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
- Temperature
- Atmospheric
pressure
- Wind
- Humidity
- 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:
- Latitude
- Due
to Earth’s curvature, temperatures decrease from equator to poles.
- Altitude
- Temperature
decreases with height.
- Hills
are cooler.
- Pressure and
Wind System
- Controls
temperature and rainfall patterns.
- Distance from
Sea (Continentality)
- Far
from sea →
extreme climate
- Near
sea →
moderate climate
- Ocean Currents
- Warm
currents = warm climate
- Cold
currents = cool climate
- 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:
- Pressure &
surface winds
- Upper air
circulation
- 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:
- Cold Weather
Season (Winter)
- Hot Weather
Season (Summer)
- Advancing
Monsoon (Rainy Season)
- 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:
- Latitude
- Altitude
- Pressure and
wind system
- Distance from
the sea (continentality)
- Ocean currents
- 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
- Seasonal
reversal of winds
- Concentrated
rainfall (June–September)
- Uneven
distribution
- Breaks and
bursts
- Frequent floods
and droughts
- Influenced
by depressions and cyclones
Effects
- Essential for
agriculture
- Determines
cropping pattern
- Affects water
resources, rivers, and dams
- Floods damage
life and property
- Failure of
monsoon leads to drought
- 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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