KOCHI: Morning joggers in the city were in for a surprise as a thick layer of fog hung low in the atmosphere on Wednesday. The fog, which reduced visibility significantly, was unusually dry and many people complained of a foul smell in the air. While the air quality index was moderate, experts felt it could be smog which develops when pollutants in the air take time to dissolve.
“It could be atmospheric inversion, a horizontal layer that forms as surface temperature drops suddenly while the upper strata of the atmosphere stays hot. The inversion takes time to dissolve when the concentration of pollutants in the atmosphere is high,” said K Satheesan, associate professor in the Atmospheric Sciences Department, Cochin University of Science and Technology.
Recently, the city has been witnessing a significant change in climate with the days remaining hot and while it rains heavily at night. G Bindu, a scientist with the Nansen Environmental Research Centre, India (NERCI), also said the phenomenon was called radiation inversion, caused by the difference in temperature.
“While the earth’s surface cools down suddenly, the upper layer takes time to cool off. This creates a layer of cool air in the atmosphere. Water inversion or sea breeze can lead to such a formation. The presence of pollutants in the air and low level of moisture can cause smog. The pollutants will continue to become more concentrated until a change in weather disperses the inversion layer,” Bindu said.
Scientists at the Pollution Control Board regional centre said they were verifying the parameters to find out whether the concentration of particulate matter was high in the atmosphere. The experts said it was a normal phenomenon.