CLIMATE OF INDIA 1

CLIMATIC EXTREMES - TEMPERATURE 55 o C Rajasthan on a hot summer day -50 o C Ladakh on a winter dawn 2

CLIMATIC EXTREMES - RAINFALL >2500 cm Mawsynram (Meghalaya) <13 cm Thar desert 3

CLIMATIC EXTREMES – ANNUAL RANGE OF TEMPERATUTE 3 o C Malabar Coast 20 o C Interior India (Delhi) 4

SO, WHAT’S COMMON ? The entire sub-continent receives rainfall due to Monsoon winds 5

FACTORS AFFECTING CLIMATE OF INDIA 1.Latitude 2.Physical features 3.Altitude 4.Distance from the Sea 5.Other minor factors 6

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 7

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 8

INFLUENCE OF RELIEF – OTHER FEATURES Western Ghats Uneven rainfall in the peninsula Aravallis Dry climate in Rajasthan 9

INFLUENCE OF ALTITUDE Deccan Plateau cooler than Northern Plains in summer Snowfall in Himalayas 10

DISTANCE FROM THE SEA Equable climate in coastal areas Extreme climate in the interior 11

OTHER FACTORS Western disturbances Winter Rainfall in Punjab Conditions surrounding the sub-continent Indian Ocean Africa Jet Streams Not much known 12

Seasons in India 13

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March to May March to May Sun directly overhead on equator on March 21 Sun directly overhead on equator on March 21 Sun directly overhead on Tropic of Cancer on June 21 Sun directly overhead on Tropic of Cancer on June 21 15

From March to May (Movement of sun from Equator to Tropic of Cancer) From March to May (Movement of sun from Equator to Tropic of Cancer) High temperature, low pressure over the northern plains High temperature, low pressure over the northern plains Low temperature, slightly high pressure over the Peninsular Plateau Low temperature, slightly high pressure over the Peninsular Plateau High pressure over Indian Ocean High pressure over Indian Ocean 16

Monsoon winds not drawn into India due to HP over Peninsula Monsoon winds not drawn into India due to HP over Peninsula Hot ‘Loo’ in northern plains Hot ‘Loo’ in northern plains Kalbaisakhi in West Bengal Kalbaisakhi in West Bengal Mango Showers in Kerala Mango Showers in Kerala 17

THE INDIAN SUMMER March to May L P H P MANGO SHOWER KALBAISAKHI LOO

THE INDIAN MONSOON 19

MONSOON – MEANING Refers to a seasonal wind which blows over the Indian sub-continent Sea to land in summer Land to sea in winter 20

MONSOON – UNIQUE FEATURES Brings rains to the sub-continent Varies in strength Uncertain and Uneven 21

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 22

MONSOON – ARRIVAL TIMES Monsoon arrival dates Western Ghats, NE states – 15 th June North-western India, Eastern Ghats – 1 st July Northern Plains, Central India – 15 th July Kanyakumari is the first place to receive rainfall Kerala is the first state to receive rainfall 23

THE INDIAN MONSOON JUNE TO SEP L P H P

MECHANISM OF MONSOONS 25

DISTRIBUTION OF RAINFALL Areas of Heavy Rainfall (>200 cm) Windward Side of Western Ghats Windward Side of Western Ghats Eastern Himalayas Eastern Himalayas West Bengal West Bengal Areas of Moderately heavy rainfall ( cm) Deccan Plateau Deccan Plateau Middle Ganga Valley Middle Ganga Valley Orissa Orissa 26

DISTRIBUTION OF RAINFALL Areas of Moderate Rainfall ( cm) Eastern Ghats Eastern Ghats Upper Ganga VAlley Upper Ganga VAlley Gujarat, Punjab, Rajasthan Gujarat, Punjab, Rajasthan Areas of Scanty Rainfall (<50 cm) Western Rajasthan Western Rajasthan Northern J & K Northern J & K Kutch Kutch 27

Rainfall Distribution Map of India 28

FEATURES OF INDIAN RAINFALL Occurs from June to September Distinct Rainy Season Erratic and unpredictable Unevenly distributed Orographic rainfall Cyclones and convectional rainfall 29

THE RETREATING MONSOON 30

Retreating 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’ 31

Retreating Monsoon - Causes ► Sun moves from Equator towards Tropic of Capricorn ► Temperatures drop ► LP replaced by HP 32

Retreating Monsoon - Dateline ► October and November ► Monsoon withdrawal dates  Northern Plains – 15 th September  Western Ghats – 1 st October  Kolkata – 15 th October  Kerala – 15 th November 33

Retreating 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 34

THE RETREATING MONSOON OCT AND NOV L P H P

WINTERS OF INDIA 36

The Indian Winter - Dateline November to February November to February Sun descends towards Tropic of Capricorn Sun descends towards Tropic of Capricorn 37

THE INDIAN WINTER DEC TO FEB HP L P NORTH EAST MONSOON WESTERN DISTURBANCES

WINDS IN WINTER Although India lies in Trade Wind Belt, Himalayas & Arakan Yoma Ranges do not allow them to come to India 39

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 40

Summary of Indian Winter Cool and Pleasant Cool and Pleasant December to February December to February Sun shines in the Southern Hemisphere Sun shines in the Southern Hemisphere HP over land; LP over Sea HP over land; LP over Sea Winds move from Land to Sea (North East Monsoons) – a phenomenon called ‘Reversal of Winds’ Winds move from Land to Sea (North East Monsoons) – a phenomenon called ‘Reversal of Winds’ 41

Summary of Indian Winter Western Disturbances come to India Western Disturbances come to India Cause cyclonic rainfall in Punjab Cause cyclonic rainfall in Punjab Move along the foothills of the Himalayas into the Bay of Bengal 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) NE Monsoons joined by Western Disturbances cause rainfall in Tamil Nadu (Palni, Javadi and Shevaroy hills) 42