White nights: magical sketches of the "Northern Venice"

White nights have long become a visiting card and one of the main attractions of St. Petersburg. This unusual natural optical phenomenon is observed in the city on the Neva River every year from June 11 to July 2. At this time, the center of the solar disk descends at midnight below the horizon line by no more than seven degrees, which causes a sufficiently high level of illumination for this time of day.

The geography of this unusual natural effect is quite extensive. White nights are observed at the beginning of the summer period in both hemispheres at latitudes in excess of sixty degrees. But in our minds they have long become a symbol of St. Petersburg. At this time, the city does not seem to be asleep, watching the magic etudes of nature. There are many concerts, festivals, performances. It seems that the whole city is immersed in the magic of natural effects. At this time a huge number of tourists come here, as well as stars of music and cinema from around the world.

Every year in northern Palmyra in June there is a rock festival with a very symbolic name "White Nights in Petersburg". Also at this time, an international film competition is held here, where films made during the year are shown. Days of white nights in the largest non-capital city of Europe are marked by an extremely intense and intense cultural life. This is a magical holiday, presented by nature itself, which is also one of the tourist baits of the city on the Neva. St. Isaac's Cathedral on a white night looks especially impressive.

What is this phenomenon from the astronomical point of view and what is the mechanism of its formation? The term "white nights" is usually used to denote the qualitative characteristic of twilight, for which a sufficiently high level of natural illumination is characteristic . In fact, in the period close to the summer solstice in the Northern Hemisphere, the evening twilight closes with the morning. The process of motion of our planet in its orbit is associated with a change in the angle of inclination of the earth's axis by a certain number of degrees. As a consequence, the North Pole moves to the perihelion point, which is accompanied by a practically perpendicular drop in the sun's rays on the surface of the planet in the polar regions. This causes such unusual optical effects, which came into use as "white nights".

Such a natural phenomenon in Russia is typical not only for St. Petersburg, but also for Murmansk, Norilsk, Vorkuta, Cherepovets, Vologda, Magadan, Nizhnevartovsk, Khanty-Mansiysk, Nefteyugansk, Surgut, Yakutsk, Arkhangelsk and many more cities and regions to the north Sixtieth parallel. In addition, this effect was observed in latitudes closer to the equator, which was caused by the fall of the Tunguska meteorite. After that, in the territory of many European countries and in Russia it was possible to observe various optical anomalies, among which are so-called bright dawns and white nights, which are completely uncharacteristic for these regions.

Outside of Russia, this phenomenon is also not so rare. Finland, for example, is generally considered the end of the white nights. Also this natural optical effect is characteristic for northern Sweden, Iceland, Norway, the polar regions of Canada, Greenland and even Estonia. In the UK, white nights can be seen on the Orkney Islands.