Sunlight controls the pace in Arctic Ltd, even when the sun does not shine. In summer when the light is on for 24 hours a day, the area is teeming with life, production is at its maximum, and hired hands from southern parts arrive in their thousands. In winter when the light is off, all activity is at a minimum and only the most essential maintenance work is carried out.

The angle of the earth's axis means that the further north you travel, the longer the polar night lasts. Fortunately, the midnight sun also lasts longer. As the table shows, the polar night at the North Pole lasts from about 25 September to 18 March, all of six months. On the other hand, there is midnight sun from about 20 March to 23 September, also six months. Quite a good change!

When the polar night is in charge, it is dark more or less all the 24 hours, but when the light returns, it does so to the full. Svalbard has four months of midnight sun, and it is vital to utilise the light to the maximum then for growth and reproduction. There are several reasons why the arctic regions remain cold even though the sun can shine all day and all night long. As the figure of the earth shows, the rays of the sun have a long way to travel through the atmosphere to reach the Arctic, much further than to the Equator. Much of the radiation will therefore be stopped in the atmosphere and less gets through to the arctic regions. Moreover, when the sunlight shines on the white ice much of the radiation is reflected back to the atmosphere again without contributing heat.

Did you know... information icon Even though the sun is absent during the polar night in the Arctic, it still helps to produce light in the sky, the Northern Lights (Aurora Borealis). The sun emits electrically charged particles and they are influenced by the earth's magnetic field which directs them round the magnetic poles. The particles collide with air molecules in the upper atmosphere, and we can see this as lights in the sky. These lights can be seen near both poles, in the Arctic and the Antarctic. They are called the Southern Lights (Aurora Australis) in the Antarctic.

Periods of midnight sunThe table shows the periods of midnight sun (polar day) and polar night at some places in the Arctic and on the Norwegian mainland.
Illustration: NPI
The sunlight's path to the earthSunlight reaches the Earth in this way. As the illustration shows, the rays have much further to travel to reach the polar regions, and the angle of the Earth's axis also means that the area north of the Arctic Circle experiences the polar night in winter.
Illustration: Audun Igesund, NPI