Sweden - Becky Ohlsen [26]
The visible aurora borealis, also called northern lights (norrsken), are caused by streams of charged particles from the sun and the solar winds, which are diverted by the Earth’s magnetic field towards the polar regions.
Because the field curves downward in a halo surrounding the magnetic poles, the charged particles are drawn earthward here. Their interaction with atoms in the upper atmosphere (about 160km above the surface) releases the energy creating the visible aurora (in the southern hemisphere, the corresponding phenomenon is called the aurora australis). During periods of high activity, a single auroral storm can produce a trillion watts of electricity with a current of one million amps.
The best time of year to catch the northern lights in Sweden is from October to March, although you may see them as early as August in the far north.
Midnight Sun & Polar Night
Because the earth is tilted on its axis, the polar regions are constantly facing the sun at their respective summer solstices, and are tilted away from it in the winter. The Arctic and Antarctic Circles, at latitudes 66°32’N and 66°32’S respectively, are the southern and northern limits of constant daylight on the longest day of the year.
The northern one-seventh of Sweden lies north of the Arctic Circle, but even in central Sweden the summer sun is never far below the horizon. Between late May and mid-July, nowhere north of Stockholm experiences true darkness; in Umeå, for example, the first stars aren’t visible until mid-July. Although many visitors initially find it difficult to sleep while the sun is shining brightly outside, most people get used to it.
Conversely, winters in the far north are dark and bitterly cold, with only a few hours of twilight to break the long polar nights. During this period, some people suffer from seasonal affective disorder (SAD), which occurs when they’re deprived of the vitamin D provided by sunlight. Its effects may be minimised by taking supplements of vitamin D (as found in cod liver oil) or with special solar spectrum light bulbs.
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The 25 historical regions (landskap) are denominators for people’s identity and a basis for regional tourist promotion, and are used throughout this book. The 21 counties (län) in Sweden form the basis of local government, and these county administrations are responsible for things like regional public transport (länstrafik) and regional museums (länsmuseum).
Geology
Between 500 and 370 million years ago, the European and North American continental plates collided, throwing up an impressive range of peaks called the Caledonian Mountains, which were as tall as today’s Himalayas. Their worn-down stubs form the 800km-long Kjölen Mountains along the border with Norway.
Parts of Skåne and the islands of Öland and Gotland consist of flat limestone and sandstone deposits, probably laid down in a shallow sea east of the Caledonian Mountains during the same period.
Lake Siljan, in the central south, marks the site of Europe’s largest meteoric impact: the 3km-wide fireball hurtled into Sweden 360 million years ago, obliterating all life and creating a 75km ring-shaped crater.
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WILDLIFE
Thanks to Sweden’s geographical diversity, it has a great variety of European animals, birds and plants.
LARGE PREDATORS
Sweden’s big carnivores – the bear, wolf, wolverine, lynx and golden eagle – are all endangered species. Illegal hunting carries a maximum prison sentence of four years. Most conflict between human and beast occurs in the Sami reindeer areas: compensation is paid to the Sami whenever predator populations in their lands increase.
Wolves and wolverines top Sweden’s most endangered list. Wolf numbers are slowly increasing, however: between 70 and 80 of these beautiful creatures now live in Sweden, mainly in Värmland and Dalarna.
The more solitary wolverine, a larger cousin of the weasel, inhabits