Moderate to dense fog is anticipated to impact visibility during the 75th Republic Day celebrations in the capital on Friday, as reported by the India Meteorological Department (IMD) on Thursday.
The IMD said that visibility may be limited to 400 meters until 8:30 am due to foggy weather, gradually improving to 1,500 meters by 10:30 am.
The minimum temperature is expected to range from 5 to 7 degrees Celsius, according to the Met office.
The persistence of a thick layer of fog over the plains in the region since December 25 is attributed to the absence of active western disturbances (WD) weather systems originating in the Mediterranean region and causing unseasonal rainfall in northwest India, IMD said.
Typically, five to seven WDs impact the region during these months, but there has been a lack of strong WDs this winter.
The IMD points out that two WDs have affected the country so far one in December and another in January with their impact confined to Gujarat, north Maharashtra, east Rajasthan, and Madhya Pradesh.
The formation of fog requires weak low-level winds, moisture, and overnight cooling. Strong WDs, characterized by intense winds and precipitation, disrupt these conditions.
The prevailing El-Nino conditions, marked by abnormal warming of surface waters in the central Pacific Ocean, are also contributing to the lack of active WDs. (With inputs from PTI)