Why doesn't it get dark in St Petersburg Russia during June and July - even though the sun actually sets?

Answer 1

It doesn't get dark in St Petersburg, Russia during June and July because of the city's location towards the North Pole.

There is still light (called "twilight") after sunset, because of atmospheric effects. That's refraction and, most importantly, the scattering of sunlight by the upper atmosphere.

In the summer, at high latitudes, the Sun is never far below the horizon.

Answer 2

St. Petersburg, Russia experiences the phenomenon of "White Nights" in June and July due to its high latitude. During this time, the sun only dips below the horizon briefly, keeping the sky bright throughout the night. This unique phenomenon occurs because St. Petersburg is located near the Arctic Circle, where the sun does not fully set during the summer months.

Answer 3

Astronomical twilight, the first of the three stages of twilight before sunrise and the last stage after sunset, begins before sunrise and ends after sunset when the sun is 18 degrees below the horizon. At the time of the June solstice everywhere north or the Arctic Circle is in daylight. If you are standing on the point on the Arctic Circle where the local mean time is midnight at the moment of the solstice, the sun will be on the horizon (due north). Therefore everywhere within 18 degrees of the Arctic Circle will have twilight all night that night, which is usually the 21st of June. Since the Arctic Circle is 66.56 degrees north latitude, everywhere north of 48.56 degrees north latitude will have at least one night in which twilight doesn't end. The closer you are to the Arctic Circle, the more nights of unending twilight you will have, and the brighter those twilights will be.