Air services may continue to be variously hit in the northwest of the country during the rest of the week too due to inclement weather.
At least two blasts of foggy and alternating cold weather are being forecast to materialise as causative western disturbances troop in by Thursday and Saturday.
Overnight on Monday, dense fog cut down visibility to below 200 m over Rajasthan, Haryana, Delhi, Uttar Pradesh and Madhya Pradesh, a Met Department update said.
Very dense fog (visibility below 50 m) has been reported from a few places both in the northwest and towards the East of the country.
MOISTURE CARRY Western disturbances are low-pressure systems over latitudes farther and away from the Equator.
They make up bothersome weather-generating systems during winter. They originate from as far away to northwest of India as in the Mediterranean or Caspian Sea and travel across Iran, Iraq, southwest Arabia, Afghanistan and Pakistan.
They carry moisture generated from the difference in temperature regimes across latitudes from Equator (low) to higher latitudes to North.
The moisture gets dumped as rain or snow in the hills (Himalayas) and thundershower or fog in the plains of northwest India.
The latest disturbance is expected to cross the border and enter northwest India by Tuesday, a Met Department update said on Monday.
WEATHER WARNING A weather warning valid for Tuesday said that very dense fog (visibility below 50 m) would hang over Punjab, Haryana, Delhi, west Madhya Pradesh, Uttar Pradesh and Rajasthan.
It will be dense (visibility below 200 m) over east Madhya Pradesh, Bihar and sub-Himalayan West Bengal.
Accompanying clouds will block the Sun and trigger ‘cold day’ conditions over Punjab; Haryana; Uttar Pradesh; Bihar; and Rajasthan. Ground frost has been warned of at isolated places over Punjab, Haryana and west Rajasthan.
On Wednesday, very dense fog may blanket Punjab, Haryana, Delhi, west Madhya Pradesh, Uttar Pradesh, and Rajasthan.
Dense fog is likely at east Madhya Pradesh; Bihar; and sub-Himalayan West Bengal.
Meanwhile in the South, a depression crossing the Sri Lanka coast will bring to moderate to heavy rainfall over south Tamil Nadu and parts of Kerala over the next two days.