twilight Polar twilight occurs in areas that are located at the inner border of the polar circles, where the Sun will be on or below the horizon all day on the winter solstice. There is then no true daylight at the solar culmination, only civil twilight. This means that the Sun is below the horizon, but by less than 6°. During civil twilight, there may still be enough light for most normal outdoor activities because of light scattering by the upper atmosphere and refraction. Street lamps may remain on and a person looking at a window from within a brightly lit room may see their reflection even at noon, as the level of outdoor illuminance will be below that of many illuminated indoor spaces. It occurs at latitudes between 67°24’ and 72°34’ North or South, when the Sun does not rise, only civil twilight visible. Northern Hemisphere: 68° North: December 9 to January 2 69° North: December 1 to January 10 70° North: November 26 to January 16 71° North: November 21 to January 21 72° North: November 16 to January 25 Southern Hemisphere: 68° South: June 7 to July 3 69° South: May 30 to July 11 70° South: May 24 to July 18 71° South: May 19 to July 23 72° South: May 14 to July 27 Sufferers of seasonal affective disorder tend to seek out therapy with artificial light, as the psychological benefits of daylight require relatively high levels of ambient light (up to 10,000 lux) which are not present in any stage of twilight; thus, the midday twilights experienced anywhere inside the polar circles are still "polar night" for this purpose. Civil polar night The civil polar night period produces only a faint glow of light visible at midday. It happens when there is no civil twilight and only nautical twilight occurs at the solar culmination. Civil twilight happens when the Sun is between 0 and 6° below the horizon, and civil night when it is lower than that. Therefore, the civil polar night is limited to latitudes above 72° 34', which is exactly 6° inside the polar circle. Nowhere on mainland Europe is this definition met. On the Norwegian territory of Svalbard, however, civil polar night lasts from about 11 November until 30 January. Dikson, in Russia, experiences civil polar night from December 6 to January 6. During dense cloud cover places like the coast