1. What is a Monsoon?
The word “monsoon” comes from the Arabic word “mausim” meaning season.
Monsoon refers to seasonal reversal of winds –
winds blowing in one direction in summer and the opposite in winter.
हिंदी: Monsoon = ऐसी हवा जो मौसम के साथ दिशा बदलती है।
गर्मी में एक दिशा, सर्दी में उल्टी दिशा – यही इसकी पहचान है।
2. Why Does India Get Monsoons?
Main reasons:
- Unequal heating of land and water (Indian landmass heats faster than Indian Ocean).
- Shift of Inter-Tropical Convergence Zone (ITCZ) northwards over India in summer.
- Strong south-east trade winds from southern hemisphere turning as south-west winds when crossing the equator (Coriolis effect).
- Presence of Himalayas and highlands deflecting winds and causing rainfall.
हिंदी: गर्मियों में भारत की जमीन समुद्र से ज़्यादा गर्म हो जाती है → कम दबाव बनता है → समुद्र से नमी भरी हवा inland की तरफ चलती है → यही South-West Monsoon है।
3. South-West Monsoon Winds (Main Rainy Season)
South-West monsoon reaches India generally in early June and withdraws by September.
It has two main branches:
- Arabian Sea Branch
- Bay of Bengal Branch
4. Arabian Sea Branch
- Strikes the west coast of India, first reaching Kerala coast (onset of monsoon).
- Gives very heavy rainfall along the Western Ghats – especially on the windward (western) side.
- As it moves northwards, it brings rain to coastal Karnataka, Goa, Maharashtra (including Mumbai), Gujarat etc.
- Some part of this branch moves towards the interior and contributes to rainfall in central India and parts of Rajasthan.
हिंदी: Arabian Sea branch = पश्चिमी तट (Kerala से लेकर Mumbai, Gujarat तक) + कुछ भाग अंदर की तरफ (Central India)।
5. Bay of Bengal Branch
- Moves northwards and hits the east coast and North-East India.
- Turns towards the west and northwest after striking the hills of North-East (Garo, Khasi, Jaintia etc.).
- Causes very heavy rainfall in Meghalaya (Mawsynram, Cherrapunji) and Assam.
- Then moves westwards along the Ganga plain – giving rain to West Bengal, Bihar, UP, etc.
हिंदी: Bay of Bengal branch पहले North-East India में टकराती है (इसलिए वहाँ बहुत बारिश), फिर Ganga plain के साथ पश्चिम की ओर बढ़ती है।
6. Onset & Withdrawal of Monsoon
- Onset: generally around 1 June over Kerala coast.
- By July, monsoon covers almost the whole of India.
- Withdrawal: starts from North-West India around September and completes from southern parts by October–November.
हिंदी:
1 June (लगभग) – Kerala में शुरुआत
Sep–Oct – उत्तर-पश्चिम से वापस लौटना शुरू
Oct–Nov – देश के दक्षिण-पूर्वी हिस्सों से अंतिम वापसी
7. North-East Monsoon (Retreating Monsoon)
- After withdrawal of South-West monsoon, North-East trade winds blow from land to sea.
- They pick up some moisture from the Bay of Bengal and bring rain to the east coast of India, especially Tamil Nadu coast, parts of Andhra Pradesh and Odisha.
- This is called the Retreating Monsoon or North-East Monsoon (mainly Oct–Nov).
हिंदी: North-East Monsoon = खासकर Tamil Nadu के लिए मुख्य बारिश का मौसम (Oct–Nov)।
8. Monsoon & Agriculture in India
- Most of India’s rainfall (about 75–80%) is received during the South-West Monsoon season.
- Indian agriculture, especially Kharif crops (rice, cotton, jute, sugarcane etc.), heavily depends on monsoon rains.
- Good monsoon → good crop → economic stability; weak monsoon → drought risk.
हिंदी: “Monsoon अच्छा तो साल अच्छा” – भारत की अर्थव्यवस्था और खेती अभी भी काफी हद तक monsoon पर निर्भर है।
9. Monsoon – Irregularities & Associated Terms
- Monsoon burst – sudden onset of heavy monsoon rain after a dry or hot period.
- Break in monsoon – when normal monsoon rains temporarily stop for some days.
- Drought – long period of below-normal rainfall.
- Flood – excessive rainfall causing overflow of rivers.
हिंदी: Burst = अचानक तेज शुरुआत, Break = बीच में रुक-रुक कर चलना। दोनों शब्द अक्सर paper में पूछे जाते हैं।
📘 Practice Questions (NDA Style)
1. The word "monsoon" is derived from which language?
a) Persian b) Arabic c) Latin d) Greek
2. The onset of South-West monsoon in India is first felt at:
a) Gujarat coast b) Tamil Nadu coast c) Kerala coast d) Odisha coast
3. The two main branches of South-West monsoon are:
a) Arabian Sea and Mediterranean branches
b) Bay of Bengal and Arabian Sea branches
c) Indian Ocean and Pacific branches
d) Equatorial and Tropical branches
4. Tamil Nadu coast receives most of its rainfall from:
a) South-West monsoon b) Western Disturbances c) North-East monsoon d) Local thunderstorms
5. The heavy rainfall in Mawsynram and Cherrapunji is mainly due to:
a) Western Disturbances
b) Arabian Sea branch only
c) Bay of Bengal branch striking against hills of North-East
d) Local convection currents only
a) Persian b) Arabic c) Latin d) Greek
2. The onset of South-West monsoon in India is first felt at:
a) Gujarat coast b) Tamil Nadu coast c) Kerala coast d) Odisha coast
3. The two main branches of South-West monsoon are:
a) Arabian Sea and Mediterranean branches
b) Bay of Bengal and Arabian Sea branches
c) Indian Ocean and Pacific branches
d) Equatorial and Tropical branches
4. Tamil Nadu coast receives most of its rainfall from:
a) South-West monsoon b) Western Disturbances c) North-East monsoon d) Local thunderstorms
5. The heavy rainfall in Mawsynram and Cherrapunji is mainly due to:
a) Western Disturbances
b) Arabian Sea branch only
c) Bay of Bengal branch striking against hills of North-East
d) Local convection currents only
Answers:
1 – b) Arabic
2 – c) Kerala coast
3 – b) Bay of Bengal and Arabian Sea branches
4 – c) North-East monsoon
5 – c) Bay of Bengal branch striking against hills of North-East
1 – b) Arabic
2 – c) Kerala coast
3 – b) Bay of Bengal and Arabian Sea branches
4 – c) North-East monsoon
5 – c) Bay of Bengal branch striking against hills of North-East
Quick Recap | सार
Now you should be able to:
- Recall the most important ideas of this topic.
- Solve typical NDA-style questions from this chapter.
- Spot and avoid common traps used in competitive exams.
Self-check: 3–4 random questions उठा कर देखिए – अगर आसानी से हो रहे हैं, तो chapter strong है।
Common Exam Mistakes | आम गलतियाँ
- Concept ठीक से clear न करना और सीधे रटने की कोशिश करना।
- Question पूरी तरह पढ़े बिना answer mark कर देना।
- Figures, dates, या formulas को last step में verify न करना।
NDA में smart strategy यह है कि आसान वाले सवाल पहले, doubtful बाद में – और silly mistakes से बचना सबसे ज़रूरी है।