Climate, Class 11 Geography (India: Physical Environment)

What Climate is about

Weightage: This chapter is part of Unit III, Climate, Vegetation and Soil, of India: Physical Environment, which carries 12 of the 70 theory marks in the school annual exam together with Natural Vegetation. Map work carries a further 5 marks for each book.Source: CBSE Geography (029) syllabus 2026-27, Class XI course structure

Key concepts

Weather, climate and monsoon; unity and diversity

NCERT section Unity and Diversity in the Monsoon Climate

Weather vs climate: weather is the momentary state of the atmosphere and changes quickly (within a day or week); climate is the average over a long period and changes imperceptibly (noticeable after 50 years or more). Elements: temperature, pressure, wind direction and velocity, humidity, precipitation.

Monsoon: climate associated with a seasonal reversal in wind direction.

Unity: the monsoon regime unites India with the rest of South-east Asia.

Diversity (sub-types of monsoon climate): variations in winds, temperature and rainfall, rhythm of seasons, and wetness or dryness.

Aspect	Examples from the chapter
Seasonal temperature	Western Rajasthan up to 55°C in summer; -45°C around Leh in winter; Churu 50°C+ on a June day while Tawang barely 19°C; Drass -45°C on a December night while Thiruvananthapuram or Chennai 20-22°C
Daily range	Kerala and Andamans: day-night difference only 7-8°C; Thar: day about 50°C, night 15-20°C
Type of precipitation	Snow in the Himalayas, rain elsewhere
Amount	Cherrapunji and Mawsynram (Khasi Hills) over 1,080 cm; Jaisalmer rarely over 9 cm; Tura (Garo Hills) can get in one day what Jaisalmer gets in 10 years; < 10 cm in the north-west Himalayas and western deserts, > 400 cm in Meghalaya
Timing	Ganga delta and Odisha coast hit by storms every 3rd-5th day in July-August while the Coromandel coast stays dry; most of India rains in June-September, but coastal Tamil Nadu gets rain at the start of winter

Despite these, India's climate is monsoonal in rhythm and character.

Worked example

Using the chapter's figures, how many times more rain does Mawsynram receive than Jaisalmer in a year? What does this show? (2 marks)

Try it first, then show the solutionSolution

1. Mawsynram over 1,080 cm; Jaisalmer about 9 cm: 1,080 ÷ 9 = 120 times.
2. It shows the great regional diversity within India's single monsoon climate.

Answer: About 120 times; striking diversity within a monsoon climate.

Factors determining the climate of India

NCERT section Factors Determining the Climate of India

Factor	Effect
Latitude	The Tropic of Cancer crosses central India. South of it: tropical, high temperatures all year with small daily and annual ranges. North of it: sub-tropical and temperate, extreme climate with high daily and annual ranges
Himalayas	An effective climatic divide: a shield against cold northern winds from near the Arctic Circle across central and eastern Asia; they trap the monsoon winds, forcing them to shed moisture within the subcontinent
Distribution of land and water	Indian Ocean on three sides, mountain wall in the north; water heats and cools slowly, land quickly; this differential heating creates different pressure zones by season, causing the reversal of monsoon winds
Distance from the sea	Coastal areas have an equable climate (people of Mumbai and the Konkan barely know extremes); interior places like Delhi, Kanpur and Amritsar have strong seasonal contrasts
Altitude	Temperature falls with height (thin air): Agra 16°C vs Darjiling 4°C in January at the same latitude
Relief	Affects temperature, pressure, wind and rainfall: windward Western Ghats and Assam get heavy June-September rain while the southern plateau stays dry on the leeward side

Worked example

Agra and Darjiling lie at about the same latitude, yet January temperatures are 16°C and 4°C. Explain. (2 marks)

Try it first, then show the solutionSolution

1. Temperature decreases with height because the air is thinner.
2. Darjiling is in the mountains, much higher than Agra on the plains, so it is 12°C colder despite the same latitude.

Answer: Altitude: Darjiling is much higher, so it is colder.

Onset of the monsoon, ITCZ and jet streams

NCERT section The Nature of Indian Monsoon

Puzzle: despite centuries of observation, no single theory explains the monsoon fully; a breakthrough came from studying it at the global level. Key aspects: onset and break.

Differential heating (late 19th-century view): in April-May the sun shines vertically over the Tropic of Cancer; the landmass north of the Indian Ocean heats intensely, forming an intense low over north-west India. The Indian Ocean stays relatively high pressure (water heats slowly). The low attracts the south-east trades across the equator, helping the ITCZ shift north. The south-west monsoon is thus a continuation of the south-east trades deflected towards India after crossing the equator between 40°E and 60°E.

ITCZ (box): a low-pressure zone at the equator where trades converge and air ascends. In July it lies around 20°N-25°N over the Gangetic plain (the monsoon trough), encouraging a thermal low over north and north-west India. Southern trades cross the equator between 40°E and 60°E and, deflected by the Coriolis force, blow south-west to north-east: the south-west monsoon. In winter the ITCZ moves south and winds reverse: the north-east monsoon.

Jet streams: the ITCZ shift is linked to the westerly jet stream pulling back from its position over the northern plain (south of the Himalayas). Only then does the easterly jet stream establish itself along 15°N; it is held responsible for the burst of the monsoon.

Entry: sets in over the Kerala coast by 1 June, reaches Mumbai and Kolkata between 10 and 13 June, covers the whole subcontinent by mid-July (Figure 4.2).

Worked example

Why are the south-west monsoon winds called 'deflected south-east trades'? (2 marks)

Try it first, then show the solutionSolution

1. The low pressure over north-west India and the northward-shifted ITCZ attract the south-east trades of the southern hemisphere across the equator (40°E-60°E).
2. After crossing, the Coriolis force deflects them to blow from the south-west, so they arrive as the south-west monsoon.

Answer: They are south-east trades pulled across the equator and turned south-westerly by the Coriolis force.

Break in the monsoon, El Nino and forecasting

NCERT section The Nature of Indian Monsoon

Break in the monsoon: during the south-west monsoon, if after a few rainy days rain fails for one or more weeks. Such dry spells are common. Causes differ:

• Northern India: rain-bearing storms are not frequent along the monsoon trough (ITCZ).
• West coast: winds blow parallel to the coast.

El Nino (box): a complex weather system appearing every 3-7 years, bringing drought, floods and extremes worldwide. Warm water appears off Peru (East Pacific), raising coastal water temperature by about 10°C; NCERT describes it as an extension of the warm equatorial current temporarily replacing the cold Peruvian (Humboldt) current. Results: distortion of equatorial atmospheric circulation; irregular evaporation; fewer plankton and so fewer fish. 'El Nino' means 'Child Christ', as it appears around Christmas (summer in Peru). Used in India for long-range monsoon forecasting.

Understanding the monsoon (box): the intensity of south-west monsoon winds and the Southern Oscillation can be measured by the pressure difference between Tahiti (about 20°S, 140°W, French Polynesia) and Port Darwin (12°30'S, 131°E, northern Australia). The IMD forecasts monsoon behaviour using 16 indicators.

Worked example

Why do breaks in the monsoon occur over the west coast? (1 mark)

Try it first, then show the solutionSolution

1. NCERT links west-coast dry spells to wind direction.
2. When winds blow parallel to the coast, they are not forced up the Ghats, so rain fails.

Answer: Winds blow parallel to the coast.

The cold weather and hot weather seasons

NCERT section The Rhythm of Seasons

IMD recognises four seasons: cold weather, hot weather, south-west monsoon, retreating monsoon.

Cold weather season

• Begins by mid-November in north India; December and January are coldest in the northern plain; mean daily temperature below 21°C; nights can fall below freezing in Punjab and Rajasthan.
• Reasons for severe north Indian cold: (i) continental location far from the sea (Punjab, Haryana, Rajasthan); (ii) snowfall in nearby Himalayas creates cold waves; (iii) around February, cold winds from the Caspian Sea and Turkmenistan bring cold waves with frost and fog to the north-west.
• Peninsula: no well-defined cold season; coastal temperatures barely change (sea and nearness to the equator); Thiruvananthapuram January mean maximum 21°C, June 29.5°C; Western Ghats hills stay cooler.
• Pressure and winds: around 22 December the sun is over the Tropic of Capricorn; feeble high pressure over the northern plain, slightly lower in the south (1019 mb isobar in the north-west, 1013 mb far south); light winds (3-5 km/h) blow outward: westerly or north-westerly down the Ganga valley, northerly in the delta, north-easterly over the Bay of Bengal.
• Western disturbances: shallow cyclonic depressions from the east Mediterranean cross West Asia, Iran, Afghanistan, Pakistan, picking up moisture from the Caspian Sea and Persian Gulf.
• Rainfall: winter monsoons give little rain (land to sea, low humidity, anticyclonic circulation). Exceptions: (i) Mediterranean temperate cyclones give rain in Punjab, Haryana, Delhi, western UP (meagre but beneficial for rabi), snow in the lower Himalayas that feeds summer river flow; decreases west to east and north to south; Delhi about 53 mm; Punjab and Bihar 25-18 mm; (ii) occasional rain in central India and the northern peninsula; (iii) Arunachal Pradesh and Assam 25-50 mm; (iv) October-November: the north-east monsoon picks up moisture over the Bay of Bengal and gives torrential rain to the Tamil Nadu coast, southern Andhra Pradesh, south-east Karnataka and south-east Kerala.

Hot weather season

• March: sun moves north; April-June are summer months in the north; most of India 30-32°C; March highest about 38°C on the Deccan; April 38-43°C in Gujarat and MP; May about 48°C in the north-west.
• South India: milder (26-32°C), oceans moderate; Western Ghats hills below 25°C; on coasts isotherms run north-south; mean minimum rarely below 26°C.
• Pressure and winds: ITCZ moves north to about 25°N in July; the monsoon trough extends from the Thar to Patna and Chotanagpur; south-westerly winds on the west coast and the coast of West Bengal-Bangladesh, easterly or south-easterly over north Bengal and Bihar (displaced equatorial easterlies).
• Loo: hot, dry afternoon winds in the north-west, often into midnight; May dust storms in Punjab, Haryana, eastern Rajasthan and UP bring respite; contact of dry and moist air causes violent local storms with hail.
• Famous local storms: mango showers (Kerala and coastal Karnataka; help mangoes ripen), blossom showers (coffee flowers in Kerala), Nor'westers ('Kalbaisakhi' in Bengal, 'Bardoisila' in Assam; useful for tea, jute, rice), loo (Punjab to Bihar, strongest between Delhi and Patna).

Worked example

Why is winter rain in north-west India important even though it is small in amount? (2 marks)

Try it first, then show the solutionSolution

1. Weak temperate cyclones from the Mediterranean bring rain to Punjab, Haryana, Delhi and western UP; though meagre, it is highly beneficial for rabi crops.
2. In the lower Himalayas it falls as snow, which sustains Himalayan river flow in summer.

Answer: It helps rabi crops and its snow feeds rivers in summer.

The south-west monsoon and retreating monsoon seasons

NCERT section The Rhythm of Seasons

South-west monsoon season

• By early June the intensified low over the north-west attracts the south-east trades; crossing the equator over warm currents, they gather moisture and turn south-westerly.
• Rain begins abruptly; the sudden onset of moist winds with thunder and lightning is the 'break' or 'burst' of the monsoon; first week of June on the coasts of Kerala, Karnataka, Goa, Maharashtra, first week of July in the interior; day temperature falls 5-8°C between mid-June and mid-July.
• Two branches:
• Arabian Sea branch: (i) blocked by the Western Ghats, climbs 900-1,200 m, cools and gives 250-400 cm to the windward side and coastal plain; descending east, it warms and gives little rain: the rain-shadow (compare Kozhikode, Mangalore with Pune, Bengaluru); (ii) strikes north of Mumbai, moves along the Narmada and Tapi valleys into central India; Chotanagpur gets 15 cm from it; then joins the Bay branch in the Ganga plains; (iii) strikes Saurashtra and Kachchh, passes over west Rajasthan and the Aravalis with scanty rain; joins the Bay branch in Punjab and Haryana; together they bring rain to the western Himalayas.
• Bay of Bengal branch: strikes Myanmar and south-east Bangladesh; the Arakan Hills deflect much of it into India; it enters West Bengal and Bangladesh from the south and south-east; splits under the Himalayas and the north-west thermal low: one arm west along the Ganga plains to Punjab, the other up the Brahmaputra valley; a sub-branch strikes the Garo and Khasi hills: Mawsynram, on the crest of the Khasi hills, gets the highest average annual rainfall in the world.
• Tamil Nadu stays dry because its coast is parallel to the Bay branch and it lies in the rain-shadow of the Arabian Sea branch.

Retreating monsoon season (October-November)

• By end-September the monsoon weakens as the trough moves south with the sun; it retreats from western Rajasthan by the first week of September, from Rajasthan, Gujarat, western Ganga plain and Central Highlands by the end of September; low pressure over the northern Bay by early October, over Karnataka and Tamil Nadu by early November, gone from the Peninsula by mid-December.
• Clear skies, rising temperature, moist land: oppressive 'October heat'; temperatures fall fast in the second half of October in the north.
• Dry in north India but rainy in the eastern Peninsula, where October and November are the rainiest months: cyclonic depressions from the Andaman Sea cross the east coast; destructive cyclones hit the Godavari, Krishna and Kaveri deltas; much of the Coromandel coast's rain comes from them; fewer in the Arabian Sea.

Traditional Indian seasons: six two-month seasons: Vasanta (March-April), Grishma (May-June), Varsha (July-August), Sharada (September-October), Hemanta (November-December), Shishira (January-February); suited to north and central India, not the south.

Worked example

Why does the Tamil Nadu coast remain dry during the south-west monsoon? (2 marks)

Try it first, then show the solutionSolution

1. The Tamil Nadu coast lies parallel to the Bay of Bengal branch, so those winds blow along it rather than onto it.
2. It lies in the rain-shadow of the Arabian Sea branch, which loses its moisture on the Western Ghats.

Answer: Parallel to the Bay branch and in the rain-shadow of the Arabian Sea branch.

Distribution of rainfall and monsoon in economic life

NCERT section The Rhythm of Seasons

Average annual rainfall: about 125 cm, with great spatial variation (Figure 4.4).

Category	Amount	Areas
High	> 200 cm	West coast, Western Ghats, sub-Himalayan north-east, Meghalaya hills; parts of Khasi and Jaintia hills > 1,000 cm; (Brahmaputra valley and adjoining hills < 200 cm)
Medium	100-200 cm	South Gujarat, east Tamil Nadu, north-eastern Peninsula (Odisha, Jharkhand, Bihar, eastern MP), northern Ganga plain along the sub-Himalaya, Cachar valley, Manipur
Low	50-100 cm	Western UP, Delhi, Haryana, Punjab, J&K, eastern Rajasthan, Gujarat, Deccan Plateau
Inadequate	< 50 cm	Parts of the Peninsula (Andhra Pradesh, Karnataka, Maharashtra), Ladakh, most of western Rajasthan

Snowfall is limited to the Himalayan region.

Monsoon and economic life:
1. The monsoon is the axis of the agricultural cycle; about 64 per cent of people depend on agriculture, which depends on the south-west monsoon.
2. Except the Himalayas, temperatures everywhere stay above the threshold for crops all year.
3. Regional variations allow many kinds of crops.
4. Variability brings droughts or floods somewhere every year.
5. Prosperity depends on timely, well-distributed rain; failure hurts unirrigated regions most.
6. Sudden burst causes soil erosion.
7. Winter rain from temperate cyclones helps rabi crops.
8. Regional climates are reflected in varied food, clothes and houses.

Worked example

State two ways in which the monsoon affects India's economic life. (2 marks)

Try it first, then show the solutionSolution

1. About 64 per cent of people depend on agriculture, which depends on the south-west monsoon: it is the axis of the agricultural cycle.
2. Rainfall variability brings droughts or floods every year in some areas, and failure of rain hurts unirrigated regions.

Answer: It drives agriculture and its variability causes droughts and floods.

Global warming

NCERT section Global Warming

• Climate has always changed (geological evidence of past ice cover), but besides natural causes, large-scale industrialisation and polluting gases cause global warming via the greenhouse effect.
• Carbon dioxide from burning fossil fuels is a major concern and is increasing. Methane, chlorofluorocarbons and nitrous oxide, though in much smaller concentrations, are better absorbers of long-wave radiation than CO2 and more effective at enhancing the greenhouse effect.
• Mean annual surface temperature has risen over the past 150 years; projected rise about 2°C by 2100.
• Effects: melting polar ice caps and mountain glaciers; more ocean water; sea level rise of about 48 cm by the end of the 21st century (current prediction), increasing annual flooding; spread of insect-borne diseases like malaria; shifting climatic boundaries (some regions wetter, others drier); shifts in agricultural patterns; changes for people and ecosystems.

Worked example

Why are methane and CFCs important greenhouse gases even though they are present in small amounts? (2 marks)

Try it first, then show the solutionSolution

1. NCERT says methane, CFCs and nitrous oxide are better absorbers of long-wave radiation than carbon dioxide.
2. So even small concentrations enhance the greenhouse effect strongly.

Answer: They absorb long-wave radiation more effectively than CO2.

Climate in real life

Each concept, met in an everyday situation. Read the situation, answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Topics in this chapter

• The Indian Monsoon: Onset, ITCZ, Jet Streams, Breaks, El Nino and Forecasting
• Weather and Climate, Unity and Diversity and the Factors Controlling the Climate of India

Climate: key facts

Extremes

• •55°C western Rajasthan (summer)
• •-45°C Leh/Drass (winter)
• •1,080 cm Cherrapunji-Mawsynram
• •9 cm Jaisalmer

Basis of the map items.

Onset dates

1. 1.Kerala 1 June
2. 2.Mumbai and Kolkata 10-13 June
3. 3.whole country mid-July

Burst on coasts in the first week of June, interior first week of July.

ITCZ

July: 20°N-25°N (monsoon trough over the Gangetic plain); winter: moves south

Trades cross the equator at 40°E-60°E.

Jet streams

1. 1.Westerly jet withdraws
2. 2.easterly jet along 15°N
3. 3.burst of monsoon

Linked to the ITCZ shift.

Southern Oscillation index

Pressure difference: Tahiti (20°S, 140°W) - Darwin (12°30'S, 131°E)

IMD uses 16 indicators.

Arabian Sea branch

1. 1.Western Ghats 900-1,200 m
2. 2.windward 250-400 cm
3. 3.rain shadow east; Chotanagpur 15 cm

Three sub-branches.

Rainfall categories

• •> 200
• •100-200
• •50-100
• •< 50 cm; average about 125 cm

Khasi-Jaintia parts > 1,000 cm.

Traditional seasons

$Vasanta(Mar-Apr),Grishma(May-Jun),Varsha(Jul-Aug),Sharada(Sep-Oct),Hemanta(Nov-Dec),Shishira(Jan-Feb)$

Six two-month seasons.

Global warming projections

About +2°C by 2100; sea level about +48 cm by the end of the century

Per the chapter's current prediction.

Climate: diagrams to practise

Practise each one on paper: draw it from the checklist, then tick off every label.

Climate: map work

The places on the official CBSE map list for this chapter. Find each one on an outline map of India and practise marking it.

How the school exam asks Climate

The question patterns to expect, and the method that works for each.

Tricks to remember Climate

Short memory aids. Say each one aloud once, then use it on a question the same day.

• Climate factors

  'LH-LDAR': Latitude, Himalayas, Land-water, Distance from sea, Altitude, Relief.

  Use it when: Factors of India's climate.

• Onset dates

  '1 June Kerala, 10-13 June Mumbai and Kolkata, mid-July all India'.

  Use it when: Monsoon arrival.

• IMD seasons

  'Cold, Hot, Wet, Retreat'.

  Use it when: Four seasons.

• Local storms

  'Mangoes, Coffee, Kalbaisakhi, Loo' from south to north.

  Use it when: Hot-season storms.

• Traditional seasons

  'Very Good Village Shows Happy Smiles': Vasanta, Grishma, Varsha, Sharada, Hemanta, Shishira.

  Use it when: Six Indian seasons.

Climate: exam-level solved questions

Ordered from exam level to HOTS. Cover the solution, write your own, then compare step by step.

Case-study practice (Section E style)

Read the situation, then answer every part. In a school exam set on the board pattern this is a 4-mark question split into 1 + 1 + 2 marks.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Where students lose marks in Climate

The slips examiners see most often, and what to write instead.

• ✗Mistake: Writing that the Bay branch enters Bengal from the south-west

  Students apply the branch name literally.

  Wrong working

  The Bay of Bengal branch enters West Bengal from the south-west.

  Right working

  Deflected by the Arakan Hills, it enters West Bengal and Bangladesh from the south and south-east.

  ✓Do this: Arakan turns it.

  Usually costs: 1 mark.

• ✗Mistake: Explaining Tamil Nadu's dry summer by 'no monsoon reaches it'

  Over-simplification.

  Wrong working

  Tamil Nadu gets no monsoon winds.

  Right working

  Its coast lies parallel to the Bay branch and in the rain-shadow of the Arabian Sea branch.

  ✓Do this: Two reasons: parallel and shadow.

  Usually costs: 1-2 marks.

• ✗Mistake: Confusing break and burst

  NCERT uses 'break' in both phrases.

  Wrong working

  A break in the monsoon is its sudden onset.

  Right working

  Burst (also called 'break' of the monsoon) is the abrupt onset; a break in the monsoon is a dry spell of a week or more during the season.

  ✓Do this: Burst = start; break in = gap.

  Usually costs: 1 mark.

• ✗Mistake: Placing the highest rainfall at Cherrapunji alone

  Older textbooks.

  Wrong working

  Cherrapunji gets the world's highest rainfall.

  Right working

  Mawsynram, on the crest of the Khasi hills, gets the highest average annual rainfall in the world (both exceed 1,080 cm).

  ✓Do this: Mawsynram is the record holder.

  Usually costs: 1 mark and a map mark.

• ✗Mistake: Mixing traditional seasons with months

  Six names to learn.

  Wrong working

  Varsha = May-June.

  Right working

  Grishma = May-June; Varsha = July-August.

  ✓Do this: Order: Vasanta, Grishma, Varsha, Sharada, Hemanta, Shishira from March.

  Usually costs: 1 mark.

NCERT exercise guide: Climate

What each exercise in the NCERT chapter tests, how to approach it, and a question of the same kind solved step by step. Questions here are written in our own words.

Practice questions on Climate

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQExam level

   Thiruvananthapuram records a daily range of only about 7-8°C and little difference between its warmest and coolest months. The main reason is that:
   (a) it lies in the rain shadow of the Western Ghats
   (b) it is near the sea and close to the equator
   (c) it receives western disturbances
   (d) it has a continental location

   Hint

   Maritime influence and low latitude.

   Answer

   (b) It is near the sea and close to the equator, so temperatures stay high and even through the year.

2. Q2 · 1 mark · MCQExam level

   The easterly jet stream that triggers the burst of the monsoon sets in along:
   (a) 5°N
   (b) 15°N
   (c) 25°N
   (d) 35°N

   Hint

   After the westerly jet withdraws.

   Answer

   (b) 15°N.

3. Q3 · 1 mark · Assertion-reasonHarder exam level

   Assertion (A): Winter monsoons do not bring rain to most of India.
   Reason (R): They blow from land to sea, carry little humidity, and anticyclonic circulation on land reduces rainfall.
   Choose (a)-(d).

   Hint

   NCERT's own reasons.

   Answer

   (a).

4. Q4 · 2 marks · Short answerExam level

   In July the low-pressure belt where winds converge over India is called the monsoon trough. Locate it, say what it is a shifted form of, and state one effect on wind direction. (2 marks)

   Hint

   The ITCZ moves north with the sun.

   Answer

   It lies at about 20°N-25°N over the Gangetic plain; it is the Inter Tropical Convergence Zone, the zone of converging trade winds and rising air, shifted north in summer. It draws in the south-east trades from the southern hemisphere, which turn into the south-west monsoon after crossing the equator.

5. Q5 · 3 marks · Short answerHarder exam level

   Why is north India so cold in the cold weather season? Give three reasons. (3 marks)

   Hint

   Continentality, snow, cold winds.

   Answer

   (i) Punjab, Haryana and Rajasthan are far from the sea and have a continental climate; (ii) snowfall in nearby Himalayan ranges creates cold waves; (iii) around February cold winds from the Caspian Sea and Turkmenistan bring cold waves with frost and fog.

6. Q6 · 2 marks · Short answerExam level

   Wheat farmers in Punjab welcome light rain in January. Name the weather systems that bring it, trace their route to India and explain why the rain matters for the rabi crop. (2 marks)

   Hint

   Western disturbances.

   Answer

   Shallow temperate cyclonic depressions (western disturbances) originate over the east Mediterranean Sea, cross West Asia, Iran, Afghanistan and Pakistan, and pick up moisture from the Caspian Sea and Persian Gulf. Though small in amount, the winter rain is highly beneficial for rabi crops such as wheat.

7. Q7 · 3 marks · Short answerHOTS / competency

   Suppose a farmer in the Deccan near Pune notices that coastal Konkan gets far more rain than his village though both lie in the path of the same monsoon winds. Explain using the chapter. (3 marks)

   Hint

   Windward and leeward.

   Answer

   The Arabian Sea branch is forced up the Western Ghats (900-1,200 m), cools and gives 250-400 cm to the windward Konkan side. Descending east, the winds warm and lose humidity, so the Pune side lies in the rain-shadow area with much less rain.

8. Q8 · 3 marks · Short answerHOTS / competency

   How might global warming affect India's coasts and climate? (3 marks)

   Hint

   Sea level, disease, boundaries.

   Answer

   A sea-level rise of about 48 cm by the end of the century would increase annual flooding of coasts; insect-borne diseases like malaria may spread; climatic boundaries may shift, making some regions wetter and others drier, changing agricultural patterns.

9. Q9 · 3 marks · Short answerHarder exam level

   Compare the cold weather season in north India and the Peninsula. (3 marks)

   Hint

   Temperature and range.

   Answer

   North India: from mid-November; December-January coldest; mean daily temperature below 21°C; nights can go below freezing in Punjab and Rajasthan. Peninsula: no well-defined cold season; coastal temperatures change little because of the sea and nearness to the equator (Thiruvananthapuram January maximum 21°C); hills of the Western Ghats cooler.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.What does 'monsoon' mean?Show answer

   Climate associated with a seasonal reversal in the direction of winds.

2. 2.Between which longitudes do the trade winds cross the equator to become the south-west monsoon?Show answer

   40°E and 60°E.

3. 3.What is a break in the monsoon?Show answer

   A dry spell of one or more weeks during the south-west monsoon after some rainy days.

4. 4.What does 'El Nino' mean?Show answer

   'Child Christ', because it appears around Christmas.

5. 5.How many indicators does the IMD use to forecast the monsoon?Show answer

   16.

6. 6.Which hills deflect the Bay of Bengal branch into India?Show answer

   The Arakan Hills along the coast of Myanmar.

7. 7.What is the average annual rainfall of India?Show answer

   About 125 cm.

8. 8.What share of Indians depends on agriculture, according to the chapter?Show answer

   About 64 per cent.

Quick revision checklist

The night before the exam: can you do each of these without looking?

• ☐Weather momentary, climate long-term average; monsoon = seasonal reversal of winds.
• ☐Diversity: 55°C Rajasthan vs -45°C Leh/Drass; 1,080 cm Mawsynram vs 9 cm Jaisalmer.
• ☐Factors: latitude, Himalayas, land-water, distance from sea, altitude (Agra 16°C vs Darjiling 4°C), relief.
• ☐Onset: heating low in NW India; ITCZ at 20°-25°N in July; trades cross at 40°-60°E; easterly jet at 15°N.
• ☐Kerala 1 June, Mumbai-Kolkata 10-13 June, all India mid-July; breaks when storms are few or winds parallel to coast.
• ☐El Nino every 3-7 years; Tahiti-Darwin pressure; IMD 16 indicators.
• ☐Cold season: below 21°C; western disturbances; north-east monsoon rain on Tamil Nadu coast.
• ☐Hot season: up to 48°C NW; loo; mango showers, blossom showers, Kalbaisakhi.
• ☐SW monsoon: Arabian Sea branch (Ghats 250-400 cm, rain shadow) and Bay branch (Arakan, Mawsynram); Tamil Nadu dry.
• ☐Retreating: October heat; east-coast cyclones; Coromandel rain.
• ☐Rainfall 125 cm average: > 200, 100-200, 50-100, < 50 cm; monsoon = axis of agriculture; global warming +2°C, +48 cm sea level.

Climate: frequently asked questions