polarnoci

Polarnoci (polar night) is the period in winter when the Sun remains below the horizon for an extended stretch at high latitudes. It occurs in the polar regions north of 66.5 degrees north (the Arctic Circle) and south of 66.5 degrees south (the Antarctic Circle). The effect results from the tilt of Earth's axis, about 23.5 degrees, relative to its orbit around the Sun, which causes the Sun to stay below the horizon for days to months as winter progresses.

The duration of polarnoci increases with latitude. Near the polar circles, the period of darkness can last from several days to several weeks, while at the poles it spans roughly six months. Some days during polarnoci still feature twilight, as the Sun remains just below the horizon, producing civil or nautical twilight rather than full darkness. In the most extreme northern and southern latitudes, the nights are effectively continuous for extended stretches.

During polarnoci, daylight is greatly reduced, and weather often reinforces the darkness with cloud cover and cold temperatures. The phenomenon is commonly associated with atmospheric displays such as auroras, especially when skies are clear. Wildlife and human activity adapt to prolonged darkness, employing artificial lighting, altered routines, and cultural traditions in Arctic and Antarctic communities. Polarnoci is the counterpart to polar day (midnight sun), when the Sun remains above the horizon for extended periods.