Cold wave grips Delhi, mercury dips to 3.2 degree Celsius
What's the story
A cold wave gripped Delhi on Wednesday as frosty winds from the snow-clad western Himalayas continued to sweep the plains and brought the minimum temperature down to 3.2 degree Celsius, the Indian Meteorological Department (IMD) informed. Dense fog blanketed parts of the city, lowering visibility to 50 meters and affecting traffic movement.
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Minimum temperature is four notches below normal
"Cold wave conditions prevailed at the Safdarjung Observatory, which provides representative data for the city. It recorded a minimum of 3.2 degree Celsius, four notches below the normal," said Kuldeep Srivastava, the regional forecasting center head of the India Meteorological Department (IMD).
IMD
When is a cold wave and severe cold wave declared?
In the plains, the IMD declares a cold wave if the minimum temperature dips to four degree Celsius. A severe cold wave is when the minimum temperature is two degree Celsius or less. "Cold and dry northerly/northwesterly winds from the western Himalayas have been barrelling through the plains, bringing down the minimum temperature in north India," Srivastava said.
Dense fog
Dense fog lowered visibility at Palam and Safdarjung
"Similar conditions will prevail in the city over the next two days," Srivastava said. "Dense fog lowered visibility to 50 meters at Palam and 200 meters at Safdarjung," the IMD said. Delhi had been registering above-normal minimum temperatures till Monday, as a cloud cover persisted over the city under the influence of successive Western Disturbances (WDs).
Information
What is a very dense fog?
According to the IMD, very dense fog is when the visibility is between 0 and 50 meters. In the case of "dense" fog, the visibility is between 51 and 200 meters, "moderate" 201 and 500 meters, and "shallow" 501 and 1,000 meters.
Temperature
Temperature dropping because of cold northwesterly winds
The temperature started dropping with the commencement of cold northwesterly winds after the withdrawal of the latest WD. Delhi's minimum temperature had settled at 4.8 degree Celsius on Tuesday, 7 degree Celsius on Monday, 7.8 degree Celsius on Sunday, 10.8 degree Celsius on Saturday, 9.6 degree Celsius on Friday, and 14.4 degree Celsius on Thursday, the highest in January in four years.