Sunlight hours

Expeditioner with camera tripod over shoulder walks in front of rising sun
An expeditioner watches as the sun appears over the horizon at Davis, for the first time in six weeks (Photo: Jeff R)
Sunset and penguins at DavisSolar pillar and nacreous clouds Sunset at Casey RangesA double solar halo Towering sun through the ice-laden atmosphere

How much daylight is there in Antarctica during summer and winter?

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 there is 24-hour sunlight.

The polar circles (both the Antarctic Circle at 66°33' S and Arctic Circle at 66°33' N) mark the latitude beyond which the sun remains completely below the horizon throughout the day on Midwinter’s Day and completely above the horizon on Midsummer’s Day. As you move closer to the poles, the periods of winter darkness and summer daylight increase.

Compare the graphs below for Mawson and Davis. Davis is located further south than Mawson and therefore the sun does not rise here for a longer period of time during winter. At the poles themselves, the seasonal changes are even more pronounced: 24 hours of daylight occur for several months over summer, while there is complete darkness for several months during winter.

The diagrams below show how the length of day changes as you travel south to north from South Pole to Dome A, Davis, Mawson, Casey, Macquarie Island, Heard Island and Kingston, Tasmania.

South Pole sunlight chart, showing total darkness around the middle of the year, and full sunlight at the start and end of the year
Dome A sunlight chart, showing days of constant sunlight from October–February, and the short days in the middle of the year: never leaving astronomical twilight
Davis sunlight chart, showing the short days in the middle of the year: never leaving civil twilight
Mawson sunlight chart, showing the short days in the middle of the year (never leaving civil twilight)
Casey sunlight graph, showing very short days in the middle of the year
Macquarie Island sunlight chart, showing significantly shorter days in the middle of the year.
Heard Island sunlight chart, showing significantly shorter days in the middle of the year.
Kingston Tasmania sunlight chart, showing significantly shorter days in the middle of the year. Each day has some amount of ‘true’ day and night.

Definitions

Civil twilight
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, and under good weather conditions terrestrial objects will still be visible.
Nautical twilight
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, but the horizon is still visible, even on a moonless night.
Astronomical twilight
This occurs when the sun is between 12° and 18° below the horizon. There is no colour in the sky during astronomical twilight.

This animation shows the changing length of the days for places at different locations of latitude. At more southerly latitudes the change in length of day from summer to winter is more extreme.

[Video]

Light levels animation

Video transcript

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This page was last updated on 10 April 2015.