Air pollution: Bad air responsible for inconstant rainfall, says study

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The rising air pollution across cities have caused irregular and changeable behaviour of monsoon rainfall in India, said a study. The study, published in the reputable journal, Nature Communications on Friday, conducted by a team of scientists from IIT (Indian Institute of Technology), Kanpur has explained in detail about how the excess aerosols, suspended solid particles i.e smoke, dust and industrial waste, in the atmosphere is making a difference in shape, size of cloud patterns, variations in temperature etc. SN Tripathi, a professor at the Centre for Environmental Science and Engineering at IIT Kanpur and one of the members of the study said that aerosols are very important for the formation of cloud. Speaking to The Indian Express, Tripathi said, In the absence of aerosols, no clouds would be formed and consequently no rainfall will take place. But as we know, an excess of everything is bad. That is what is happening here. An increase in the aerosol content in the atmosphere, a direct consequence of rising air pollution, is interfering with the stable cloud formation system and influencing rainfall patterns. He added that the changes in structure and dynamics of a cloud are leading to sharp variability in monsoon. This year, Nagpur and Ujjain witnessed unusually heavy rainfall on certain days. Such rainfall events are not normal. We suspect that changing cloud dynamics could have a role to play in events like these. The high pollution levels are not just changing cloud shape and size and depth, but also its microstructure, Tripathi told the daily. The other members of the team which conducted the study are – Chandan Sarangi (student of Tripathi), Vijay Kanawade (University of Hyderabad), Abin Thomas (University of Hyderabad) and Dilip Ganguly (IIT Kanpur). Using data from satellite and atmospheric computer models from the last 16 years, the team evaluated the impacts of changes in the behaviour of cloud over a land area of around 16 lakh square kilometres. The connection between air pollution and a decline in rainfall were found in earlier studies too. However, for the first time, this team has given the exact data of the changes that occurred due to aerosols in the clouds in India, which also lead to a reduction in the difference in day and night temperatures. Since the tragedy in 2013 in Uttarakhand, India is witnessing an unusually extreme rainfall event each year.