This is a phenomenon that occurs in St. Petersburg from late May to mid-July. It is an astronomical cyclic phenomenon, occurring at high latitudes (above 57 degrees N or S), consisting of the fact that at a certain period of the year, there is no complete darkness at night, dusk passes directly into dawn. During white nights, the sun's disc hides below the horizon, but quite shallowly. The phenomenon of light scattering in the upper layers of the atmosphere keeps the sky bright.
