Explaining Polar Nights
Can you imagine living in a place with six months of darkness? If you have been to polar bear land in the high Arctic, or research stations around the South Pole, you may be familiar with this phenomenon. Polar nights, as well as their opposite extreme called polar days (midnight sun with 24 hours of daylight) occur in the Earth’s polar regions. And when it comes to polar day and night, the Northern and Southern hemispheres are polar opposites! When the Arctic experiences their darkest day of the year in December, the polar day is happening within the Antarctic Circle. Why do polar nights exist and where can you see them? Explore the dark side of the polar regions and find out all about polar nights!
Polar Night Occurrence
If you’ve ever been to the polar regions during the winter months, you likely experienced the polar night. In the middle of the day, you’ll see the stars and moon on the horizon. This period of darkness is perfect for seeing northern lights in the sky. In winter, the sun sets and stays below the horizon for up to 11 weeks if you are located directly at one of the poles. The length of polar nights depends on your location. In the summer months, the polar regions in contrast get 24 hours of daylight, during the polar day.
The polar night occurs due to the Earth’s axis tilt away from the sun during winter. With the Earth tilted, the sun cannot reach the respective polar region at that time of the year. This happens in the Northern and Southern Hemisphere and you can experience the most intense polar nights at the South and North Pole.
Polar twilight occurs when the light scattering of Earth’s upper atmosphere refracts sunlight that illuminates the lower atmosphere. Twilight comes in different stages, depending on the sun’s position below the horizon:
- Civil twilight (the sun is less than 6 degrees below the horizon)
- Nautical twilight (the sun is between 6 and 12 degrees below the horizon)
- Astronomical twilight (the sun is between 12 and 18 degrees below the horizon)
Where Can You See the Polar Night?
Polar nights occur inside the polar circles. In the Northern Hemisphere, you can experience the polar night in areas above 66 degrees latitude north. The higher the latitude, the longer it stays dark. In the Arctic, these days without daylight are visible in areas above the Arctic Circle such as northern Norway, Canada, the United States (Alaska), Greenland, Finland, Russia and Sweden. In the south, you can experience them within the Antarctic polar circle. The length of the polar nights and when they begin depend on where you find yourself. In Svalbard they start around mid-November.
It Starts With the Equinox
Polar nights in the Arctic begin at the time of the autumnal equinox in September, with the sun setting. For the next six months that follow, the sun stays below the horizon and you’ll experience darkness even during the daytime. The winter darkness hits its peak during the winter solstice (or December solstice). At the North Pole, December 21 is considered the darkest time of the year. The polar astronomical night is a period during the polar night observed only above 84 degrees south or north, where it gets very dark without the presence of twilight. The only inhabited place in the world to experience this is the Amundsen-Scott South Pole Station.
While the winter above the Arctic Circle is very cold, consider visiting during this period for prime opportunities to see the aurora borealis! And don’t worry, in most places it doesn’t get pitch black. Don’t expect true daylight, but civil twilight during this time will give you enough light to go about normal outdoor activities such as dog sledding, snowmobiling or skiing.
The Light Returns
After the winter solstice, the polar night slowly recedes. In December and January, you can experience the blue hour, a little break of the polar night when skies turn blue between 10am and 3pm. With the vernal equinox in March, the sun rises, with daylight increasing gradually until the summer solstice on June 20. During this time (within the polar circles), you can experience polar days with up to 24 hours of daylight and the midnight sun.
It’s Reversed in the Southern Hemisphere
When there’s light in the Northern Hemisphere, it’s night in the Southern Hemisphere. When there’s winter in the Arctic, it’s summer in the Antarctic. And the same goes for the polar day and polar night, they occur opposite to each other in the north and south.
No True Polar Nights at the Polar Circle
Even when the polar night begins, it doesn’t mean that you can experience it exactly at the polar circles. For example, in Gällivare (Sweden), located around 100km (60 miles) north of the Arctic Circle, you won’t experience full 24-hour dark polar nights, even in mid-December. Expect twilight rather than a full polar night.
But why do polar nights elude the direct polar circle area? The definition of the polar circles is part of the problem, marking the latitude where the center of the sun touches the horizon, but the actual sunset and sunrise are defined by the visibility of the sun’s upper edge. In short, directly at the circle you may still be a little too low in latitude to get the full spectrum of darkness. Also due to refraction, sunlight is visible above the horizon minutes before it actually rises and after it sets. That’s why even in regions inside the polar circles you can see various stages of twilight (usually around noon).
Let There Be Light – Even During Polar Nights
Experiencing a polar night may sound romantic, with beautiful northern lights on the horizon, above the beautiful tundra landscapes and surrounded by Arctic nature. But once six months of darkness become part of your life, you may see how difficult it is to live in such conditions. For visitors and those not used to it, the normal sleeping routine may be disturbed. In some regions, such as Svalbard, climate change adds to the depressing dark months with reduced snow cover and increased winter rain, further challenging locals in dealing with the already tough winter conditions.
One community in Rjukan, Norway took matters into its own hands and put an end to its deprivation of sunlight. In addition to being so far north, the town is also surrounded by high peaks, which further obstruct direct rays of light, especially during the polar night period. To bring light into the dark days of winter, Rjukan set up three glass mirrors, which follow the sun’s movement and reflect it to patches in town, where locals gather and take a sunny rest during the cold winter. This innovative contraption harvests about 85% of the available sunlight.
FAQ
How long does the polar night last?
The length of the polar night period depends on where you are in the polar circle zone. Once the sun sets on the horizon (in autumn in the Arctic and spring in the Antarctic), it can be days to several months until it returns. As an example, at the North Pole darkness may last for up to six months, while the polar night in Longyearbyen (Svalbard) lasts for around three months (November, December and January).
What happens during the polar night?
During the period of the polar night, the sun does not rise above the horizon for more than 24 continuous hours. The closer you are to the pole, the longer the polar night lasts.
Which countries experience a polar night?
You can experience the polar night and polar day in parts of Norway, Canada, the United States (Alaska), Greenland, Finland, Russia, Sweden and Antarctica. Territories located inside the polar circles experience this phenomenon. Exactly at the polar circles, you may experience civil twilight rather than complete darkness.
What is the difference between a polar day and a polar night?
During the polar day, the sun does not set for more than 24 continuous hours, while the polar night refers to the period when the sun does not rise for more than 24 continuous hours. Since sunlight is refracted by the Earth’s atmosphere, polar days are longer than polar nights and the area in which the polar night can be experienced is a bit smaller than the area of where you can see the midnight sun.