A massive blanket of fog settled over the city this morning, severely disrupting air and rail traffic with 27 flights delayed and nearly 90 trains running late.Cold weather conditions continued to prevail in the national capital with the minimum temperature being recorded at 4.5 degrees Celsius, three notches below normal. The visibility according by MeT departments officials was 500 meters at 5.30am which decreased significantly to 50 meters at 8.30am.27 flights were delayed mainly in international arrival and domestic departure due to fog. According to a Northern Railway official, six trains have been cancelled. While 79 trains are running late due to the adverse weather conditions, departure timings of 10 others had to be rescheduled.Rajdhani trains originating from Dibrugarh, Bhubaneshwar, Sealdah and Ranchi were among the trains running late. The MeT has predicted that the sky will remain mainly clear during the day, with the maximum temperature hovering around 20 degrees Celsius. Yesterday, the maximum temperature was recorded at 21.2 degrees, while the minimum settled at 4.8 degrees Celsius.