White nights have long been 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 every year from June 11 to July 2. At this time, the center of the solar disk falls at midnight below the horizon no more than seven degrees, which leads to 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 exceeding sixty degrees. But in our minds they have long become a symbol of St. Petersburg. At this time, the city does not seem to sleep, watching the magical sketches of nature. It hosts many concerts, festivals, and 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 music and cinema stars from around the world.
Every year in June in northern Palmyra, a rock festival is held with the very symbolic name “White Nights in Petersburg”. Also at this time, an international film contest is held here, where films shot over the course of the year are shown. The days of white nights in Europe's largest non-capital city are marked by an extremely eventful and intense cultural life. This is a magical holiday, presented by nature itself, which is also one of the tourist lures of the city on the Neva. St. Isaac's Cathedral on a white night looks especially impressive.
What is this phenomenon from an astronomical point of view and what is the mechanism of its formation? The term "white nights" is used to denote the quality characteristic of twilight, for which a fairly high level of natural light is characteristic. In fact, in a period approaching the summer solstice in the Northern Hemisphere, evening twilight merges with morning twilight. The process of movement 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 result of this, the North Pole moves to the point of perihelion, which is accompanied by an almost perpendicular incidence of sunlight on the planet's surface in the polar regions. This causes such unusual optical effects that came into use under the name “White Nights”.
Such a natural phenomenon in Russia is characteristic not only of St. Petersburg, but also of Murmansk, Norilsk, Vorkuta, Cherepovets, Vologda, Magadan, Nizhnevartovsk, Khanty-Mansiysk, Nefteyugansk, Surgut, Yakutsk, Arkhangelsk and many more cities and regions located north of sixtieth parallel. In addition, such an effect was observed at 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, including the so-called bright dawns and white nights, which are completely uncharacteristic of these regions.
Outside of Russia, this phenomenon is also not uncommon. Finland, for example, is generally considered the edge of white nights. This natural optical effect is also characteristic of 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.
