Study this in the app →

English · हिन्दी · తెలుగు · தமிழ் · മലയാളം · मराठी · ಕನ್ನಡ

Rainfall, variability and forecasting

मराठीत स्पष्टीकरण

Climate of India · Part 3 / 3 · Fact-checked on · how we check

Written with AI from the sources listed at the bottom of this page, then fact-checked by a separate AI.

Where rain falls in India and why; the coefficient of variation; droughts and floods; IMD's definitions of heat waves, cold waves and cloudbursts; Köppen's climatic regions of India; the monsoon as a unifying influence; and how IMD forecasts the monsoon against the long period average.

Each idea is explained first in Marathi (मराठी), ending with the English and Hindi exam terms, followed by the same point in exam English. UPSC Prelims is in English or Hindi, so understand it in Marathi and revise it in English.

भाग 1 आणि 2 मध्ये मान्सून कसा चालतो आणि ऋतू कसे घडवतो ते पाहिले. आता परिणाम: कुठे किती पाऊस, तो किती भरवशाचा, कमी किंवा जास्त पडला तर काय, हवामान प्रदेश, IMD चे अंदाज. पेरणी कधी करायची याचा विचार करणारा शेतकरी ते धरणे सांभाळणारे शहरी अधिकारी, सगळे एकच पावसाचे आकडे पाहतात — घरखर्च पगारावर अवलंबून असतो तसे पिके आणि पाणी मान्सूनवर. (→ English: monsoon; rainfall · हिन्दी: मानसून; वर्षा)

In exam EnglishParts 1 and 2 showed how the monsoon works and how it shapes the seasons. This last part looks at the result on the ground: how much rain different parts of India receive, how dependable that rain is, what happens when it fails or comes in excess, how India's climates can be grouped, and how the India Meteorological Department forecasts the season. These are practical questions. A farmer choosing a sowing date, an engineer planning a city's water and an official handling food stocks all depend on the same rainfall figures, because so much still hangs on the monsoon: how big the harvest is, what villages earn, and how much water is saved for the dry season.

देशाच्या सरासरीमागे मोठे फरक दडलेले आहेत. वर्षाला 200 सेंमीहून अधिक पाऊस तीन ठिकाणी: पश्चिम किनारा–पश्चिम घाटाचा वाऱ्याकडचा उतार, मेघालय–ईशान्य भारत, पूर्व हिमालयाच्या पायथ्याचा पट्टा. तिन्हीकडे प्रतिरोध पर्जन्य — दमट हवेला डोंगर चढावा लागतो आणि पिळलेल्या कापडासारखे पाणी सुटते. मॉसिनराम, चेरापुंजी पृथ्वीवरील सर्वाधिक ओल्या ठिकाणांत. 100–200 सेंमी: मध्य व खालचे गंगेचे मैदान, ओडिशा, छत्तीसगड, पूर्व द्वीपकल्प, दक्षिण गुजरात — पावसाच्या पाण्यावरच भात पिकणारे प्रदेश. (→ English: orographic rainfall; areas of heavy rainfall · हिन्दी: पर्वतीय वर्षा; भारी वर्षा के क्षेत्र)

In exam EnglishThe national average hides huge differences from place to place. Annual rainfall tops 200 cm in three kinds of area: the west coast and the windward slopes of the Western Ghats; the hills of Meghalaya and much of the north-east; and the sub-Himalayan belt of the east, including northern West Bengal. All three receive orographic rainfall where moist monsoon winds run into high ground and are forced to rise. On the southern face of the Khasi hills, Mawsynram and Cherrapunji (Sohra) record some of the highest yearly rainfall anywhere on Earth. A moderate 100 to 200 cm falls over most of the eastern half of the country: the middle and lower Ganga plain, Odisha, Chhattisgarh, the eastern Peninsula and the southern part of Gujarat. These are the areas where rice can usually be grown on rainwater alone.

दुसऱ्या टोकाला वर्षाला 50 सेंमीपेक्षा कमी: पश्चिम राजस्थान, गुजरातचा कच्छ, लडाख. पश्चिम राजस्थानवर कोणतीच शाखा वर चढत नाही, आणि तो उपसागर शाखेच्या प्रवासाच्या शेवटी — पंक्तीच्या शेवटी बसलेल्याला भात उरत नाही तसे. लडाख हिमालयाच्या भिंतीमागचे शीत वाळवंट; थोडाफार ओलावाही बर्फ म्हणून पडतो. 50–100 सेंमी: घाटाच्या पूर्वेचा दख्खनचा अंतर्भाग — पर्जन्यछायेचा प्रदेश — पूर्व राजस्थान, पंजाब, हरियाणा, उत्तर गुजरात. नियम: द्वीपकल्पात किनाऱ्याकडून आत, उत्तरेकडील मैदानात पूर्वेकडून पश्चिमेकडे पाऊस कमी होतो. (→ English: cold desert; rain-shadow area; areas of low rainfall · हिन्दी: शीत मरुस्थल; वृष्टि छाया क्षेत्र; कम वर्षा के क्षेत्र)

In exam EnglishAt the other extreme, less than 50 cm a year falls over western Rajasthan, the Kachchh region of Gujarat and Ladakh. Two things keep western Rajasthan dry: there are no mountains there to push the monsoon air upward, and the Bay of Bengal current reaches it only at the very end of its journey, when little moisture is left. Ladakh is a cold desert, walled off from the monsoon by the Himalaya, where much of the scanty moisture falls as snow. A belt of 50 to 100 cm covers the interior of the Peninsula east of the Western Ghats, where the Deccan lies in the rain-shadow area, together with eastern Rajasthan, Punjab, Haryana and northern Gujarat. The overall picture follows two simple trends: rainfall in the Peninsula falls away from the coasts towards the interior, and in the north it falls as one travels westward across the plains.

पाऊस किती पडतो एवढेच नाही, तर तो किती भरवशाचा आहे हेही महत्त्वाचे. हे विचलन गुणांकाने मोजतात: वार्षिक पावसाच्या प्रमाण विचलनाला सरासरीने भागून टक्क्यांत. कमी असेल तर दरवर्षी जवळजवळ सारखा; जास्त असेल तर चढउतार. पगारदाराला दर महिन्याला तेवढेच, रोजंदारीवाल्याला कधी काम, कधी नाही — तसे. ओल्या प्रदेशांत (पश्चिम किनारा, ईशान्य) 25% पेक्षा कमी, कोरड्या प्रदेशांत (पश्चिम राजस्थान, कच्छ, लडाख) 50% पेक्षा जास्त. म्हणजे जिथे दुष्काळ सोसवत नाही तिथेच तो जास्त. एका हंगामातही उशिरा आगमन, मोठा खंड, लवकर माघार असू शकते. (→ English: coefficient of variation; variability of rainfall · हिन्दी: विचरण गुणांक; वर्षा की परिवर्तनशीलता)

In exam EnglishThe amount of rain matters, but so does how dependable it is. The usual yardstick is the coefficient of variation: the standard deviation of yearly rainfall shown as a percentage of the average rainfall. A low value means the rain is much the same from year to year; a high value means it swings widely. In India the two measures pull in opposite directions. The coefficient stays below roughly 25 per cent in the rain-rich west coast, Western Ghats, north-east and eastern plains, while dry regions such as western Rajasthan, Kachchh and Ladakh have values above 50 per cent. Put simply, a bad monsoon is most likely exactly where people are least able to cope with one. Variability also works within a season, through a late onset, a long break or an early withdrawal.

मान्सून कोसळला की दुष्काळ. एखाद्या भागात सामान्यपेक्षा 25% हून अधिक पाऊस कमी पडला तर IMD त्याला हवामानशास्त्रीय दुष्काळ म्हणते; 50% हून अधिक तूट गंभीर. ती तूट जमिनीतला ओलावा, पिके यांच्यापर्यंत पोहोचली की कृषी दुष्काळ; नद्या, धरणे, भूजलापर्यंत पोहोचली की जलशास्त्रीय दुष्काळ. पश्चिम राजस्थान, गुजरात आणि मराठवाड्यासारखे महाराष्ट्र–कर्नाटक–तेलंगणा–आंध्रचे पर्जन्यछायेचे अंतर्भाग सर्वाधिक धोक्यात. 2002, 2009, 2014–15 च्या तुटीच्या वर्षांत उत्पादन घटले, भाव वाढले. शेतीचा मोठा भाग अजूनही पावसावर अवलंबून असल्याने फटका गावापलीकडे जातो. (→ English: drought; meteorological drought · हिन्दी: सूखा; मौसमी सूखा)

In exam EnglishWhen the monsoon fails, drought follows. IMD treats an area as having a meteorological drought when its rainfall falls more than 25 per cent short of normal, and a shortfall of more than 50 per cent counts as severe. Agricultural and hydrological drought follow when the shortage reaches soil moisture and crops, and then rivers, reservoirs and groundwater. The areas most prone to drought lie in the low-rainfall, high-variability belts: western Rajasthan and Gujarat, and the rain-shadow interiors of Maharashtra, Karnataka, Telangana and Andhra Pradesh. Poor monsoons across the country, as in 2002 and 2009 and in two weak years running, 2014 and 2015, cut farm output and pushed up food prices, and several of these came in El Niño years. Because a large share of India's farmland still depends on rain rather than irrigation, a failed monsoon reaches well beyond the village.

जास्त पाऊसही कमी पावसाइतकाच घातक. पाणी पटकन वाहून न जाणाऱ्या पाणलोटांवर मुसळधार पाऊस पडला की पूर; ब्रह्मपुत्रा, गंगेच्या मैदानात नद्या गाळ वाहतात, पात्र बदलतात, काठ ओलांडतात — आसाम, बिहार जवळजवळ दरवर्षी. चक्रीवादळ धडकले की ओडिशा, आंध्र, तमिळनाडूच्या किनाऱ्यावर पूर; मुंबई, चेन्नईसारख्या शहरांत नीट निचरा नसलेल्या काँक्रीटच्या जमिनीवर अतिवृष्टी झाली तेव्हा. 1980 मध्ये राष्ट्रीय बाढ आयोगाने सुमारे 4 कोटी हेक्टर पूरप्रवण असल्याचा अंदाज केला. एकाच हंगामात एका राज्यात पूर, दुसऱ्यात दुष्काळ — म्हणून आकडे प्रदेशनिहाय वाचतात. (→ English: floods; flood-prone area · हिन्दी: बाढ़; बाढ़-प्रवण क्षेत्र)

In exam EnglishToo much rain is as damaging as too little. Floods come when heavy monsoon rain falls on catchments that cannot drain it fast enough, and they are worst in the Brahmaputra and Ganga plains, where rivers carry heavy loads of silt, shift their courses and spill over low banks; Assam and Bihar suffer almost every year. Coastal Odisha, Andhra Pradesh and Tamil Nadu flood when cyclones strike, and large cities such as Mumbai and Chennai have flooded when extreme rain fell on built-up land with poor drainage. In 1980 the Rashtriya Barh Ayog (National Flood Commission) put the flood-prone area of India at roughly 40 million hectares. Because the same season can bring floods to one state and drought to another, rainfall statistics are always read region by region, not only as a national total.

इशाऱ्याचा अर्थ सगळीकडे एकच असावा म्हणून IMD टोकाच्या स्थितींच्या व्याख्या देते. मैदानात कमाल तापमान किमान 40°C आणि सामान्यपेक्षा 4.5°C किंवा अधिक असेल, किंवा 45°C गाठले तर उष्णतेची लाट; डोंगरी ठिकाणांसाठी 30°C. किमान तापमान 10°C किंवा कमी आणि सामान्यपेक्षा बरेच खाली असेल, किंवा 4°C पर्यंत घसरले तर थंडीची लाट. उष्णतेच्या लाटा मार्च–जूनमध्ये वायव्य, मध्य भारत आणि तेलंगणा–आंध्रच्या अंतर्भागात; थंडीच्या लाटा डिसेंबर–फेब्रुवारीत उत्तरेत. ढगफुटी म्हणजे लहान भागात तासाभरात सुमारे 100 मिमी किंवा जास्त — बादली उपडी केल्यासारखा; हिमालयाच्या उतारांवर अचानक पूर आणि भूस्खलन. (→ English: heat wave; cold wave; cloudburst · हिन्दी: उष्ण लहर; शीत लहर; बादल फटना)

In exam EnglishIMD also defines extremes of temperature and rain, so that a warning means the same thing everywhere. For the plains, IMD's heat-wave test has two routes: a maximum of 40°C or more that is also at least 4.5°C above normal, or an actual maximum of 45°C or more regardless of the normal; for hill stations the 40°C floor becomes 30°C. A cold wave on the plains is declared when the minimum temperature is 10°C or lower and well below normal, or when it drops to 4°C or lower. Heat waves are most common from March to June over the north-west, central India and the interior of Telangana and Andhra Pradesh, while cold waves strike the north between December and February. A cloudburst is an extreme local downpour of about 100 mm or more in an hour over a small area; it is typical of Himalayan slopes, where it sets off flash floods and landslides.

या विविधतेला क्रम देतात ते हवामान प्रदेश. कोपेन हवामान वर्गीकरण मासिक तापमान आणि पाऊस पाहून देशाचे काही प्रकार करते — रेल्वेच्या डब्यांना S1, B2 असा कोड असतो तसा, प्रत्येक प्रकाराला अक्षरांचा कोड. मोठे अक्षर: A वर्षभर उष्ण उष्णकटिबंधीय, B कोरडे, C थंड ऋतू असलेले उबदार, D कडक हिवाळा, E सर्वात थंड उंच प्रदेश. लहान अक्षर: 'w' कोरडा हिवाळा, 's' कोरडा उन्हाळा. द्वीपकल्पाचा बहुतेक भाग Aw; थंड महिन्यांत पाऊस मिळणारा कोरोमंडल किनारा As. (→ English: Köppen climate classification; climatic regions · हिन्दी: कोपेन जलवायु वर्गीकरण; जलवायु प्रदेश)

In exam EnglishClimatic regions bring order to this variety. The Köppen climate classification, applied to India, uses monthly temperature and rainfall to sort the country into a few types, each written as a short code of letters. The opening capital letter names the broad group: A means tropical and warm all year, B dry, C warm with a cool season, D cold-wintered, and E the coldest highland climates. Small letters add the season of rain or drought, such as 'w' for a dry winter and 's' for a dry summer. So most of the Peninsula is Aw, a tropical savanna with a long dry season, while the Coromandel coast, which gets much of its rain in the cooler months, is As. The table below lists the main types and where they occur.
Main Köppen climate types of India
CodeTypeWhere in India
AmwMonsoon climate with a short dry spellWest coast south of about Goa
AsTropical, with the dry season in summerCoromandel coast of Tamil Nadu
AwTropical savanna with a long dry winterMost of the Peninsula
BShwSemi-arid steppeRain-shadow interior, parts of Rajasthan, Gujarat and Haryana
BWhwHot desertWestern Rajasthan
CwgWarm temperate with a dry winterGanga plain, eastern Rajasthan and large parts of the north-east
DfcCold, humid winter and a short summerArunachal Pradesh
EPolar or highlandHigh Himalaya, Ladakh

एवढे फरक असूनही मान्सून उपखंडाला एकच लय देतो — एकाच लग्नमांडवाखाली अनेक कुटुंबे असावीत तसे. जवळजवळ सगळीकडे शेतीचे वर्ष पावसाच्या येण्या-जाण्यावर; बहुतेक भागाला वर्षाचा पाऊस त्याच काही महिन्यांत. वाऱ्यांची एकच ऋतुबदल पूर्ण प्रदेश चालवते; चांगला किंवा वाईट मान्सून देशभर पिकांत, भावांत, धरणांत जाणवतो. हिमालय हिवाळ्यात मध्य आशियाची थंड हवा अडवून आणि उन्हाळ्यात मान्सूनला धरून ठेवून ही एकता शक्य करतो. पण आगमन, खंड, माघार दरवर्षी बदलत असल्याने अनिश्चितताही. (→ English: monsoon; unity of the monsoon · हिन्दी: मानसून; मानसून की एकता)

In exam EnglishFor all these differences, the monsoon gives the subcontinent a common rhythm. Almost everywhere the farming year turns on the arrival and departure of the rains, and most of India receives the bulk of its rain in the same few months of the year. The same seasonal reversal of winds controls the whole region, and a good or bad monsoon is felt across the country as a national event, in harvests, prices and the level of water in reservoirs. The Himalaya make this possible: the range keeps out the bitterly cold winter winds of Central Asia and, in summer, traps the rain-bearing monsoon air within the subcontinent. So the monsoon is seen as something that binds the country together, though it is also a source of risk, because its arrival, breaks and departure change from one year to the next.

या अनिश्चित व्यवस्थेचा अंदाज बांधते 1875 मध्ये स्थापन झालेली IMD — आता पृथ्वी विज्ञान मंत्रालयाखाली, मुख्यालय दिल्ली. प्रत्येक हंगामाचा पाऊस दीर्घकालीन सरासरीशी तुलना करते: अनेक दशकांतील देशभरातील जून–सप्टेंबरचा सरासरी पाऊस. 1971–2020 च्या आधारे तो सुमारे 87 सेंमी — विद्यार्थ्याचे गुण वर्गाच्या सरासरीशी तुलना करावेत तसे. तुलनेनुसार पाच गट: तुटीपासून अतिरिक्तपर्यंत. 'सामान्यपेक्षा कमी' असा अंदाज आला की सरकारे आधीच बियाणे, पर्यायी पिके, अन्नसाठा तयार ठेवतात. (→ English: long period average (LPA); India Meteorological Department · हिन्दी: दीर्घावधि औसत; भारत मौसम विज्ञान विभाग)

In exam EnglishForecasting this uncertain system is the task of the India Meteorological Department, set up in 1875 and now part of the Ministry of Earth Sciences, with its headquarters in New Delhi. IMD measures each season's rain against the long period average (LPA) (LPA): the average June-to-September rainfall over the whole country across a fixed run of years. IMD now calculates the LPA over 1971–2020, which gives a figure of about 87 cm. A season is then placed in one of five categories according to how its rain compares with the LPA, from deficient at the bottom to excess at the top, as shown in the table below. The categories matter beyond meteorology: a forecast of a below-normal season, for example, prompts governments to plan seed supplies, contingency crops and food stocks well before the rains arrive.
IMD's categories for south-west monsoon rainfall over India
CategoryRainfall as a share of the LPA
DeficientBelow 90%
Below normal90% to 95%
Normal96% to 104%
Above normal105% to 110%
ExcessAbove 110%

IMD नैऋत्य मान्सूनचा पहिला दीर्घकालीन अंदाज एप्रिलच्या मध्यात देते आणि मेच्या अखेरीस तो सुधारते — महिनानिहाय आणि प्रदेशनिहाय अंदाजांसह. 2021 पासून एकाच गणिती सूत्रावर न अवलंबता अनेक संगणकीय मॉडेल्सचे निकाल एकत्र पाहते — एकाच डॉक्टरऐवजी अनेक डॉक्टरांचे मत घ्यावे तसे. ही मॉडेल्स 2012 मध्ये पृथ्वी विज्ञान मंत्रालयाने सुरू केलेल्या राष्ट्रीय मान्सून मिशनअंतर्गत पुण्याच्या IITM मध्ये तयार झाली. एल निनो, हिंदी महासागर द्विध्रुव यांसारखे घटक विचारात घ्यावे लागतात; अंदाजाला त्रुटीची मर्यादा असते — 'सामान्य' म्हणजे वचन नव्हे, शक्यता. हंगामात काही आठवडे आधीचे अंदाज आणि उष्णता, मुसळधार पाऊस, चक्रीवादळांचे रोजचे इशारे. (→ English: long-range forecast; Monsoon Mission · हिन्दी: दीर्घावधि पूर्वानुमान; मानसून मिशन)

In exam EnglishIMD issues its first long-range forecast for the south-west monsoon in mid-April and updates it around the end of May, adding forecasts for individual months and for broad regions of the country. Since 2021 it has used a multi-model ensemble approach, which combines the output of several dynamical climate models instead of relying on a single statistical formula. The dynamical models came out of the National Monsoon Mission, which the Ministry of Earth Sciences started in 2012 and which built a coupled ocean–atmosphere forecasting model for India at the Indian Institute of Tropical Meteorology, Pune. Forecasts must weigh El Niño, the Indian Ocean Dipole and the other signals described in Part 1, and they carry a stated margin of error, so a 'normal' forecast is a probability rather than a promise. Within the season, IMD also issues forecasts a few weeks ahead and daily warnings for heat, heavy rain and cyclones.

तिन्ही भाग एकत्र पाहिले तर कारणाकडून परिणामाकडे प्रवास. भाग 1: यंत्रणा — दाब, वारे, ITCZ, जेट प्रवाह, तिबेट, एल निनो, IOD. भाग 2: चार ऋतू, स्थानिक वादळे, दोन शाखा, ईशान्य मान्सून, चक्रीवादळे. भाग 3: परिणाम — डोंगराजवळ मुसळधार, पर्जन्यछाया, पश्चिमेला कोरडी जमीन, पाऊस कमी तिथेच भरवसा कमी, दुष्काळ–पूर, हवामान प्रकार, अंदाज यंत्रणा. पेरणीपासून कापणीपर्यंत एकच दिनदर्शिका देणारा मान्सूनच शेती आणि पाणी धोक्यात ठेवतो — म्हणून भूगोल, अर्थव्यवस्था, आपत्ती व्यवस्थापन जिथे भेटतात असा विषय. (→ English: climate of India; monsoon · हिन्दी: भारत की जलवायु; मानसून)

In exam EnglishTaken together, the three parts of this chapter move from cause to effect. Part 1 explained the machinery: pressure and winds, the ITCZ, the jet streams, Tibet, El Niño and the Indian Ocean Dipole. Part 2 followed that machinery through four seasons, with their local storms, the two branches of the south-west monsoon, the north-east monsoon and cyclones. This part has shown the outcome: heavy rain where moist winds meet mountains, dry lands in the rain shadows and the far west, rainfall that is least reliable where it is scarcest, the twin risks of drought and flood, the climatic types that sum up the pattern, and the forecasting system that tries to see each season coming. The same monsoon that gives India a shared calendar also leaves its farms and water supply exposed, which is why the subject links geography with the economy and disaster management.

Exam traps

Recap

Practice questions

Q1. Which one of the following regions has the highest coefficient of variation of annual rainfall?

  1. Konkan coast
  2. Western Rajasthan
  3. Meghalaya plateau
  4. Lower Ganga plain
Show answer

Answer: B. Western Rajasthan

Variability rises as rainfall falls, and western Rajasthan, among the driest areas, shows a coefficient of more than 50 per cent. The Konkan coast, Meghalaya and the lower Ganga plain all receive heavy, dependable rain and so have a low coefficient of variation.

Q2. If the all-India rainfall of a south-west monsoon season is 93 per cent of the long period average, IMD would classify the season as:

  1. Deficient
  2. Below normal
  3. Normal
  4. Drought
Show answer

Answer: B. Below normal

90–95 per cent of the LPA is 'below normal'. 'Deficient' begins below 90 per cent; 'normal' is 96–104 per cent; 'drought' is not one of IMD's five all-India seasonal categories.

Q3. Consider the following statements about IMD's long period average (LPA) for the south-west monsoon:
1. It is now based on the period 1971–2020 and is about 87 cm.
2. It is the average rainfall of the whole calendar year, January to December.
Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2
Show answer

Answer: A. 1 only

Statement 1 is correct. Statement 2 is wrong: the LPA used for the monsoon forecast is the June–September average for the whole country. So '2 only' and 'both' are wrong, and 'neither' is wrong because statement 1 is true.

Q4. Match List I with List II:
List I (Köppen type) — List II (Region)
A. Amw — 1. Arunachal Pradesh
B. As — 2. Western Rajasthan
C. BWhw — 3. Coromandel coast
D. Dfc — 4. West coast south of Goa
Select the correct answer using the code given below:

  1. A-4, B-3, C-2, D-1
  2. A-3, B-4, C-2, D-1
  3. A-4, B-3, C-1, D-2
  4. A-2, B-3, C-4, D-1
Show answer

Answer: A. A-4, B-3, C-2, D-1

The pairs are A-4 (Amw, the coast south of Goa), B-3 (As, the Coromandel coast), C-2 (BWhw, the desert of western Rajasthan) and D-1 (Dfc, the cold, humid hills of Arunachal in the north-east). Option (b) swaps the two coasts; (c) swaps the desert and Arunachal; (d) puts the monsoon type in the desert.

Q5. Which of the following areas receive less than 50 cm of rainfall in a normal year?
1. Western Rajasthan
2. Ladakh
3. Konkan coast
Select the correct answer using the code given below:

  1. 1 and 2 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3
Show answer

Answer: A. 1 and 2 only

Western Rajasthan and Ladakh (a cold desert) receive under 50 cm. The Konkan coast, on the windward side of the Western Ghats, receives well over 200 cm, so every option that includes it is wrong.

Q6. Consider the following statements about IMD's definition of a heat wave:
1. On the plains, a heat wave can be declared when the maximum temperature is at least 40°C and 4.5°C or more above normal.
2. The same 40°C threshold applies to hill stations.
Which of the statements given above is/are correct?

  1. 1 only
  2. 2 only
  3. Both 1 and 2
  4. Neither 1 nor 2
Show answer

Answer: A. 1 only

Statement 1 is correct. Statement 2 is wrong: for hill stations the threshold is 30°C, because they are normally much cooler. So '2 only' and 'both' are wrong, and 'neither' is wrong because statement 1 is true.

Q7. A 'cloudburst', as described by the India Meteorological Department, refers to:

  1. About 100 mm or more of rain in an hour over a small area
  2. Rainfall more than 25 per cent above normal over a whole state in a season
  3. A thunderstorm with hail arriving from the north-west in the hot season
  4. A sudden rise of sea level along the coast during a cyclone
Show answer

Answer: A. About 100 mm or more of rain in an hour over a small area

A cloudburst is an extreme, very local downpour of about 100 mm or more in an hour. Option (b) describes a seasonal excess, not a short burst; (c) describes kalbaisakhi; (d) describes a storm surge.

Q8. Consider the following statements:
1. The India Meteorological Department was established in 1875.
2. The National Monsoon Mission was launched by the Ministry of Earth Sciences.
3. IMD issues its first long-range forecast for the south-west monsoon in mid-April.
Which of the statements given above are correct?

  1. 1 and 2 only
  2. 2 and 3 only
  3. 1 and 3 only
  4. 1, 2 and 3
Show answer

Answer: D. 1, 2 and 3

All three are correct: IMD dates from 1875, the Monsoon Mission (2012) is a Ministry of Earth Sciences programme, and the first long-range forecast comes in mid-April with an update around the end of May. Each of the other options leaves out a correct statement.

← Part 2All partsQuick recap →

Study this in the Upscore app to keep notes, save it for revision, track your practice scores and follow a plan to the exam date. It's free.

Study this in the app →

Sources