Dense fog has enveloped Delhi and parts of North India, leading to a red alert from the India Meteorological Department (IMD) and severe disruptions. Visibility dropped to as low as 50 meters, causing the cancellation of 128 flights and delays for nearly 200 others at Delhi's Indira Gandhi International Airport. Air quality also worsened, returning to the 'severe' category with AQI levels exceeding 400. Road and rail traffic have also been impacted, with authorities urging caution for travelers and residents.