Editing Polar night (section)

==Description==
{{Unreferenced section|date=October 2022}}
[[File:Ruka Cottage (8328890447).jpg|thumb|right|Civil polar twilight in [[Ruka, Finland]] at noon in December]]
The length of polar night varies by latitude from 24 hours just inside the polar circles to 179 days at the poles. As there are various kinds of [[twilight]], there also exist various kinds of polar twilight that progress towards true polar night. Each kind of polar night is defined as when it is darker than the corresponding kind of twilight. The descriptions below are based on relatively clear skies, so the sky will be darker in the presence of dense clouds.