The northwest region of India has been experiencing unusual cold wave conditions for several days, with dense fog causing disruptions to air, rail, and road traffic, as well as leading to a number of road accidents.

The India Meteorological Department (IMD) notified on Wednesday that the minimum temperature in some parts of NorthWest India is expected to increase by around 2 degrees on January 12, 2022. The temperatures are, however, expected to fall again by 3-5°C from January 14-16 for northwest and central India, as reported by news agency ANI.

Why is it so cold in north India?

A cold wave is a weather phenomenon characterised by a prolonged period of excessively low temperatures that can be dangerous to human health. The severity of a cold wave is determined by the minimum temperature: it is considered a cold wave when the minimum temperature falls below 4 degrees Celsius in low-lying areas, or when the minimum temperature is at least 4.5 to 6.4 degrees Celsius below normal.

A severe cold wave is declared when the minimum temperature drops below 2 degrees Celsius.

Also read: 26 trains, 45 flights delayed in Delhi amid biting cold — Check cold wave alerts in other states here

RK Jenamani, IMD scientist, told Indian Express in an interview, said that large-scale fog cover is one of the main reasons contributing to the cold wave conditions in the region.

“While westerly and northwesterly winds of around 5 to 10 kmph in the afternoon have also been contributing to the dip in temperature, an important factor this month is fog, which has been lasting for longer durations, preventing sunlight from reaching the surface and affecting the radiation balance,” he said.

It can, to some extent, be explained by the western disturbances. The city's landlocked nature and proximity to the Himalayas also contribute to its cold temperatures.

Also read: Check out how foggy/cold Delhi will be this week before booking your flights or trains

"The long cold wave spell in Delhi can be attributed to a large gap between two western disturbances which allowed the chilly northwesterly winds from the mountains to affect the plains for a longer-than-usual period," Mahesh Palawat, Vice President for Meteorology and Climate Change of Skymet Weather, told PTI.

What will be the weather for a few days?

According to the India Meteorological Department (IMD), the capital is expected to have cloudy weather and light rain for the next two days due to a strong western disturbance affecting northwest India. Additionally, a dense cover of fog in the morning resulted in visibility of only 50 metres in Delhi, causing disruptions to transportation including vehicles and trains.

"A layer of dense to very dense fog extended from Punjab to Bihar across Haryana, Delhi and Uttar Pradesh in the morning," an IMD official said as reported by PTI.

Also read: Explained | Why is Delhi colder than Mussoorie and Shimla?

(Edited by : Sangam Singh)