This is because December 21st marks the astronomical start of winter for the northern hemisphere with the winter solstice. During this season the days are shorter than the nights, and as we get closer to the North Pole, we will have up to 24 hours of darkness.
That is why on December 21st, the sun is not visible for 24 hours and the next days (the closer it is to the north pole) it will stay that way. Therefore, the inhabitants of this area will have longer periods of darkness.
Explanation: Dictators like Adolf Hitler denied religious freedoms to the Jewish race and killed millions of innocent Jews. A more Modern example would be Kim Kong Un. Who oppresses his people and forces them to believe that the Kim family are basically gods. With communism, a good example would be the Xinjian conflict where the Uiger people are opressed by the Chinese government and are not allowed to believe in there traditional religions and are sent to "reeducation camps" to be forced into the "Chinese way of life".
An ocean gyre is a large system of circulation of oceanic currents, by the global winds and global forces created by the rotation of the planet on its axis.
These gyres help in driving the conveyor belt that circulates the oceanic water throughout the planet. Various types of Oceanic Gyres are found on the globe like tropical, subtropical, and subpolar gyres.
The tropical gyres are less developed ad tend to be found in the east to west, north to a south extent. Formed by pacific equatorial currents system. the subtropical gyre is a system of the high-pressure zone that moves in a clockwise direction from the northern hemisphere, and anticlockwise in the southern hemisphere.
The subpolar gyres found at a height of 60 degrees, consists of clockwise circulation of winds in low-pressure areas around the northern hemisphere. Like the Aleutian and Icelandic low.
The recent development of climate change and the unequal distribution of heat floes have accelerated the process of the formation of gyres.