Dense fog enveloped Delhi for a second consecutive morning, leading to disruptions in air and rail traffic. Visibility dropped to zero in several areas, causing delays for 81 trains and diversions for 15 flights. The Met office attributed the fog to calm surface winds, and predicted continued dense to very dense fog throughout the day. Meanwhile, the national capital's air quality remained in the 'very poor' category, with an AQI reading of 380 at 9 am.