Title current - 19.pdf ✅

www.iaritoppers.in Whatsapp : +91-9694095242 Page | 1 Indian Meteorological Department  Indian Meteorological Department was established in the year 1875 with its headquarters at Culcutta.  The headquarter was shifted to Shimla in 1905, to Pune in 1928 and then to Delhi in 1944.  Annual Rainfall (2022) : 1257 mm.  Long period average (LPA) annual rainfall in India is around : 1160 mm  Average Annual Precipitation : 3,880 BCM  Gujarat region receives maximum rainfall i.e. 96% of it’s annual rainfall in southwest monsoon season while Tamil Nadu receives maximum rainfall i.e 48% of annual rainfall in post-monsoon season (October-December) followed by 36% of annual rainfall in southwest monsoon season.  South West Monsoon rainfall of India contributes 74.9% of Annual Rainfall. June, July, August, and September contribute 19.1%, 32.3%, 29.4% & 19.3% respectively to total SW monsoon rainfall. Meteorological seasons over India are:  Winter Season: January – February  Pre-Monsoon Season: March – May  Southwest Monsoon Season: June - September  Post Monsoon Season: October - December Normal date for Onset of southwest monsoon: South Andaman Sea 20 May Kerala 1 June Mumbai 10 June New Delhi 29 June Entire country 15 July Withdrawal of southwest monsoon Normal date of withdrawal from extreme west Rajasthan is 15 September. Current Affairs Part-19
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 2 Northeast Monsoon:  With the withdrawal of the southwest monsoon from the northern and central India and the northern parts of the Peninsula by the first half of the October, the wind pattern rapidly changes from southwesterly to northeasterly and hence the term ”Northeast Monsoon” is used to describe the period October to December.  This is the major period of rainfall in south peninsula. In Tamil Nadu, this is the main rainy season, accounting for nearly 60 % of annual rainfall in the coastal districts. Long Period Average (LPA):  LPA of rainfall is the rainfall recorded over a particular region for a given interval (like month or season) average over a long period of years.  Current LPA of all India south west monsoon rainfall based on the average rainfall over the period 1971 -2020 is 87 cm. (868.6 MM )  The LPA uses a 50-year average because annual rainfall can be highly variable.  Monsoon rainfall in 2022: 108% of the long-period average (LPA)  Monsoon rainfall in 2021: 99% of the long-period average (LPA) Updated Rainfall Normal based on data of 1971-2020 Annual Normal Rainfall over India based on 1971-2020 and 1961-2010: Period 1961-2010 1971-2020 Annual Rainfall (mm) 1176.9 1160.1 Seasonal Normal Rainfall over India based on 1971-2020: 1971-2020 Season Rainfall (mm) % of Annual Rainfall (mm) Winter (JF) 39.8 3.4% Pre monsoon (MAM) 130.6 11.3% SW Monsoon (JJAS) 868.6 74.9
www.iaritoppers.in Whatsapp : +91-9694095242 Page | 3 Post Monsoon (OND) 121.0 10.4 Categories: IMD maintains five rainfall distribution categories on an all-India scale which are –  Excess: If the rainfall is more than 110 % of this LPA.  Above Normal: If the rainfall is between 104 and 110 % of this LPA.  Normal: If the rainfall is between 96 and 104 % of this LPA.  Below Normal: If the rainfall is between 90 and 96 % of this LPA.  Deficient: If the rainfall is less than 90 % of this LPA. Categories of rainfall used to describe realised rainfall (Weekly/Seasonal):  Large Excess: ≥60%  Excess: 20 to 59%  Normal : -19% to +19%  Deficient : -59% to -20%  Large Deficient: -99% to -60% Meteorological Drought:  According to India Meteorological Department, meteorological drought over an area is defined as a situation when the seasonal rainfall received over the area is less than 75% of its long term average value. It is further classified as "moderate drought" if the rainfall deficit is between 26-50% and "severe drought” when the deficit exceeds 50% of the normal. Hydrological Drought:  Hydrological Drought can be defined as a period during which the stream flows are inadequate to supply established use of water under a given water management system.