For the past few days, fog and mist have been present in the Terai districts from east to west. This foggy weather has caused temperatures to drop continuously, making it feel much colder.
However, meteorologists say that a cold wave, like in previous years, has not yet started in the Terai districts of Madhesh.
According to the Meteorological Forecast Division, there is currently no significant weather system in Nepal. Therefore, there is no immediate chance of rain or snowfall. However, today there is a possibility of partial clouds in Gandaki and Lumbini provinces.
Because the atmosphere is stable, the fog and mist in the Terai regions are likely to stay for a few more days. Later, the influence of western winds may reduce the fog and mist to some extent, meteorologists said.
What are Fog and Mist? Why Do They Occur?
At night, after the ground cools down, the temperature drops in the air, and many water droplets appear. This is fog and mist. When fog and mist form, visibility decreases, making it hard to see distant objects.
According to the Meteorological Forecast Division’s website:
- Fog: Visibility less than one kilometer.
- Mist: Visibility between one to five kilometers.
In the Terai regions from east to west, there are areas with fog and others with mist. Satellite images show that fog and mist cover the Terai regions of Nepal, extending from neighboring Indian states like Uttar Pradesh and Bihar. Therefore, in the early morning when visibility is low, vehicles need to drive with their headlights on.
Generally, the higher you go in the atmosphere, the colder it gets. During fog and mist, temperatures drop slightly above the ground and then rise again. Meteorologists call this condition “inversion.” Currently, there is an inversion. On the other hand, when the atmosphere is stable and lacks moisture, fog and mist form.
“As long as the atmosphere remains stable, these conditions will not change, and fog and mist will continue,” said senior meteorologist Shanti Kandel. “That’s why thick fog and mist have been present for the past one or two days, and the maximum temperatures have dropped, making it feel cold.”
In the Terai districts, fog and mist are present throughout the day. In the morning, there is fog, which turns into mist during the day, making the sky appear cloudy and slightly improving visibility.
Fog and Mist May Decrease in One or Two Days
“There is a possibility that fog and mist will decrease in one or two days,” Kandel added.
“If a weather system arrives and makes the stable atmosphere unstable, the fog and mist will clear,” she said. “This would require rain or winds. Currently, there is no chance of rain or wind. However, a low-pressure system might appear slightly to the west, causing partial clouds and reducing fog and mist.”
Starting Friday, Push 19, there is a possibility of a light low-pressure area forming in eastern Nepal. This will make the atmosphere unstable and reduce fog and mist like yesterday and today.
Why Do Fog and Mist Make It Feel Cold?
When fog and mist occur, the maximum temperature drops more than the minimum temperature, making it feel colder. Instead of just feeling cold in the early morning and evening, people feel cold throughout the day because there is no sunshine. Fog and mist change the usual temperature pattern, causing a persistent chill.
“The difference between maximum and minimum temperatures is not very large,” Kandel says. “It is cold in the morning, sunny in the afternoon, temperatures rise, and then cold again at night. Fog and mist change this pattern, making people feel a constant cold, like a biting chill.”
In the districts with fog and mist, maximum temperatures have been dropping continuously, making it feel cold. In the Kathmandu Valley, the minimum temperature this morning was measured at 5.2 degrees Celsius.