Air pollution lowering day temperatures during rains

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MUMBAI:A high level of air pollutants in parts of India has unexpectedly helped to lower daytime temperatures by 1 degree Celsius during the monsoon months. While this makes the day more pleasant, the long-term consequences may not be so good, scientists said. In a paper published in the British science journal Nature on September 14, professors and scientists from the Indian Institutes of Technology and University of Hyderabad have shown how pollutants – and not other meteorological factors – are responsible for lowering the temperature.

The study focused on what is called the Indian Summer Monsoon region over central and northern India, which has some of the cities with the worst air pollution levels in the world. Kanpur in Uttar Pradesh is infamous for being the most polluted city and others including Varanasi and Patna are not far behind. It is said that smaller cities like Korba, which do not have adequate measurement equipment, could be even more polluted. “The effects are manifold. We have bouts of heavy rainfall, instead of a few moderate spells,” said Sachchida Nand Tripathi, head of civil engineering at IIT Kanpur and one of the authors of the paper. That is what causes flash floods. Also, the monsoon flow itself gets affected.”

High levels of suspended pollutants – known as aerosols – in the air in India lead to the formation of giant, anvil-shaped rain clouds, which appear as towering columns with a vast, flat top surface.

Source: Economic Times