CLASS- IX    GEOGRAPHY: CONTEMPORARY INDIA

04.   CLIMATE

1. Introduction to Climate

In the previous chapters, we studied landforms and drainage. These, along with climate, form the three main elements of the natural environment.
Climate helps us understand why:

  • We wear woollen clothes in December
  • We feel very hot in May
  • It rains heavily in June–July

To understand these differences, we must study the climate of India.

Weather and Climate – Difference

Climate

  • Climate is the average weather condition of a large area for a long period (more than 30 years).

Weather

  • Weather is the condition of the atmosphere at a particular time.
  • Weather changes frequently, even within the same day.

Elements of Weather & Climate

  1. Temperature
  2. Atmospheric pressure
  3. Wind
  4. Humidity
  5. Precipitation

Based on common monthly weather patterns, we divide the year into seasons such as winter, summer, and rainy season.

2. Monsoon Type of Climate

  • The word “monsoon” comes from the Arabic word ‘mausim’, meaning season.
  • Monsoon means seasonal reversal of wind direction.
  • India has a monsoon type of climate.

In Asia, this type of climate is mainly found in South and Southeast Asia.

Even though the general pattern is similar, there are regional variations in temperature and rainfall.

3. Temperature Variations in India

Examples of temperature differences:

  • Rajasthan desert (summer): up to 50°C
  • Pahalgam (J&K): around 20°C
  • Drass (winter night): –45°C
  • Thiruvananthapuram: 22°C

Day–Night Temperature Differences

  • Thar Desert: Day = 50°C, Night = 15°C
  • Andaman, Nicobar, Kerala: almost no difference between day and night temperatures

4. Rainfall Variations in India

  • Snowfall in Himalayas
  • Rain in the rest of India
  • Meghalaya: 400+ cm annually
  • Ladakh & western Rajasthan: less than 10 cm

Most rainfall comes from June to September, but Tamil Nadu coast gets rain in October–November.

General Pattern:

  • Coastal areas → Less temperature variation
  • Interior areas → Greater seasonal contrast
  • Northern plains → Rainfall decreases from east to west

These climatic differences affect food, clothing, and housing styles.

5. Climatic Controls

There are six main controls of climate:

  1. Latitude
    • Due to Earth’s curvature, temperatures decrease from equator to poles.
  2. Altitude
    • Temperature decreases with height.
    • Hills are cooler.
  3. Pressure and Wind System
    • Controls temperature and rainfall patterns.
  4. Distance from Sea (Continentality)
    • Far from sea → extreme climate
    • Near sea → moderate climate
  5. Ocean Currents
    • Warm currents = warm climate
    • Cold currents = cool climate
  6. Relief Features
    • Mountains block cold/hot winds
    • Cause rainfall on windward side
    • Leeward side remains dry

6. Factors Affecting India’s Climate

A. Latitude

  • Tropic of Cancer divides India into:
    • Tropical region (south)
    • Subtropical region (north)
  • Hence India shows characteristics of both climates.

B. Altitude

  • Himalayas (6000 m) stop cold Central Asian winds → milder winters
  • Coastal areas have low elevation (30 m)

C. Pressure and Winds

Indian climate is influenced by:

  1. Pressure & surface winds
  2. Upper air circulation
  3. Western cyclonic disturbances & tropical cyclones

Winter Condition

  • India lies in region of northeasterly winds
  • These winds are dry → bring little rain

Summer Condition

  • High pressure over the Indian Ocean
  • Low pressure over NW India
  • Winds reverse direction → Southwest Monsoon brings rain

Coriolis Force

  • Due to Earth’s rotation
  • Winds deflect:
    • Right in Northern Hemisphere
    • Left in Southern Hemisphere

7. Seasons in India

India has four main seasons:

  1. Cold Weather Season (Winter)
  2. Hot Weather Season (Summer)
  3. Advancing Monsoon (Rainy Season)
  4. Retreating Monsoon (Transition Season)

7.1 Cold Weather Season (Winter)

(Mid-November to February)

  • December & January → coldest months
  • Temperature:
    • Chennai: 24–25°C
    • Northern plains: 10–15°C
  • Days are warm, nights are cold.
  • Frost common in north; snowfall in Himalayas.

Winds

  • Northeast trade winds blow from land to sea → dry season
  • Tamil Nadu coast gets rainfall because winds blow from sea to land there.

Western Disturbances

  • Cyclonic depressions from the Mediterranean Sea
  • Bring:
    • Winter rainfall → called mahawat
    • Snowfall in Himalayas
  • Important for rabi crops

Peninsular India

  • No clear winter due to the sea’s moderating influence.

7.2 Hot Weather Season (Summer)

(March to May)

  • Sun moves north → temperature rises
  • Highest temperatures:
    • March → Deccan plateau (38°C)
    • April → Gujarat, MP (42°C)
    • May → NW India (45°C)

Low Pressure Trough

  • From Thar Desert to Patna and Chotanagpur

Important Characteristics

  • Loo: hot, dry winds in NW India
  • Dust storms: lower temperature, bring light rain
  • Kaal Baisakhi in West Bengal: violent thunderstorms
  • Mango showers in Kerala & Karnataka: help ripening mangoes

7.3 Advancing Monsoon (Rainy Season)

(June to September)

  • Low pressure over northern plains becomes strong.
  • SE trade winds cross equator → become SW Monsoon winds.
  • Bring heavy moisture → rainfall.

Rainfall Distribution

  • Western Ghats: 250+ cm
  • Mawsynram (Meghalaya): highest rainfall in the world
  • Rain decreases from east to west in Ganga valley
  • Rajasthan & Gujarat: very little rain

Breaks in Monsoon

  • Alternating wet and dry spells
  • Caused by the movement of the monsoon trough

Monsoon Uncertainty

  • Irregular arrival and withdrawal
  • Can cause:
    • Floods in some areas
    • Droughts in others

7.4 Retreating Monsoon (Transition Season)

(October – November)

  • Sun shifts southward
  • Monsoon trough becomes weak
  • SW Monsoon withdraws from northern plains by early October

Characteristics

  • Clear skies
  • Rise in temperature → October Heat
  • Days hot; nights cool
  • Land remains moist

Cyclones

  • Low pressure shifts to Bay of Bengal
  • Cyclonic depressions form over Andaman Sea
  • Affects:
    • Godavari, Krishna, Kaveri deltas
    • Sometimes Odisha, West Bengal, Bangladesh

Coromandel Coast

  • Receives most rainfall from these cyclones.

8. Distribution of Rainfall in India

  • Western coast & NE India: 400+ cm
  • Rajasthan, Gujarat, Haryana, Punjab: less than 60 cm
  • Interior Deccan & east of Sahyadris: low rainfall
  • Leh (J&K): low rainfall
  • Snowfall only in Himalayas

Variability is high in low rainfall areas → drought and flood-prone regions.

9. Monsoon as a Unifying Bond

  • Himalayas block cold winds → moderate temperatures
  • Peninsular region moderate due to sea
  • Despite variations, monsoon unifies India:
    • Agriculture depends on it
    • Rivers carry monsoon water across India
    • Festivals, farming calendar, lifestyle depend on monsoon
    • People across the country eagerly await monsoon rains

 

 

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📘 CLASS 9 GEOGRAPHY — CLIMATE (EXERCISE ANSWERS)

1. Choose the correct answer

(i) Which one of the following places receives the highest rainfall in the world?

Answer: (b) Mawsynram

(ii) The wind blowing in the northern plains in summers is known as:

Answer: (b) Loo

(iii) Monsoon arrives in India approximately in:

Answer: (c) Early June

(iv) Which one of the following characterises the cold weather season in India?

Answer: (c) Cool days and cold nights

2. Answer the following questions briefly

(i) What are the controls affecting the climate of India?

The major controls of India’s climate are:

  1. Latitude
  2. Altitude
  3. Pressure and wind system
  4. Distance from the sea (continentality)
  5. Ocean currents
  6. Relief features such as mountains

(ii) Why does India have a monsoon type of climate?

India has a monsoon type of climate due to:

  • Differential heating and cooling of land and water
  • Shift of the Inter Tropical Convergence Zone (ITCZ)
  • Presence of high pressure over the Indian Ocean
  • Tibetan Plateau heating in summer
  • Movement of the westerly and easterly jet streams
    These factors create strong seasonal reversal of winds     → monsoon.

(iii) Which part of India experiences the highest diurnal range of temperature and why?

North-western India, especially the Thar Desert and adjoining areas, experience the highest diurnal range of temperature because:

  • There is no moderating influence of the sea
  • Sand heats up quickly during the day and cools rapidly at night

(iv) Which winds account for rainfall along the Malabar coast?

The south-west monsoon winds (Arabian Sea branch) bring heavy rainfall to the Malabar coast.

(v) Define monsoons. What do you understand by “break” in monsoon?

Monsoon:
Seasonal reversal of wind direction that brings widespread rainfall in India.

Break in Monsoon:
Rainfall does not occur continuously. Rainfall occurs for a few days, then stops for a few days due to changes in monsoon trough or wind pattern. This interruption is called a break in monsoon.

(vi) Why is the monsoon considered a unifying bond?

Monsoon unifies India because:

  • Almost all regions depend on monsoon rainfall for agriculture
  • Festivals, crops, food habits, and economy revolve around monsoon timing
  • Rivers, vegetation cycles, and water availability are shaped by monsoon
    Thus, monsoon creates common climatic rhythm across India.

3. Why does rainfall decrease from east to west in Northern India?

Rainfall decreases from east to west because:

  • The Bay of Bengal branch of the monsoon moves westward.
  • As it moves, it loses moisture continuously.
    Therefore, eastern states (West Bengal, Bihar, Assam) receive more rainfall, and western regions (Punjab, Haryana, Rajasthan) receive less.

4. Give reasons

(i) Seasonal reversal of wind direction takes place over the Indian subcontinent.

Because of:

  • Differential heating of land and sea
  • High pressure over the Indian Ocean and low pressure over the landmass in summer
  • Reverse pressure conditions in winter
    This causes winds to reverse direction seasonally.

(ii) The bulk of rainfall in India is concentrated over a few months.

  • The monsoon lasts only June to September.
  • Most of India’s rainfall comes from monsoon winds.
    So rainfall is limited to these 3–4 months.

(iii) The Tamil Nadu coast receives winter rainfall.

  • During winter, north-east monsoon winds blow from land to sea.
  • These winds pick up moisture from the Bay of Bengal.
  • They hit the Tamil Nadu coast, causing rainfall.

(iv) The delta region of the eastern coast is frequently struck by cyclones.

  • The Bay of Bengal is a breeding ground for tropical cyclones.
  • Low pressure systems form easily in October–November.
  • These storms move towards the eastern coast, striking the deltas (Godavari, Krishna, Kaveri).

(v) Parts of Rajasthan, Gujarat and the leeward side of the Western Ghats are drought-prone.

  • Rajasthan and Gujarat lie in the rain shadow of the Aravalli and Western Ghats.
  • The Arabian Sea branch passes parallel to the Aravallis, giving no rain.
  • Leeward side of Western Ghats receives very little rain due to rain-shadow effect.

5. Describe the regional variations in the climatic conditions of India.

India has huge climatic variations:

Temperature Variations

  • Rajasthan: temperature may rise above 50°C
  • Drass, Leh (J&K): temperature may fall below –45°C

Rainfall Variations

  • Mawsynram: highest rainfall in the world (over 1100 cm)
  • Western Rajasthan: less than 10 cm

Seasonal Variations

  • Coastal regions: little difference between day and night temperature
  • Interior areas: high diurnal temperature range

Wind and Pressure Differences

  • Himalayas block cold winds, keeping northern plains warmer
  • Coastal regions experience sea breezes

These examples show strong regional diversity.

6. Give an account of weather conditions and characteristics of the cold season.

Cold Season (Winter): December to February

Weather Conditions

  • Temperature: Cool days and cold nights
  • Low humidity
  • Clear skies
  • Weak sunshine

Wind System

  • North-east trade winds blow
  • Western disturbances bring rain to the northern plains and snowfall to the Himalayas

Rainfall

  • Light rainfall in Punjab, Haryana, Delhi
  • Snowfall in the Himalayas

Effects

  • Good for rabi crops
  • Pleasant climate in most regions

7. Give the characteristics and effects of monsoon rainfall in India.

Characteristics

  1. Seasonal reversal of winds
  2. Concentrated rainfall (June–September)
  3. Uneven distribution
  4. Breaks and bursts
  5. Frequent floods and droughts
  6. Influenced by depressions and cyclones

Effects

  1. Essential for agriculture
  2. Determines cropping pattern
  3. Affects water resources, rivers, and dams
  4. Floods damage life and property
  5. Failure of monsoon leads to drought
  6. Affects economy and food supply

MAP SKILLS — Descriptions

(You can draw these)

(i) Areas receiving rainfall over 400 cm

  • Western Ghats (windward side)
  • Meghalaya (Mawsynram, Cherrapunji)

(ii) Areas receiving less than 20 cm

  • Western Rajasthan
  • Kutch region of Gujarat
  • Ladakh

(iii) Direction of South-West Monsoon

  • Arabian Sea branch → from southwest to northeast
  • Bay of Bengal branch → from southeast to northwest

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