India, Feb. 2 -- Aided by calm winds, a dense blanket of fog engulfed Delhi-NCR on Saturday morning, with parts of the national Capital recording zero visibility. The India Meteorological Department (IMD) has issued a yellow alert for Sunday, warning people of moderate to dense fog in the early hours of the day.

Visibility at Palam dropped to 150m by 1.30am on Saturday, with the wind speed varying between 2-3 kmph. Later, the visibility dropped to 50m by 5.30 am and remained the same till 8am. It improved to 100m by 9am, when the wind speed was 4kmph, according to IMD.

Safdarjung, representative of Delhi's weather, recorded moderate fog at 1.30am, with visibility dropping to 200m at the same time, which further dropped to 50m at 7am and...