How much daylight is there in Antarctica during summer and winter?
As you move closer to the poles, the periods of winter darkness and summer daylight increase. The polar circles (both the Antarctic Circle at 66°34′ S and Arctic Circle at 66°34′ N) mark the latitude beyond which the sun remains completely below the horizon on Midwinter’s Day, and completely above the horizon on Midsummer’s Day.
On Antarctica’s coast, where our stations are located, there are usually a couple of weeks in mid-winter (around 21 June) when the sun does not rise, and a couple of weeks in summer around Christmas when the sun does not set.
Compare the graphs below for Mawson and Davis. Davis is located further south than Mawson, so it gets less sunlight hours during winter. At the poles themselves, the seasonal changes are even more pronounced. 24-hour daylight occurs for several months over summer, while in winter there is complete darkness for several months.
The diagrams below show how the length of day changes as you travel north, from the South Pole to Dome A, Davis, Mawson, Casey, Macquarie Island, Heard Island, and finally, Kingston in Tasmania.
This occurs after sunset or before sunrise when the centre of the sun is up to 6° below the horizon. At this time, the brightest stars are normally visible. Under good weather conditions, terrestrial objects will still be visible.
This occurs when the sun is between 6° and 12° below the horizon. At this time, only the general outlines of ground objects may be visible. The horizon is still visible, even on a moonless night.
This occurs when the sun is between 12° and 18° below the horizon. There is no colour in the sky during astronomical twilight. It is not possible to make out the horizon.