastern parts of India, while Retreating Monsoons affect the entire country.
   

Explanation

South West Monsoons, also known as the summer monsoons, occur during the months of June to September. They are moist winds that blow from the southwest, bringing heavy rainfall to most parts of India. These monsoons are responsible for approximately 75% of India's annual rainfall.

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