Radiant Clouds in the June Night Sky

Up until mid-July 2025, a fascinating type of cloud known as night-glowing clouds can be seen across central Europe. These clouds are visible only during dawn or dusk, as they are lit up by the sun, which is positioned far below the horizon during these times. Throughout the day, these high-altitude clouds are completely invisible. At nighttime, the glowing clouds can be most frequently seen in the weeks surrounding the summer solstice, which falls on Saturday, June 21, 2025. This is when the delicate silver veils of stunning filamentary clouds high up in the mesosphere become visible to us. Unlike regular clouds that usually form at heights no more than 15 kilometers, the night-glowing clouds are located much higher, hovering at about 85 kilometers above the Earth, particularly around the Arctic Circle.

The stunning appearance of these nighttime glowing clouds is closely linked to meteor dust and fluctuations in solar activity. These clouds are created by the buildup of ice crystals on tiny dust particles that exist at this altitude, which are left behind by meteoric dust, volcanic eruptions, or even pollution from industrial activities. The phenomenon is best observed between 10 p.m. and midnight, or in the early morning between 2 and 4 a.m., primarily appearing over the northwest to northeast horizon. Their appearance cannot be predicted, so it is essential to keep an eye on the directions where they might show up during these times. Additionally, ensure that your view of the northern horizon is as clear as possible to increase your chances of spotting them.