Why Delhi is so bitterly cold?

New Delhi, Himachal, J&K, Delhi, Punjab, Haryana, Bihar, UP and Rajasthan, cold has spared none.  

Why Delhi is so abnormally cold this season. Scientists too are unable to find the prime reason behind the chilly winds that have made days so night-like. This is certainly abnormal, say the scientists. The thick fog has cut down the solar radiation and heat reaching the earth. 

Weather scientists say Delhi had been experiencing the cold due to continuous fog and icy winds from the Himalayas. 

The national capital registered a record dip in the temperature as the mercury dipped to 1 degree Celsius. 

Meanwhile, cold wave is Punjab, Haryana, Uttar Pradesh and Bihar is expected to continue for the next few days.  

A media report quoted a weather scientist as saying, "Before 1997, we used to have more days with clear skies which kept the days warm". The reason for the continuous fog is higher levels of pollution, he added.

Besides the chill in the Capital, many parts of north India recorded sub-zero temperatures, say reports. 

According to a TOI report, January is usually considered the coldest month of Delhi winter, but the number of days with both the minimum and maximum temperatures remaining 'below normal' appears to be going up. In 1999, just two days in a row had seen both cold nights and cold days. The number of such days went up to three in 2003 and to four in 2010. In 2013, the number has already reached five.

A western disturbance that has prevailed in the northern parts of the country has brought cold winds and this explains the severe cold wave conditions.

A weather scientist was quoted by the media as saying moisture brought by a western disturbance in UP last week was trapped in the mid-tropospheric level preventing the Sun's radiation from reaching the earth. This aggravated the cold condition in the north.

Patna met director A K Sen was quoted in a TOI report as saying, "Extreme day cold condition has aggravated the chill. It all happened due to a western disturbance in west UP last week, which also reached Bihar borders. However, we did not receive rain as the condition shifted towards Nepal. But the moisture brought with the disturbance was trapped in the mid-tropospheric level (1.5 to 4km above the earth's surface), preventing the Sun's radiation from reaching the earth. We hope that the moisture will start clearing up in few weeks."