A thick blanket of fog engulfed Delhi on Tuesday morning, while the mercury dipped to 7 degrees Celsius, nearly a notch below the season's normal.

Low visibility due to the dense fog was reported from several areas of the city, such as Safdarjung, Anand Vihar and India Gate.

The visibility recorded at Delhi's main weather station at Safdarjung was 200 metres at 5:30 am. It was 100 metres at Palam.

About 30 flights, including international flights, were delayed at the Delhi airport due to the fog and low visibility, according to the airport authorities.

The arrival of 14 trains was also delayed due to the foggy conditions.

According to a weather forecast, very dense fog is likely to be witnessed in isolated pockets of Delhi and surrounding areas.

A thick layer of fog engulfed the city on Monday as well as the minimum temperature settled at 7.8 degrees Celsius.

Meanwhile, with a reading of 374, the Air Quality Index (AQI) of the national capital remained in the "very poor" category at 9:05 am.

An AQI between zero and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", and 401 and 500 "severe".

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