The India Meteorological Department (IMD) on Thursday issued a ‘moderate to dense’ fog warning during the 75th Republic Day celebrations in the national capital on Friday, adding that it may affect visibility. According to the weather department, the visibility is likely to be limited up to 100 to 400 meters till 8:30 am on Friday.

“The visibility is likely to improve after 8:30 am. It is likely to be around 500 to 800 meters with shallow fog from 10 am and further improve to 800 to 1,500 meters with mist or shallow fog from 10:30 am onwards,” the IMD said in its bulletin.

Notably, with ‘very dense’ fog visibility is between 0 and 50 meters, with ‘dense’ fog it is between 51 and 200 meters, 201 and 500 meters ‘moderate’, and 501 and 1,000 meters indicates ‘shallow’ fog.

Delhi-NCR and North India have been reeling under dense fog conditions for the last few weeks, leading to major delays or cancellations in trains and flights. Roadways are also being affected due to the low visibility, causing several accidents.

According to the IMD, the absence of active western disturbances that originate in the Mediterranean region and bring unseasonal rainfall to northwest India is one of the key reasons for the thick layer of fog that has persisted in the region since December 25.

“Generally, five to seven western disturbances impact the region during these months…Two WDs have affected the country so far – one in December and another in January – but their impact remained confined to Gujarat, north Maharashtra, east Rajasthan, and Madhya Pradesh,” an IMD official said, as quoted by news agency PTI.

Meanwhile, the IMD has predicted a minimum temperature of five to seven degrees Celsius in the national capital on Friday.

(With inputs from agencies)