Class 9 Social Science Geography Chapter 4: Climate

1. Short Notes for Revision

Climate vs Weather

  • Climate: Sum of weather conditions over a large area for a long time (30+ years); includes temperature, pressure, wind, humidity, precipitation.
  • Weather: Day-to-day atmospheric state at a specific time/place; fluctuates often, e.g., sudden rain or heatwave.
  • Elements: Same for both—temperature, atmospheric pressure, wind, humidity, precipitation; patterns lead to seasons (winter, summer, rainy).

Monsoon Climate

  • Type: India’s climate is monsoon (from Arabic ‘mausim’ = season); seasonal wind reversal; found in south/southeast Asia.
  • Unity with Variations: Overall uniform pattern but regional differences in temperature (e.g., 50°C Rajasthan summer vs 20°C Pahalgam; -45°C Drass winter vs 22°C Trivandrum).
  • Precipitation Variations: Snow in Himalayas; rain elsewhere; 400+ cm Meghalaya vs <10 cm Ladakh/Rajasthan; most rain Jun-Sep, but TN coast Oct-Nov.
  • Contrasts: High day-night temp difference in interiors/deserts (Thar: 50°C day to 15°C night); minimal in coasts (Andamans/Kerala); rainfall decreases east to west in plains.

Climatic Controls

  • Latitude: Tropic of Cancer (23.5°N) divides tropical (south) and subtropical (north) zones; affects solar energy.
  • Altitude: Temperature decreases with height; Himalayas (6,000 m avg.) block cold Central Asian winds, mild winters.
  • Pressure & Winds: Governed by subtropical high-pressure belt; NE trade winds; upper air circulation, western disturbances, tropical cyclones.
  • Distance from Sea (Continentality): Increases extremes inland (hot summers, cold winters); moderating sea effect on coasts.
  • Ocean Currents: Warm Gulf Stream-like currents warm coasts; e.g., warm currents warm western coasts in subtropics.
  • Relief: Mountains block winds, cause orographic rain (windward wet, leeward dry); e.g., Western Ghats.

Indian Monsoon

  • Mechanism: Differential heating—land heats faster than sea in summer, low pressure over NW India pulls SW monsoon from Indian Ocean; winter reverse.
  • Onset: Early Jun (Kerala), advances NW; bursts over Indo-Gangetic plains by mid-Jul.
  • Branches: Arabian Sea (heavy rain west coast) and Bay of Bengal (NE India, plains).
  • Retreat: Sep-Oct, starts NW, clears by Dec; brings clear skies, Oct-Nov cyclones in Bay.

Seasons

  • Winter (Dec-Feb): NE monsoons, dry; western disturbances bring rain/snow NW; temp 10-15°C plains, below freezing hills.
  • Summer (Mar-May): Hot, low pressure NW; Loo winds (hot dry); temp 40-50°C NW, 30-35°C south; mango showers (KE/KNT pre-monsoon).
  • Advancing Monsoon (Jun-Sep): SW winds, 75-90% annual rain; breaks into wet/dry spells; high humidity.
  • Retreating Monsoon (Oct-Nov): Clear skies, pleasant; TN rain from NE monsoons; cyclones.

Distribution of Rainfall

  • Patterns: Heavy NE/peninsula (200+ cm), moderate NW/plains (50-100 cm), low west (25-50 cm), very low deserts (<25 cm).
  • Influences: Relief (orographic), winds; uneven leads to floods/droughts.

2. Multiple Choice Questions (MCQs)

  1. Climate refers to weather conditions over a large area for: A) One day B) One week C) More than 30 years D) One year
  2. The term ‘monsoon’ derives from Arabic word meaning: A) Rain B) Wind C) Season D) Heat
  3. India’s climate is described as: A) Tropical B) Subtropical C) Monsoon type D) Desert
  4. Which place experiences -45°C in winter? A) Drass (J&K) B) Trivandrum C) Rajasthan D) Meghalaya
  5. Annual precipitation in Meghalaya is over: A) 10 cm B) 50 cm C) 100 cm D) 400 cm
  6. The Tropic of Cancer passes through which state in the east? A) Gujarat B) Mizoram C) Rajasthan D) Madhya Pradesh
  7. Himalayas prevent entry of: A) Warm winds B) Cold Central Asian winds C) Monsoon winds D) Trade winds
  8. Continentality leads to: A) Mild climate B) Extreme weather C) High rainfall D) Low temperature
  9. Western disturbances originate from: A) Bay of Bengal B) Arabian Sea C) Mediterranean Sea D) Indian Ocean
  10. Onset of monsoon is first in: A) Kerala B) Rajasthan C) Delhi D) Assam
  11. Mango showers occur in: A) Kerala and Karnataka B) Rajasthan C) Punjab D) J&K
  12. Which season has retreating monsoon? A) Winter B) Summer C) Rainy D) Post-monsoon
  13. Loo winds are: A) Cold and dry B) Hot and dry C) Humid D) Rain-bearing
  14. The branch of monsoon causing heavy rain on Western Ghats is: A) Bay of Bengal B) Arabian Sea C) Tibetan D) NE
  15. Annual rainfall percentage during monsoon season: A) 10-20% B) 30-40% C) 75-90% D) 100%
  16. Which control affects temperature with height? A) Latitude B) Altitude C) Ocean currents D) Relief
  17. Tamil Nadu receives rain mainly in: A) June-September B) October-November C) December-February D) March-May
  18. Jet Stream influences: A) Upper air circulation B) Surface winds C) Ocean currents D) Latitude
  19. Houses in Rajasthan have thick walls for: A) Insulation from heat B) Sloping roofs C) Flood protection D) Snow
  20. The leeward side of mountains is: A) Wet B) Dry C) Windy D) Cold

Answer Key: 1-C, 2-C, 3-C, 4-A, 5-D, 6-B, 7-B, 8-B, 9-C, 10-A, 11-A, 12-D, 13-B, 14-B, 15-C, 16-B, 17-B, 18-A, 19-A, 20-B

3. Very Short Answer Type Questions (VSAQs)

  1. Define climate. Answer: Average weather conditions over a large area for 30+ years.
  2. What is weather? Answer: Atmospheric state at a specific time/place.
  3. Name two elements of weather. Answer: Temperature and precipitation.
  4. From where does ‘monsoon’ originate? Answer: Arabic ‘mausim’ meaning season.
  5. Which latitude divides India into tropical and subtropical? Answer: Tropic of Cancer (23.5°N).
  6. What blocks cold winds in India? Answer: Himalayas.
  7. Define continentality. Answer: Extreme weather due to distance from sea.
  8. Name one factor causing orographic rainfall. Answer: Relief (mountains).
  9. When does monsoon onset in Kerala? Answer: Early June.
  10. What are Loo winds? Answer: Hot, dry winds in summer (NW India).
  11. Which season brings western disturbances? Answer: Winter.
  12. What are Mango showers? Answer: Pre-monsoon rains in Kerala/Karnataka.

4. Short Answer Type Questions (SAQs)

  1. Distinguish between climate and weather. Answer: Climate is long-term average conditions over large areas; weather is short-term state at a point. Climate shows patterns like seasons; weather varies daily.
  2. Why is India’s climate called monsoon type? Answer: Due to seasonal wind reversal—SW summer monsoon brings rain, NE winter is dry; affects 75-90% rainfall Jun-Sep.
  3. Explain the role of latitude in India’s climate. Answer: Tropic of Cancer splits tropical south (hot, humid) and subtropical north (wider temp range); influences solar insolation and seasons.
  4. How does altitude affect temperature? Answer: Temperature drops with height due to thinner air; e.g., hills cooler in summer; Himalayas moderate winters by blocking cold winds.
  5. Describe the effect of distance from sea. Answer: Coasts have mild climate (less extremes); interiors extreme due to continentality, e.g., hot Rajasthan summers.
  6. What are western disturbances? Answer: Extra-tropical cyclones from Mediterranean; bring winter rain/snow to NW India, aid rabi crops.
  7. Explain the onset of monsoon. Answer: Low pressure over NW India pulls SW winds from ocean; starts in Kerala (Jun), advances NW via upper air jet streams.
  8. Why do coastal areas have less temp variation? Answer: Sea’s moderating influence keeps days/nights similar; e.g., Andamans/Kerala uniform, unlike Thar Desert’s 35°C swing.
  9. Describe summer season features. Answer: Mar-May hot (40-50°C NW), low pressure, Loo winds; pre-monsoon showers in south.

5. Long Answer Type Questions (LAQs)

  1. Discuss the factors affecting India’s climate with examples. Latitude via Tropic of Cancer creates tropical-subtropical mix, with south warmer year-round. Altitude cools hills, as Himalayas block Siberian chills for milder winters. Pressure/winds drive monsoons—low summer pressure pulls SW winds, jet streams guide advance. Continentality extremes inland Rajasthan (50°C days, 15°C nights). Ocean currents warm coasts subtly, while relief causes orographic rain on Western Ghats (windward wet, Deccan dry). These interplay for diverse regions, from Meghalaya’s 400 cm rain to Ladakh’s <10 cm.
  2. Explain the mechanism of Indian monsoon and its seasonal reversal. Monsoon arises from differential heating: summer land-sea contrast creates low pressure over NW India, drawing SW winds from high-pressure southern ocean, burdened with moisture for Jun-Sep rains (75% annual). Upper jet streams (subtropical westerly) split, eastern over Tibet pulls monsoon. Winter reverses—high pressure over land pushes NE dry winds. Retreat Sep-Oct brings cyclones. This reversal, influenced by Himalayas (block winter cold, channel summer rain), ensures agriculture but uneven distribution causes floods/droughts.
  3. Describe the four seasons of India, highlighting weather patterns. Winter (Dec-Feb): Cool, dry NE winds; western disturbances bring NW rain/snow; 10-15°C plains, freezing hills. Summer (Mar-May): Rising heat (40-50°C), low pressure, Loo gusts; south gets mango showers. Advancing monsoon (Jun-Sep): SW winds, heavy rain (orographic on Ghats, cyclonic breaks); humid, 80-100 cm plains. Retreating (Oct-Nov): Clearing skies, pleasant temps; NE branch rains TN coast, Bay cyclones. Seasons reflect monsoon dominance, vital for economy but variable regionally.
  4. Analyze the distribution of rainfall in India and its causes. Rainfall varies: heavy (>200 cm) NE/Western Ghats from Bay/Arabian branches; moderate (100-200 cm) central plains; low (50-100 cm) Deccan/NW; scanty (<50 cm) Rajasthan. Orographic effect—Himalayas/Ghats lift moist winds for rain, leeward dry. Winds: SW monsoon 87%, NE 13%; uneven due to depressions. Relief deflects rain shadows (e.g., rain in Mawsynram, drought in Jaisalmer). This influences crops, but climate change intensifies extremes—vital for irrigation planning.
  5. How does relief influence climate? Give examples. Mountains act as barriers, causing orographic precipitation on windward sides while rain shadows dry leewards. Himalayas block cold NW winds for mild Indian winters, channel monsoons for Ganga rains but dry Trans-Himalayas. Western Ghats trap Arabian Sea moisture (Cherrapunji-like in Ghats), Deccan drier. Eastern Ghats less effective, allowing rain inland. Locally, Vindhyas moderate central temps. Relief thus creates microclimates, e.g., wet Kerala vs arid Rajasthan, shaping agriculture and settlements.

6. Source-Based / Case-Based Assessment Questions

Source Extract (from NCERT Text on Climatic Variations): “In summer, the mercury occasionally touches 50°C in some parts of the Rajasthan desert, whereas it may be around 20°C in Pahalgam in Jammu and Kashmir. On a winter night, temperature at Drass in Jammu and Kashmir may be as low as minus 45°C. Thiruvananthapuram, on the other hand, may have a temperature of 22°C… Annual precipitation varies from over 400 cm in Meghalaya to less than 10 cm in Ladakh and western Rajasthan.”

  1. What is the summer temperature contrast between Rajasthan and Pahalgam? (Factual Recall) Answer: 50°C in Rajasthan vs 20°C in Pahalgam.
  2. Name the coldest winter spot mentioned. (Factual Recall) Answer: Drass (-45°C).
  3. Why does Trivandrum have milder winters? (Concept Explanation) Answer: Coastal location moderates temperatures via sea influence.
  4. Calculate the precipitation range in India. (Application) Answer: From <10 cm (Ladakh/Rajasthan) to >400 cm (Meghalaya).
  5. Infer the impact of latitude on these variations. (Analytical) Answer: Subtropical north has extremes; tropical south milder due to solar angle.
  6. Suggest reasons for low rainfall in Ladakh. (Critical Thinking) Answer: Rain shadow of Himalayas blocks monsoons; high altitude reduces moisture.

Answer Key: (Builds from facts to analysis; use for varied skill practice.)

7. Solved Exercise-End Questions (NCERT Solutions)

1. Choose the right answer from the four alternatives given below.

(i) Which one of the following places has the lowest range of temperature throughout the year? (a) Chennai (b) Delhi (c) Jaisalmer (d) Thiruvananthapuram Answer: (d) Thiruvananthapuram (Coastal, minimal day-night/seasonal variation.)

(ii) Which one of the following is not a controlling factor of climate? (a) Latitude (b) Altitude (c) Distance from the sea (d) Population density Answer: (d) Population density (Climatic controls are physical, not human.)

(iii) Which of the following is not a monsoon wind? (a) South-west monsoon (b) North-east monsoon (c) Western disturbances (d) Retreating monsoon Answer: (c) Western disturbances (Extra-tropical, not monsoon reversal.)

(iv) Which of the following is the driest place in India? (a) Leh (b) Jaisalmer (c) Jodhpur (d) Bikaner Answer: (a) Leh (<10 cm annual rain, rain shadow.)

2. Answer the following questions briefly.

(i) Why does the word ‘monsoon’ mean ‘season’? Answer: Derived from Arabic ‘mausim’ (season), referring to predictable seasonal wind shifts bringing rain.

(ii) What is the difference between the climates of northern and southern parts of India? Answer: North (subtropical) has greater temp extremes and winter cold; south (tropical) milder, more uniform due to latitude.

(iii) Which winds are responsible for the rainfall along the Malabar Coast? Answer: Arabian Sea branch of SW monsoon, orographic lift on Western Ghats.

(iv) What is meant by ‘western disturbances’? Answer: Temperate cyclones from Mediterranean, bring winter rain/snow to NW India.

(v) Why is there a difference between day and night temperatures in the Thar Desert? Answer: Continentality—far from sea, rapid daytime heating/cooling of sand.

(vi) Name the months when the retreat of the monsoon starts from the north-western part of India. Answer: September, advancing south by October-November.

3. Why is the climate of India called ‘monsoon’ climate?

Answer: Seasonal wind reversal—SW summer winds bring 75-90% rain (Jun-Sep), NE winter dry; ‘mausim’ signifies this predictable seasonal pattern, unique to south Asia.

4. Which part of India experiences the highest and the lowest temperatures in summer and winter?

Answer: Highest summer: Rajasthan desert (50°C); lowest winter: Drass, J&K (-45°C). Highest winter: South coasts (22°C Trivandrum); lowest summer: Hills like Pahalgam (20°C).

5. Name the factors affecting the climate of India.

Answer: Latitude (tropical-subtropical), altitude (cooling), pressure/winds (monsoon), distance from sea (continentality), ocean currents (coastal moderation), relief (orographic rain).

Map Skills

On an outline map of India, mark and label the following: (i) Areas receiving more than 400 cm annual rainfall. (ii) Areas with less than 20 cm annual rainfall. (iii) Direction of SW monsoon winds. Answer: (i) Western Ghats, NE hills (Meghalaya); (ii) Ladakh, western Rajasthan; (iii) Arrows from SW ocean to NE land.

Project/Activity

Collect information on any one tropical cyclone that affected India recently. Answer: (Example: Cyclone Amphan, 2020—hit WB/Odisha, winds 185 km/h, Rs 12,000 crore damage, 100+ deaths; evacuations saved lives; retreating monsoon season.)

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