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CLIMATE OF

INDIA

2CLIMATIC EXTREMES - TEMPERATURE

•55o C• Rajasthan on a hot summer day

•-50o C• Ladakh on a winter dawn

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CLIMATIC EXTREMES - RAINFALL

•>2500 cm• Mawsynram (Meghalaya)

•<13 cm• Thar desert

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CLIMATIC EXTREMES – ANNUAL RANGE OF

TEMPERATUTE

•3o C • Malabar Coast

•20o C• Interior India (Delhi)

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SO, WHAT’S COMMON ?• The entire sub-continent receives rainfall due to

Monsoon winds

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FACTORS AFFECTING CLIMATE OF INDIA

1. Latitude2. Physical features3. Altitude4. Distance from the Sea5. Other minor factors

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INFLUENCE OF LATITUDE

• Tropic of Cancer passes through India• Northern half – Temperate• Southern Half – Torrid

• Yet the sub-continent is said to have a sub-tropical climate!!!

• No striking difference of temperature• Seasonal rainfall due to monsoons

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INFLUENCE OF RELIEF - HIMALAYAS

• Himalayas• Stop cold winds from north• Help to create HT-LP regime• Pull monsoons• Force monsoons to shed moisture in India

• Arakan Yoma Range• Deflect the monsoons into India

9INFLUENCE OF RELIEF – OTHER FEATURES

• Western Ghats• Uneven rainfall in the peninsula

• Aravallis• Dry climate in Rajasthan

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INFLUENCE OF ALTITUDE

• Deccan Plateau cooler than Northern Plains in summer

• Snowfall in Himalayas

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DISTANCE FROM THE SEA

• Equable climate in coastal areas• Extreme climate in the interior

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OTHER FACTORS• Western disturbances

• Winter Rainfall in Punjab• Conditions surrounding the sub-continent

• Indian Ocean• Africa

• Jet Streams• Not much known

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Seasons in India Summer Rainy Season Retreating Monsoon Season Winter

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THE INDIAN SUMMER

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Summer Season - DatelineMarch to MaySun directly overhead on equator on

March 21Sun directly overhead on Tropic of Cancer

on June 21

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The Indian Summer - SummaryFrom March to May (Movement of sun

from Equator to Tropic of Cancer)High temperature, low pressure over the

northern plainsLow temperature, slightly high pressure

over the Peninsular PlateauHigh pressure over Indian Ocean

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The Indian Summer - SummaryMonsoon winds not drawn into India due

to HP over PeninsulaHot ‘Loo’ in northern plainsKalbaisakhi in West BengalMango Showers in Kerala

THE INDIAN SUMMER

March to May

L P

H P

H P H PMANGO SHOWER

KALBAISAKHI

LOO

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THE INDIAN MONSOON

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MONSOON – MEANING• Refers to a seasonal wind which blows over the

Indian sub-continent• Sea to land in summer• Land to sea in winter

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MONSOON – UNIQUE FEATURES

• Brings rains to the sub-continent• Varies in strength• Uncertain and Uneven

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MONSOON - TIMELINE• June to September• Sun moves from Tropic of Cancer to

Equator• Causes LP in peninsular India

• By August, monsoon spreads all over India

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MONSOON – ARRIVAL TIMES

• Monsoon arrival dates• Western Ghats, NE states – 15th June• North-western India, Eastern Ghats – 1st July• Northern Plains, Central India – 15th July

• Kanyakumari is the first place to receive rainfall

• Kerala is the first state to receive rainfall

THE INDIAN MONSOON

JUNE TO SEP

L P

L P

H P

H P

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MECHANISM OF MONSOONS

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DISTRIBUTION OF RAINFALL

• Areas of Heavy Rainfall (>200 cm)• Windward Side of Western Ghats• Eastern Himalayas• West Bengal

• Areas of Moderately heavy rainfall (100-200 cm)• Deccan Plateau• Middle Ganga Valley• Orissa

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DISTRIBUTION OF RAINFALL

• Areas of Moderate Rainfall (50-100 cm)• Eastern Ghats• Upper Ganga VAlley• Gujarat, Punjab, Rajasthan

• Areas of Scanty Rainfall (<50 cm)• Western Rajasthan• Northern J & K• Kutch

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Rainfall Distribution Map

of India

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FEATURES OF INDIAN RAINFALL

• Occurs from June to September• Distinct Rainy Season• Erratic and unpredictable• Unevenly distributed• Orographic rainfall• Cyclones and convectional rainfall

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THE RETREATING MONSOON

31Retreating Monsoon - Meaning

►Strength of monsoon decreases►Extent to which monsoons were able

to reach from June to September decreases

►Direction remains the same►Also called ‘Retreating SW Monsoon’

32Retreating Monsoon - Causes►Sun moves from Equator towards

Tropic of Capricorn►Temperatures drop►LP replaced by HP

33Retreating Monsoon - Dateline

►October and November►Monsoon withdrawal dates

Northern Plains – 15th September Western Ghats – 1st October Kolkata – 15th October Kerala – 15th November

34Retreating Monsoon - Summary

►Monsoons decrease in intensity►LP gradually replaced by HP►In the northern plains, it is

oppressively hot – a condition called ‘October Heat’

►Cyclones hit east coast and Bangladesh

►Kerala last state from where monsoons withdraw

THE RETREATING MONSOON

OCT AND NOV

L P

L P

H P H P

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WINTERS OF INDIA

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The Indian Winter - Dateline November to February Sun descends towards Tropic of Capricorn

THE INDIAN WINTER

DEC TO FEB

HP

H P

L P L P

NORTH EAST MONSOON

WESTERN DISTURBANCES

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WINDS IN WINTER

• Although India lies in Trade Wind Belt,• Himalayas & Arakan Yoma Ranges do not

allow them to come to India

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WINDS IN WINTER

• HP over Land, LP over Sea• Winds move from Land to Sea• Deflected due to Coriolis Effect• Blow from NE to SW• Called NE monsoon winds• Direction coincides with Trade Winds• SW Monsoon winds ‘reverse’ in direction

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Summary of Indian Winter Cool and Pleasant December to February Sun shines in the Southern Hemisphere HP over land; LP over Sea Winds move from Land to Sea (North East

Monsoons) – a phenomenon called ‘Reversal of Winds’

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Summary of Indian Winter Western Disturbances come to India Cause cyclonic rainfall in Punjab Move along the foothills of the Himalayas into

the Bay of Bengal NE Monsoons joined by Western Disturbances

cause rainfall in Tamil Nadu (Palni, Javadi and Shevaroy hills)