After two days of dense to very dense fog, visibility improved in many parts of Delhi on Friday as most fog transformed into low clouds, according to the India Meteorological Department (IMD).

Dense to moderate fog conditions were witnessed in isolated pockets of the capital in the early hours of the day.

The IMD said the improvement in visibility can be attributed to the breaking of the inversion layer this morning, in contrast to the conditions observed from December 25 to 28, indicating weakening of the lower-level stable boundary layer.

The visibility was 200 metres at Safdarjung, Delhi's main weather station, and 50 metres at Palam.

Train services were impacted due to fog for the third day with 11 Delhi-bound trains delayed.

"Fog conditions at IGIA improved significantly on Friday, with the lowest visibility at 150 metres in dense fog," the IMD said.

Runway Visual Ranges (RVRs) now range from 400 to 800 metres, indicating improved aviation conditions, it said.

The minimum temperature in Delhi was recorded at 10.7 degrees Celsius, four notches above the season's average, the weather department said.

The relative humidity stood at 95 per cent at 8:30 am.

Delhi Air Quality Index (AQI) was recorded at 332, in the 'very poor' category, at 8 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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