Dense Fog and Smog Paralyse Delhi NCR Transport: Reasons Explained
Key Takeaways
- Dense fog reduced visibility to as low as 50 metres across parts of Delhi NCR.
- Air, rail and road transport faced major disruptions due to poor visibility.
- Weak winds, high humidity and temperature inversion intensified fog and smog.
- Weather conditions are likely to improve from December 16 as winds strengthen.
Severe Fog Disrupts Daily Life
Residents of Delhi NCR woke up to a thick blanket of dense fog and smog on December 15, severely affecting daily life and transportation. Visibility levels dropped sharply, reaching as low as 50 metres at the Indira Gandhi International (IGI) Airport between 07:00 and 09:00 hours. Runway visibility also reduced to around 75 metres, resulting in multiple flight cancellations and widespread delays. According to reports, more than 150 flights were delayed during the morning hours.
Rail and Road Transport Hit
Rail services were also impacted, with several trains running behind schedule due to poor visibility. Road and highway conditions worsened as visibility dipped to near-zero levels in many areas, increasing risks for commuters and slowing traffic movement across the region.
Meteorological Factors Behind Dense Fog
The primary reason for the development of such dense fog has been a change in wind direction from northwesterly to easterly and southeasterly. Since the evening of December 13, wind speeds have weakened significantly. The inflow of moist easterly winds increased humidity levels, while temperatures remained low. Low wind speed, high humidity and low temperatures together created ideal conditions for fog formation.
Role of Temperature Inversion and Smog
Another important contributing factor has been temperature inversion. Under normal conditions, temperature decreases with height, but during an inversion, temperature increases with altitude, preventing vertical mixing of air. As a result, cold and heavy air, along with pollutants, remained trapped near the surface. This trapping effect worsened air quality and enhanced fog persistence.
With cold temperatures and high humidity, fog intensified further, allowing pollutants such as dust, smoke particles and harmful gases to adhere to tiny water droplets. This combination led to smog formation, deteriorating visibility and air quality across the region.
Weather Improvement Likely Ahead
Weather conditions are expected to improve gradually from December 16 onwards. Wind direction is likely to shift back to northwesterly, bringing in drier and colder winds with higher speeds. This change is expected to help disperse pollutants, reduce moisture levels, and lead to a gradual improvement in visibility and a decline in fog intensity over Delhi NCR.
Residents of Delhi NCR woke up to a thick blanket of dense fog and smog on December 15, severely affecting daily life and transportation. Visibility levels dropped sharply, reaching as low as 50 metres at the Indira Gandhi International (IGI) Airport between 07:00 and 09:00 hours. Runway visibility also reduced to around 75 metres, resulting in multiple flight cancellations and widespread delays. According to reports, more than 150 flights were delayed during the morning hours.
Rail and Road Transport Hit
Rail services were also impacted, with several trains running behind schedule due to poor visibility. Road and highway conditions worsened as visibility dipped to near-zero levels in many areas, increasing risks for commuters and slowing traffic movement across the region.
Meteorological Factors Behind Dense Fog
The primary reason for the development of such dense fog has been a change in wind direction from northwesterly to easterly and southeasterly. Since the evening of December 13, wind speeds have weakened significantly. The inflow of moist easterly winds increased humidity levels, while temperatures remained low. Low wind speed, high humidity and low temperatures together created ideal conditions for fog formation.
Role of Temperature Inversion and Smog
Another important contributing factor has been temperature inversion. Under normal conditions, temperature decreases with height, but during an inversion, temperature increases with altitude, preventing vertical mixing of air. As a result, cold and heavy air, along with pollutants, remained trapped near the surface. This trapping effect worsened air quality and enhanced fog persistence.
With cold temperatures and high humidity, fog intensified further, allowing pollutants such as dust, smoke particles and harmful gases to adhere to tiny water droplets. This combination led to smog formation, deteriorating visibility and air quality across the region.
Weather Improvement Likely Ahead
Weather conditions are expected to improve gradually from December 16 onwards. Wind direction is likely to shift back to northwesterly, bringing in drier and colder winds with higher speeds. This change is expected to help disperse pollutants, reduce moisture levels, and lead to a gradual improvement in visibility and a decline in fog intensity over Delhi NCR. Trending: 2025 Set to Be Second or Third Warmest Year on Record: WMO, But Why?
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