The Polar Night

Winter is the coldest season of the year in temperate climate, between autumn and spring.

At the winter solstice, the days are shortest and the nights are longest, with days lengthening as the season progresses after the solstice.

Meteorological winter is the season having the shortest days and the lowest average temperatures, which have the coldest weather. This corresponds to the months of November, December and January in the Northern Hemisphere. The coldest average temperatures of the season are typically experienced in January in the Northern hemisphere.  

 

The polar night occurs when the night lasts for more than 24 hours. This only occurs inside the polar circles. The opposite phenomenon, when the sun stays above the horizon for a long time is called the polar day, or midnight sun.

A common misconception is that the shortest day is totally dark at each point where the midnight sun occurs inside the polar circle. In places very close to the poles this is true, but in regions that are located at the inner border of the polar circles where midnight sun is experienced, this is not true. Due to twilight, these regions experience polar twilight instead of the polar night. In fact, polar regions typically get more twilight throughout the year than equatorial regions.

In regions inside the polar circles, the length of the time when the sun is below the horizon varies from 20 hours at the Arctic Circle and Antarctic Circle to 179 days at the Poles. However not all this time is classified as polar night, since there may be plenty of sunlight because of refraction. Also, one might notice that the time when the sun is above the horizon at the poles is said to be 186 days. The asymmetry in numbers is because the time when the sun is partially above the horizon is counted towards the "daytime".

The Winter Solstice occurs exactly when the earth's axial tilt is farthest away from the sun at its maximum of 23° 26'. Though the Winter Solstice lasts an instant in time, the term is also colloquially used like Midwinter to refer to the day on which it occurs. For most people in the high latitudes this is commonly known as the shortest day and the sun's daily maximum position in the sky is the lowest. The seasonal significance of the Winter Solstice is in the reversal of the gradual lengthening of nights and shortening of days. The Winter Solstice is also the shortest day or lowest sun position for people in low latitudes located between the Tropic of Cancer and the Tropic of Capricorn Depending on the shift of the calendar, the winter solstice occurs some time between December 21 and December 22 each year in the Northern Hemisphere.

 

 

  

  

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