>>18081970
Btw Blonde hair is also associated with night/darkness, as it is a direct result of the mutation that causes very fair skin. In the Scandinavian region and surrounding areas, where night/winter lasts six months due to being near the planet's north pole, where the sun doesn't reach its light directly/completely as at the Equator, one can become deficient in Vitamin D, which humans obtain from the sun, due to excess Melanin, which reflects UV rays, while fair skin absorbs sunlight and provides more Vitamin D to the body. This gave fair-skinned people a selective advantage, which caused their numbers to increase proportionally in the region.

>Polar night is a phenomenon that occurs in the northernmost and southernmost regions of Earth when the Sun remains below the horizon for more than 24 hours. This only occurs inside the polar circles. The opposite phenomenon, polar day or midnight sun, occurs when the Sun remains above the horizon for more than 24 hours

>There are multiple ways to define twilight, the gradual transition to and from darkness when the Sun is below the horizon. "Civil" twilight occurs when the Sun is between 0 and 6 degrees below the horizon. Nearby planets like Venus and bright stars like Sirius are visible during this period. "Nautical" twilight continues until the Sun is 12 degrees below the horizon. During nautical twilight, the horizon is visible enough for navigation. "Astronomical" twilight continues until the Sun has sunk 18 degrees below the horizon. Beyond 18 degrees, refracted sunlight is no longer visible. True night is defined as the period when the sun is 18 or more degrees below either horizon

>Since the atmosphere refracts sunlight, polar day is longer than polar night, and the area that experiences polar night is slightly smaller than the area that experiences polar day. The polar circles are located at latitudes between these two areas, at approximately 66.5°