A thick blanket of fog enveloped the national capital, causing disruptions in traffic movement as the city awoke to an exceptionally cold Sunday. During the early hours of the day, the RK Puram Area recorded a minimum temperature of 7 degrees Celsius. As many as 22 trains to Delhi from various parts of the country are running late due to dense fog conditions. Several flights have also been delayed. The city experienced its first cold wave day on Friday.