CLIMATE OF INDIA

1. CLIMATE OF INDIA

2. Climatic Extremes - Temperature • 55o C • Rajasthan on a hot summer day • -50o C • Ladakh on a winter dawn

3. Climatic Extremes - Rainfall • >2500 cm • Mawsynram (Meghalaya) • <13 cm • Thar desert

4. Climatic Extremes – Annual Range of Temperatute • 3o C • Malabar Coast • 20o C • Interior India (Delhi)

5. So, What’s Common ? • The entire sub-continent receives rainfall due to Monsoon winds

6. Factors affecting Climate of India • Latitude • Physical features • Altitude • Distance from the Sea • Other minor factors

7. 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

8. 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

9. Influence of Relief – Other features • Western Ghats • Uneven rainfall in the peninsula • Aravallis • Dry climate in Rajasthan

10. Influence of Altitude • Deccan Plateau cooler than Northern Plains in summer • Snowfall in Himalayas

11. Distance from the Sea • Equable climate in coastal areas • Extreme climate in the interior

12. Other factors • Western disturbances • Winter Rainfall in Punjab • Conditions surrounding the sub-continent • Indian Ocean • Africa • Jet Streams • Not much known

13. Seasons in India • Summer • Rainy Season • Retreating Monsoon Season • Winter

14. THE INDIAN SUMMER

15. Summer Season - Dateline • March to May • Sun directly overhead on equator on March 21 • Sun directly overhead on Tropic of Cancer on June 21

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

17. The Indian Summer - Summary • Monsoon winds not drawn into India due to HP over Peninsula • Hot ‘Loo’ in northern plains • Kalbaisakhi in West Bengal • Mango Showers in Kerala

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

19. THE INDIAN MONSOON

20. Monsoon – Meaning • Refers to a seasonal wind which blows over the Indian sub-continent • Sea to land in summer • Land to sea in winter

21. Monsoon – Unique features • Brings rains to the sub-continent • Varies in strength • Uncertain and Uneven

22. 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

23. 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

24. THE INDIAN MONSOON JUNE TO SEP L P L P H P H P

25. Mechanism of Monsoons

26. 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

27. 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

28. Rainfall Distribution Map of India

29. Features of Indian Rainfall • Occurs from June to September • Distinct Rainy Season • Erratic and unpredictable • Unevenly distributed • Orographic rainfall • Cyclones and convectional rainfall

30. THE RETREATING MONSOON

31. 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’

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

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

34. 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

35. THE RETREATING MONSOON OCT AND NOV L P L P H P H P

36. WINTERS OF INDIA

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

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

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

40. 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

41. 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’

42. 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)