IIstjärnor

Iistjärnor is a Swedish term that translates to "ice stars" or "ice flowers." It refers to a fascinating natural phenomenon that occurs in extremely cold and humid conditions, typically on frozen surfaces like windows, lakes, or rivers. These delicate, crystalline structures form when water vapor in the air rapidly freezes onto a surface. The resulting formations often resemble intricate starbursts, ferns, or feathers, hence the poetic name.

The formation of iistjärnor requires specific atmospheric conditions: temperatures well below freezing (often -15°C or colder) and high humidity. As moist air comes into contact with the supercooled surface, the water molecules instantly transition from gas to solid, forming ice crystals. The shape and pattern of the iistjärnor are influenced by factors such as air currents, the temperature gradient, and the surface onto which they are forming.

These ephemeral ice sculptures are most commonly observed during winter months in regions with prolonged periods of extreme cold. They are a beautiful, though often overlooked, manifestation of the physical processes that occur in nature. While they can be found on various frozen surfaces, they are particularly striking when seen on windowpanes, creating natural works of art that disappear as the temperature rises or the sun's rays hit them.