In the National Capital, heavy fog enveloped the IGI airport this morning, disrupting the schedule of over a dozen flights. According to an airport official, about 13 domestic and international flights were delayed by upto two to three hours after fog descended on the airport in the wee hours on Christmas morning.The general visibility dropped to less than 50 metres while the runway visibility dropped to 100 metres on the main runway while it hovered between 500 to 125 metres on the new runway.Meanwhile, the cold wave further intensified in Kashmir division today as the night temperature in Leh town of Ladakh region plummeted by nearly seven degrees to settle at a low of minus 16.4 degrees Celsius. A MeT department official said, Leh was the coldest place followed by Kargil town where mercury stayed 11.6 degrees below the freezing point. The night temperature dipped in most parts of the Kashmir Valley. Pahalgam health resort in south Kashmir was the coldest place witnessing a minimum temperature of minus 7.6 degrees .Famous ski resort of Gulmarg in north Kashmir was the second coldest place at minus 7 degrees. Cold conditions prevailed in Punjab, Haryana and Chandigarh as the minimum temperature was two degrees Celsius below normal in the region.Road traffic was disrupted at various places in the region due to the morning fog and mist. A weather office spokesman said, Amritsar with 2.5 degrees Celsius, was the coldest place in the region.