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Why ‘hill station’ Delhi has been colder than Shimla, Mussoorie

NEW DELHI: Delhiites usually head to the mountains to beat the summer heat. But with Delhi-NCR in the grip of its second harshest December in 119 years, they could well have gone to the hills to get respite from the cold! Strange as it may seem, many parts of Delhi have been colder than popular hill stations such as Shimla and Mussoorie in the past few days, both during the day and night.

The maximum temperatures in both these hill towns over the weekend have been above 14 degrees Celsius. On both days, weather stations in the capital have registered lower temperature peaks. On Saturday, nearly all of Delhi had maximum temperatures below 14 degrees.

On Sunday, several weather stations — Jafarpur (11.6), Mungeshpur (11.9), Palam (13.5), among others — were under 14. Met officials say a major reason has been daytime fog cover over the plains, which has prevented sunlight from reaching the ground and heating it for most part of the day.

Night temperatures in Delhi were around 2 degrees lower than the two hill towns on Saturday. On Sunday too, several stations matched Shimla’s minimum of 2.8 degrees C while most others were colder than Mussoorie.

The northern plains have seen daily formation of morning fog over the past fortnight, which has been rising in height during the day to form an “uplifted fog”, or a very low cloud cover. This day time fog has been covering almost the entire northern plains, from the eastern regions of Pakistan to Bihar.

This cloud cover has been preventing sunlight from reaching the ground, making days overcast and chilly. The cover partially lifted for a longer period on Sunday, which allowed faint sunshine in Delhi-NCR, pushing up day temperatures by a notch or two as compared to Saturday.

“This fog/cloud cover has usually been only a few hundred metres above the ground. It’s too low to cover hill stations located at altitudes of 1,600-2,000m. In addition, there has been no rain in the hill states in the past few days. Which means, even if there’s morning fog in Shimla or Mussoorie, it’s lifting during the day to allow sunlight to heat the land,” said Kuldeep Srivastava, head of IMD’s regional weather forecasting centre here.

Indeed, day temperatures in both Shimla and Mussoorie have been three to four degrees above normal over the weekend, in the absence of wet weather.

The other factor that has been contributing to the record cold in the plains is icy northerly winds blowing relentlessly over the past fortnight, adding significantly to the chill in the region.

That is about to come to an end.

“The wind direction is likely to change on Monday when warmer easterly winds are expected in the region. This will certainly impact the weather and push up maximum temperatures by a couple of degrees,” Srivastava said. The change is wind direction is a precursor to a wet spell expected over northern India from December 31, the official said.

“We had earlier forecast light rain in Delhi-NCR on New year eve. Now, rain is more likely on January 1 and 2,” Srivastava said. This respite from severe cold is likely to be temporary as temperature are expected to drop again from January 3 or so.

Source: Economic Times