THE CHALLENGING MONSOON EDITOR in CHIEF: Nakul Parashar
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VIPNET NEWS—VIGYAN PRASAR NETWORK OF SCIENCE CLUBS MARCH 2021 VOL 1 NO 13 5 THE CHALLENGING MONSOON EDITOR IN CHIEF: Nakul Parashar EDITOR: Arvind C. Ranade EDITORIAL PRODUCTION: Arvind C. Ranade Bipro Kumar Sen EDITORIAL: Sumita Mukherjee ADDRESS FOR CORRESPONDENCE: Vigyan Prasar, A-50, Festival of Science and Institutional Area, Sector-62, Noida-201 309, U.P, India festival of colour Tel: +91-0120 2404430 he month of February is programme, wherein India launched one Fax No: +91-0120-2404437 remembered for the National Brazilian satellite and 18 co-passenger E-MAIL: Science Day that is celebrated satellites through PSLV-C51 rocket. What [email protected] on February 28. The Noble is important to note is that Indian Space Prize by Sir C. V. Raman is most inspiring Research Organization (ISRO) has also WEBSITE: on many counts. His ingenious research opened the scope for private players. Out http://www.vigyanprasar.gov.in as well as the indigenous spectroscope of 18 satellites, 14 are from New Space In- designed by him showed the world that dia Limited (NSIN) and 4 are from Indian with limited facility a nation can be National Space Promotion and Authoriza- ‘Self-Reliant’ in science and technology. tion Center (IN-SPACe). 28 February 1928 was the day on which Likewise, the month of March is also Sir C V Raman announced his work to going to be full of celebration in science. Vigyan Prasar is not the public and to commemorate that, the We will be celebrating 3 March as World responsible for the day is celebrated as National Science Day Wildlife Day, 8 March as International statements/opinions expressed since 1987. Women Day, 21 March as World Forest and photographs used by Many of our clubs also celebrated the Day, 22 March as World Water Day, 23 the authors in their day with great enthusiasm. They organ- March as World Meteorology Day and 24 articles/write-ups ized lectures, seminars, competitions and March as World Tuberculosis Day. We all published in “Curiosity” events based on interviews of eminent should make use of these days to commu- scientists. These activities and events nicate the message of science to the peo- Articles, excerpts from articles will be highlighted in our April issue of ple around us. This month, we have a spe- published in “Curiosity” may VIPNET Curiosity. cial article on the World Meteorology Day be freely reproduced with February 2021 was also special, where- emphasizing the importance of weather, due acknowledgement/ in two space missions attracted the atten- climate and water and its significance for credit, provided periodicals tion of the science enthusiasts. One was humans. The regular columns of VIPNET the successful landing of NASA’s Persever- Curiosity are continuously attracting the in which they are reproduced ance Rover on the planet Mars. Persever- imagination of our club members and are distributed free. ance started its journey on 30 July 2020 especially the children. In addition to the and reached Mars on 18 February 2021 celebration of science, we are also going Published and Printed by after its six-month-long space travel. The to celebrate the festival of colours on 29 Dr Nakul Parashar on behalf few released photographs promise very March 2021. We wish you a very happy, encouraging results and it is expected to secure and eco-friendly Holi! of Vigyan Prasar, be a successful mission with fulfilling its A-50, Institutional Area, objectives like finding habitability, tracing Sector-62, biosignatures, testing certain samples and Dr. Arvind C Ranade is Scientist ‘F’ and Noida-201 309, U.P, India finding useful information on the scope National Co-ordinator of Vigyan Prasar for human expedition to Mars. Febru- Network of Science Clubs. ary was also important for India’s space Email: [email protected] Cover Design & Illustrations By: Bipro Kumar Sen 2 March 2021 THE CHALLENGING MONSOON Ashwini Ranade very year we celebrate ‘World my is heavily dependent on monsoon delineate the difference in weather dur- Water day’ and ‘World Mete- rains. Even after many decades of devel- ing cool dry winter to hot wet summer. orological Day’ consecutively opment, monsoon has a great impact on The notion of periodic changes in the on 22nd and 23rd March, agriculture, food security, and economy wind directions used for monsoon is for celebrating weather, climate and of the country. Even though southwest not indigenous and was taught by Arab water. Since 1961 ‘World Meteorological monsoon (during June-September) is navigators. Each year during boreal Organization’ (WMO) chooses a special the major contributors (nearly 70-90%) (northern hemispheric, NH) summer, theme to focus the attention of the of annual rainfall over most parts of the the initial monsoon rains occur over the world on crucial global issues related to country, due to insufficient irrigation Andaman Sea in May and then advanc- weather and climate. ‘The Ocean, our facilities, about 64% of Indian farmers es in north and north-west direction climate and weather’ is the theme cho- still rely upon monsoon for agriculture across the Bay of Bengal and over the sen for World Meteorological Day-2021 and in turn their livelihood. Good mon- south and southeastern parts of the to support efforts to boost ocean health soon is important to restock 81 major Indian subcontinent. There is a season- for sustainable development of ocean reservoirs in the country necessary al reversal of wind direction over the and to make aware of linkages between for irrigation, power generation, and northern Arabian Sea during summer the ocean, climate and weather. The drinking. The start, end, and duration from winter. During July, north-west- theme for the World water day-2021 is of the rainy season over each part of the erlies over the Red Sea, the northern ‘Valuing water’ to pay attention to the country are vital and any deviation in Arabian Sea and along Indian West protection of this essential life resource. these factors in any region would have Coast make forward journey, and dur- Owing to our tropical monsoon a significant impact on the agricultural ing November, northeasterly over the climate, Indian hydro-meteorological production and economy of that region. northern Arabian Sea and southeasterly planning and management services are wind over the Red Sea make backward highly dependent on the performance of Understanding the Monsoon journey favouring the sailors. Subse- summer monsoon. In the colonial era, it ‘The Monsoon’ is one of the oldest quently, the term ‘seasonal reversal of was considered that the Indian econo- observed weather phenomena that the wind’ has been extended to a similar pattern of winds in other parts of the world delineating monsoonal regime and monsoonal rains across many con- tinents and oceans across the globe (e.g. Asia-pacific, African, Australian, and American Monsoon etc.). Asia-Pacific monsoon is the most energetic, distinct and largest monsoon system of the globe, covering Indian subcontinent, In- do-china peninsula, China, South China Sea, Korea, Japan and the Northwest Pacific Ocean. It is the amalgamation of six sub-regional interlinked monsoons (Indo-China Peninsula monsoon, South China Sea monsoon, South Asian mon- soon, East Tibet Plateau monsoon, East Asian monsoon and Northeast Asian March 2021 3 Fig. 1. Locations of different highs and lows in active Asia-Pacific Monsoon circulation system (1000 hPa, 500 hPa and 150 hPa represent 2 m, 5.5 km and 13.5 km height above ground, respectively) monsoon). Each sub-regional monsoon March as well September when both essential condition for the occurrence shows significant differences in its hemispheres are in a thermally bal- of summer monsoon circulation. Due to regional characteristics despite sharing anced condition. The modification and the availability of modern scientific data some common signals. Broadly, the redistribution of the general circulation analysis and visualization techniques, basic nature of the monsoon is tropical; take place during four months of the it is easier to elaborate in details on the however, characteristics of its secondary monsoon season. Monsoon circulation 3-D structure of monsoon circulation disturbances are wide-ranging, equato- is highly dependent on the tempera- (Fig. 1). Two surface heat low pressure rial through subpolar. The Indian mon- ture contrast between the equator and areas (the Middle East and China Mon- soon is the core component and other respective latitudinal belts and is driven golia) converge airs from all other sides. sub-regional and local monsoons are by the apparent movement of the Sun. The rising air diverges through upper within the ambit of Asia-Pacific mon- Thermal gradients establish pressure tropospheric anticyclonic circulation soon circulation. Although the world- gradients and thereafter generate over the Tibetan plateau to all subtrop- wide acceptable definition of monsoon atmospheric motions. The combined ical and polar highs across the globe. regime continues to be debatable, it effect of thermal contrast between two During fully mature phase (July-Au- has been well accepted that the strong- hemispheres, land and sea, the low- gust), the deflected Indo-Pacific trade est, energetic, distinct and dominating er and upper troposphere (surface to winds after crossing the equator pass sub-monsoon is encompassed within ~10-12 km) and between elevated Asian through a wide range of thermal, mois- the Indian sector. landmass (Tibetan plateau) to the entire ture and wind regimes (e.g. tropical, Monsoon is the largest thermally globe is the main cause for the occur- subtropical, temperate and subpolar) direct tropical circulation that produces rence of monsoon. During NH summer, before converging over the heat lows summer seasonal rainfall across the the tropospheric temperature over the over Asian landmasses. A variety Asia-Pacific region. The classical image Tibetan plateau is ~10° C higher than of secondary perturbations finally of the global large-scale wind circu- that over the entire globe which acts produce the rainfall.