Editing Tamil Nadu (section)

=== Climate ===
[[File:Koppen-Geiger Map IND present.svg|thumb|Climatic zones of India]]

The region has a [[tropical climate]] and depends on monsoons for rainfall.<ref>{{cite book|last1=McKnight|first1=Tom L|last2=Hess|first2=Darrel|year=2000|chapter=Climate Zones and Types: The Köppen System|title=Physical Geography: A Landscape Appreciation|pages=[https://archive.org/details/physicalgeographmckn/page/205 205–211]|location=Upper Saddle River, NJ|publisher=Prentice Hall|isbn=978-0-130-20263-5|chapter-url=https://archive.org/details/physicalgeographmckn|url=https://archive.org/details/physicalgeographmckn/page/205}}</ref> Tamil Nadu is divided into seven agro-climatic zones: northeast, northwest, west, southern, high rainfall, high altitude hilly, and [[Kaveri]] delta.<ref>{{cite web|url=https://farmech.dac.gov.in/FarmerGuide/TN/Introduction.htm|title=Farmers Guide, introduction|publisher=[[Government of India]]|access-date=1 December 2023|archive-date=26 June 2022|archive-url=https://web.archive.org/web/20220626154923/https://farmech.dac.gov.in/FarmerGuide/TN/Introduction.htm|url-status=live}}</ref> A [[tropical savanna climate|tropical wet and dry climate]] prevails over most of the inland peninsular region except for a semi-arid [[rain shadow]] east of the Western Ghats. Winter and early summer are long dry periods with temperatures averaging above {{convert|18|°C|°F|0}}; summer is exceedingly hot with temperatures in low-lying areas exceeding {{convert|50|°C|°F|0}}; and the rainy season lasts from June to September, with annual rainfall averaging between {{convert|750|and|1500|mm|in|0|abbr=on}} across the region. Once the dry northeast monsoon begins in September, most precipitation in India falls in Tamil Nadu, leaving other states comparatively dry.<ref>{{cite news|url=https://news.bbc.co.uk/2/hi/south_asia/1994174.stm|title=India's heatwave tragedy|work=[[BBC News]]|date=17 May 2002|access-date=20 March 2016|archive-date=31 March 2024|archive-url=https://web.archive.org/web/20240331152820/http://news.bbc.co.uk/2/hi/south_asia/1994174.stm|url-status=live}}</ref> 

[[File:India_southwest_summer_monsoon_onset_map_en.svg|thumb|left|Tamil Nadu gets most of the rains from the [[monsoon]]]]

A [[hot semi-arid climate]] predominates in the land east of the Western Ghats which includes inland south and south central parts of the state and gets between {{convert|400|and|750|mm|1}} of rainfall annually, with hot summers and dry winters with temperatures around {{convert|20|–|24|C|F}}. The months between March and May are hot and dry, with mean monthly temperatures hovering around {{convert|32|C|F}}, with {{convert|320|mm|in|0}} precipitation. Without artificial irrigation, this region is not suitable for agriculture.<ref>{{cite book|last=Caviedes|first=C. N.|title=El Niño in History: Storming Through the Ages|edition=1st|publisher=University Press of Florida|date=18 September 2001|isbn=978-0-813-02099-0}}</ref>

The [[southwest monsoon]] from June to September accounts for most of the rainfall in the west of the region. The Arabian Sea branch of the southwest monsoon hits the Western Ghats from Kerala and moves northward along the [[Konkan coast]], with precipitation on the western region of the state.<ref>{{cite web|url=https://wgbis.ces.iisc.ac.in/biodiversity/sahyadri/wgbis_info/climate.htm|title=Climate of Western Ghats|publisher=Indian Institute of Science|access-date=1 December 2023|archive-date=21 May 2024|archive-url=https://web.archive.org/web/20240521124321/https://wgbis.ces.iisc.ac.in/biodiversity/sahyadri/wgbis_info/climate.htm|url-status=live}}</ref> The lofty Western Ghats prevent the winds from reaching the Deccan Plateau; hence, the leeward region (the region deprived of winds) receives very little rainfall.<ref>{{NatGeo ecoregion|id=im0209|name=South Deccan Plateau dry deciduous forests|access-date=5 January 2005}}</ref><ref>{{WWF ecoregion|id=im0209|name=South Deccan Plateau dry deciduous forests|access-date=5 January 2005}}</ref> The Bay of Bengal branch of the southwest monsoon heads toward northeast India, picking up moisture from the Bay of Bengal. The Coramandel coast does not receive much rainfall from the southwest monsoon, due to the shape of the land.<ref>{{cite web|url=https://www.britannica.com/science/Indian-monsoon|title=Indian monsoon|publisher=Britannica|access-date=1 December 2023|archive-date=1 August 2016|archive-url=https://web.archive.org/web/20160801140005/https://www.britannica.com/science/Indian-monsoon|url-status=live}}</ref> The northern and eastern parts of Tamil Nadu receive most of their rains from the [[northeast monsoon]].<ref>{{cite web|url=https://www.imdchennai.gov.in/northeast_monsoon.htm|title=North East Monsoon|publisher=[[Indian Meteorological Department]]|access-date=1 January 2016|archive-date=29 December 2015|archive-url=https://web.archive.org/web/20151229133725/http://www.imdchennai.gov.in/northeast_monsoon.htm|url-status=live}}</ref> 

The northeast monsoon takes place from November to early March, when the surface [[high-pressure system]] is strongest.<ref>{{cite book|title=Climatology|first1=Robert V.|last1=Rohli|first2=Anthony J.|last2=Vega|page=204|publisher=Jones & Bartlett Publishers|year=2007|isbn=978-0-763-73828-0}}</ref> The [[North Indian Ocean tropical cyclone]]s occur throughout the year in the Bay of Bengal and the Arabian Sea, bringing devastating winds and heavy rainfall.<ref>{{cite report|url=https://rsmcnewdelhi.imd.gov.in/uploads/climatology/annualcd.pdf|title=Annual frequency of cyclonic disturbances over the Bay of Bengal (BOB), Arabian Sea (AS) and land surface of India|publisher=[[India Meteorological Department]]|access-date=1 January 2023|archive-date=23 June 2022|archive-url=https://web.archive.org/web/20220623160147/https://rsmcnewdelhi.imd.gov.in/uploads/climatology/annualcd.pdf|url-status=live}}</ref><ref>{{cite web|url=https://oceanservice.noaa.gov/facts/cyclone.html|title=The only difference between a hurricane, a cyclone, and a typhoon is the location where the storm occurs|publisher=NOAA|access-date=1 October 2014|archive-date=11 November 2019|archive-url=https://web.archive.org/web/20191111165427/https://oceanservice.noaa.gov/facts/cyclone.html|url-status=live}}</ref> The annual rainfall of the state is about {{convert|945|mm|in|abbr=on}} of which 48 per cent is through the northeast monsoon, and 52 per cent through the southwest monsoon. The state has only 3% of the water resources nationally and is entirely dependent on rains for recharging its water resources. Monsoon failures lead to acute [[water scarcity]] and [[2016–17 Drought in Tamil Nadu|severe drought]].<ref>{{cite report|title=Assessment of Recent Droughts in Tamil Nadu|url=https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1057&context=droughtnetnews|publisher=Water Technology Centre, Indian Agricultural Research Institute|date=October 1995|access-date=1 December 2023|archive-date=23 December 2023|archive-url=https://web.archive.org/web/20231223140326/https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1057&context=droughtnetnews|url-status=live}}</ref><ref>{{cite report|url=https://dolr.gov.in/sites/default/files/TAMILNADU%20STATE%20PERSPECTIVE%20%26%20STRATEGIC%20PLAN.pdf|title=Strategic plan, Tamil Nadu perspective|publisher=[[Government of India]]|access-date=1 December 2023|page=3|archive-date=9 March 2024|archive-url=https://web.archive.org/web/20240309100229/https://dolr.gov.in/sites/default/files/TAMILNADU%20STATE%20PERSPECTIVE%20%26%20STRATEGIC%20PLAN.pdf|url-status=live}}</ref>