India, Dec. 20 -- Large parts of north India woke up to dense fog on Saturday as cold weather tightened its grip, sharply reducing visibility across several states including Delhi, Punjab and Uttar Pradesh. The weather conditions disrupted road and air travel in many areas, prompting advisories from aviation authorities and airlines.

The India Meteorological Department (IMD) said dense fog was reported "at most places over Punjab, at a few places over West Uttar Pradesh, at isolated places over East Uttar Pradesh and Haryana Chandigarh & Delhi".

In the national capital, dense smog persisted through the morning hours in areas such as Rao Tula Ram Marg, Akshardham, Sarai Kale Khan and Bhairav Marg.

In a detailed forecast, the weather off...