Valonjuonteet

Valonjuonteet, often translated as "light lines" or "streaks of light," is a Finnish term used to describe a visual phenomenon observed in nature, particularly during clear, cold weather. It refers to a series of luminous, often faint, vertical or diagonal shafts of light that appear to emanate from bright light sources, such as streetlights, the moon, or distant stars.

This optical effect is caused by the diffraction of light as it passes through small, irregularly shaped ice crystals suspended in the atmosphere. These ice crystals, often referred to as ice prisms or diamond dust, act like tiny lenses or prisms, bending and scattering the light. The specific appearance of the valonjuonteet, including their color and intensity, depends on the size, shape, and orientation of these ice crystals, as well as the characteristics of the light source itself.

Valonjuonteet are most commonly seen in polar or sub-polar regions where atmospheric conditions conducive to the formation of ice crystals are frequent. The phenomenon is often associated with very cold temperatures, typically below -15 degrees Celsius, and a clear, calm atmosphere. While visually striking and often described as beautiful, valonjuonteet are a purely optical effect and do not indicate any changes in the light source or the atmospheric composition beyond the presence of ice crystals. They are a reminder of the intricate interplay between light and atmospheric particles.