The Delhi-NCR region is currently engulfed in haze. Smog is a mixture of fog and smoke that is primarily generated by pollution. In a few days, when the temperature continues to fall, fog, rather than smog, will dominate the cityscape.
Seeing fog throughout the winter is a very typical occurrence. Have you ever thought about how and why it forms? This question was posted on the internet community Quora.
What causes fog during the winter?
To begin with, fog is fairly common in winter, particularly in northern India. Cooler temperatures increase the likelihood of fog formation.
Fog reduces vision to less than one kilometer. During the cooler months, water evapourates and becomes invisible as water vapour from morning dew, lakes, and rivers.
They accumulate dust, smoke, and soot particles, causing water droplets to become visible and resulting in fog. The air swiftly cools at night, forcing the vapour to condense back into water droplets.
Why do we get to see fog?
The concept was presented in a Quora answer written by a paraglider pilot who is also a meteorology teacher. He defined fog as “clouds that form at zero altitude above ground level.” This is more likely to occur during high-pressure systems in the winter because wind speeds are so low that the fog cannot clear itself.
Another user responded that on a clear winter night, the ground cools significantly, which cools the air in direct contact with it, causing it to reach the dew point—the temperature at which water vapour in the air condenses into small droplets.
Above the surface cloud layer (fog), the air is slightly warmer. This is known as an inversion.
Another user provided a simple explanation, stating that as the nights lengthen in winter, we frequently see clear and cloudless skies at night. As the air cools at night, the relative humidity rises, which can lead to fog development.
How is fog different from mist?
Mist is not the same as fog. While both appear similar, mist contains minute droplets of water on suspended particles of air, causing sight issues. Mist is thinner and lighter than fog, which is much thicker and denser. Mist also has a limited lifespan.
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