<p>Dense fog enveloped large parts of Delhi on Tuesday, lowering visibility to just 50 metres in some areas which affected road traffic movement, the India Meteorological Department (IMD) said here.</p>.<p>The weather office has predicted a cold day ahead.</p>.<p>A cold day is when the minimum temperature is less than or equal to 10 degrees Celsius and the maximum temperature is at least 4.5 degrees below normal. A severe cold day is when the maximum is 6.5 degrees or more below normal.</p>.<p><strong>Also Read: <a href="https://www.deccanherald.com/national/north-and-central/biting-cold-dense-fog-in-parts-of-punjab-haryana-1175181.html" target="_blank">Biting cold, dense fog in parts of Punjab, Haryana</a></strong></p>.<p>Delhi shivered under a "severe" cold day on Monday, when the maximum temperature dropped 10 notches below normal at some places.</p>.<p>The Safdarjung observatory, Delhi's primary weather station, recorded a maximum temperature of 15.6 degrees Celsius on Monday, six notches below normal and the lowest day temperature in December since December 18, 2020.</p>.<p>On Tuesday, Safdarjung logged a minimum temperature of 5.6 degrees Celsius -- a notch below normal. The maximum temperature is predicted to settle around 16 degrees Celsius.</p>.<p>Meteorologists attributed the sharp drop in day temperatures to frigid north-westerly winds barrelling through the plains and reduced sunshine due to foggy weather.</p>.<p>Mahesh Palawat, vice president (meteorology and climate change), Skymet Weather, said a western disturbance led to a fresh spell of snowfall in the mountains on December 25-26 and cold northwesterly winds are now sweeping through the plains after its retreat.</p>.<p>He said the wind chill factor -- a measure of the rate of heat loss from skin that is exposed to the air -- is also high.</p>.<p>The higher the wind speed during cold weather, the colder it feels on the skin if a person is outside.</p>.<p>Delhi clocked a top wind speed of 15 kilometers per hour (kmph) on Monday. Winds gusting up to 16 kmph are likely on Tuesday.</p>.<p>Dense to very dense fog prevailed in some parts of the National Capital Region (NCR), Haryana, Punjab, west Uttar Pradesh and north Rajasthan on Tuesday.</p>.<p>According to the IMD, "very dense" fog is when visibility is between 0 and 50 metres, 51 and 200 metres is "dense", 201 and 500 "moderate", and 501 and 1,000 "shallow".</p>.<p>In the plains, the IMD declares a cold wave if the minimum temperature dips to four degrees Celsius or when the minimum temperature is 10 degrees Celsius or below and is 4.5 notches below normal.</p>.<p>A "severe" cold wave is when the minimum temperature dips to two degrees Celsius or the departure from normal is more than 6.4 degrees Celsius.</p>
<p>Dense fog enveloped large parts of Delhi on Tuesday, lowering visibility to just 50 metres in some areas which affected road traffic movement, the India Meteorological Department (IMD) said here.</p>.<p>The weather office has predicted a cold day ahead.</p>.<p>A cold day is when the minimum temperature is less than or equal to 10 degrees Celsius and the maximum temperature is at least 4.5 degrees below normal. A severe cold day is when the maximum is 6.5 degrees or more below normal.</p>.<p><strong>Also Read: <a href="https://www.deccanherald.com/national/north-and-central/biting-cold-dense-fog-in-parts-of-punjab-haryana-1175181.html" target="_blank">Biting cold, dense fog in parts of Punjab, Haryana</a></strong></p>.<p>Delhi shivered under a "severe" cold day on Monday, when the maximum temperature dropped 10 notches below normal at some places.</p>.<p>The Safdarjung observatory, Delhi's primary weather station, recorded a maximum temperature of 15.6 degrees Celsius on Monday, six notches below normal and the lowest day temperature in December since December 18, 2020.</p>.<p>On Tuesday, Safdarjung logged a minimum temperature of 5.6 degrees Celsius -- a notch below normal. The maximum temperature is predicted to settle around 16 degrees Celsius.</p>.<p>Meteorologists attributed the sharp drop in day temperatures to frigid north-westerly winds barrelling through the plains and reduced sunshine due to foggy weather.</p>.<p>Mahesh Palawat, vice president (meteorology and climate change), Skymet Weather, said a western disturbance led to a fresh spell of snowfall in the mountains on December 25-26 and cold northwesterly winds are now sweeping through the plains after its retreat.</p>.<p>He said the wind chill factor -- a measure of the rate of heat loss from skin that is exposed to the air -- is also high.</p>.<p>The higher the wind speed during cold weather, the colder it feels on the skin if a person is outside.</p>.<p>Delhi clocked a top wind speed of 15 kilometers per hour (kmph) on Monday. Winds gusting up to 16 kmph are likely on Tuesday.</p>.<p>Dense to very dense fog prevailed in some parts of the National Capital Region (NCR), Haryana, Punjab, west Uttar Pradesh and north Rajasthan on Tuesday.</p>.<p>According to the IMD, "very dense" fog is when visibility is between 0 and 50 metres, 51 and 200 metres is "dense", 201 and 500 "moderate", and 501 and 1,000 "shallow".</p>.<p>In the plains, the IMD declares a cold wave if the minimum temperature dips to four degrees Celsius or when the minimum temperature is 10 degrees Celsius or below and is 4.5 notches below normal.</p>.<p>A "severe" cold wave is when the minimum temperature dips to two degrees Celsius or the departure from normal is more than 6.4 degrees Celsius.</p>