Delhi-NCR’s Record-Breaking Fog: What Caused The Blinding Haze?

The national capital region (NCR), including Delhi, Ghaziabad, Noida, and Gurugram, recently witnessed an unusual and extreme spell of fog, one that surpassed typical winter fog conditions. This dense, ghostly fog blanketed the region starting Friday night, persisting well into Saturday morning. According to the India Meteorological Department (IMD), this was the longest fog spell of the season, leading to severe disruptions across the city. Flights, trains, and road traffic faced significant delays as zero visibility conditions took hold.

The Science Behind the Fog

Fog, which often forms during the winter months in Delhi-NCR, occurs when cool air near the ground condenses moisture into tiny water droplets, reducing visibility. Typically, this phenomenon happens at night when temperatures drop, causing the air to cool quickly. Factors such as low wind speeds, high humidity, and specific topographical conditions in the Indo-Gangetic Plains exacerbate fog formation. This region, which includes Delhi, is particularly vulnerable to persistent fog due to its flat, low-lying terrain that restricts airflow and traps fog for extended periods.

Meteorological Factors Behind the Recent Fog

Several meteorological factors combined to create the record-breaking fog in Delhi-NCR. One major cause was a significant drop in temperature, which is typical during winter in the region, especially in the early morning. As temperatures fall, the moisture in the air condenses, leading to fog. Additionally, low wind speeds contributed to the fog’s persistence, as winds usually help disperse fog, but in this case, light breezes allowed the fog to linger for hours.

Another important factor was the presence of a western disturbance in the region, which interacted with easterly winds, bringing rainfall and thunderstorms to parts of northwest and central India. While the rain helped increase the moisture levels in the air, it also provided the necessary conditions for dense fog. The high humidity levels caused by moisture from the Arabian Sea and Bay of Bengal intensified the fog formation.

Air Pollution’s Role in the Foggy Situation

Delhi-NCR’s air quality, which was already poor due to ongoing pollution, made the fog situation worse. The combination of calm winds, high humidity, and pollutants such as vehicle emissions and construction dust trapped the pollutants near the surface, making the fog even denser. On Sunday, the city’s Air Quality Index (AQI) registered a “very poor” level of 372, significantly impacting the health of residents.

The fog caused severe disruptions across the region, with zero visibility recorded at Palam between 4 am and 7:30 am on Sunday. On the previous day, Saturday, a nine-hour spell of zero visibility made travel across Delhi-NCR nearly impossible. The hazy conditions persisted for a third consecutive morning, leading to further disruptions in road, train, and air traffic.

While fog is a common occurrence in Delhi-NCR during the winter, this extreme fog event, exacerbated by a combination of meteorological factors, high humidity, and pollution, was unprecedented. The blinding fog, coupled with the region’s poor air quality, caused significant disruptions to everyday life, making it a significant weather event for the national capital. Residents of Delhi-NCR are advised to stay vigilant as weather conditions continue to fluctuate in the coming days.

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