Brace yourself for another season of fog, which is expected to set in at the Delhi airport by the second week of December.
“All conditions and trends, like cold weather, are in place for a normal fog season this winter,” said R.K. Jenamani, director of the Meteorological Department, IGI Airport.
On an average, the IGI airport witnesses 87 hours of dense fog (visibility below 200 metre) spread over 11 days every year.
The exact figures can wildly vary from year to year.
Last winter was one of the worst for the IGI Airport with 167 hours of dense fog witnessed over 23 days.
The airport had to be completely shut down on three occasions.
The previous winter season (2008-2009) saw only 10 hours of dense fog.
Jenamani said though the airport witnessed a long fog season last winter, the number of flights that had to be diverted had come down by 43 per cent.
“Despite so many hours of dense fog, only 147 flights had to be diverted. Compare this to 2006-2007 when 104 flights were diverted while the airport only saw 66 hours of dense fog,” he said.
“Like last year, the Met department will provide weather conditions for passengers, airlines and the airport operator, so that there are least disruptions due to the fog,” he said.
Another reason was the availability of the new runway 29/11, which is CAT IIIB enabled, that allowed pilots to land in near zero visibility.
Fog forecasts on the met department’s website — www.imd.gov.in — would be refreshed every two hours instead of six.
Delhi getting worse
According to the data of last 28 years available with the met department, the IGI airport now witnesses more dense fog than it saw in the 1980s.
The airport witnessed between 20 to 40 hours of dense fog (visibility below 200 metre) every January between 1982 and 1997, but the figure has been roughly between 60 and 100 hours in the last decade.
“The main reason behind this is rise in pollution, decrease in temperature and increasing urbanisation around the airport,” Jenamani said.
The wind that blows away the fog is another factor.
“There has been a 50 per cent reduction in wind speed at the airport from 1981 to now,” he said.