Ljuslinjer

Ljuslinjer, also known as light lines or light trails, are optical phenomena that appear in the sky as a result of the scattering of light by ice crystals in the atmosphere. These lines are typically seen during the twilight hours, when the sun is below the horizon but its light is still illuminating the upper atmosphere. The most common type of ljuslinjer is the circumzenithal arc, which appears as a bright, colorful arc above the zenith, the point directly overhead. Another type is the circumhorizontal arc, which is a horizontal arc that can sometimes be seen during the day.

Ljuslinjer are formed when sunlight enters a hexagonal ice crystal and is refracted and reflected internally before exiting the crystal. The specific angles at which this occurs determine the type of ljuslinjer that is observed. These phenomena are more commonly seen in cold regions, where the necessary ice crystals are more likely to be present in the atmosphere. They are also more visible in clear, dry air, as moisture and clouds can scatter the light in different ways, obscuring the ljuslinjer.

Observing ljuslinjer can be a fascinating experience, as they often appear as vibrant, colorful bands of light in the sky. However, they are relatively rare and require specific atmospheric conditions to be visible. Photographing ljuslinjer can be challenging due to their fleeting nature and the need for precise timing and camera settings. Despite these challenges, they remain a popular subject for photographers and sky watchers alike.