hyytymille

Hyytymille is a Finnish word that translates to "frost flower" in English. It refers to a delicate ice formation that can be observed on thin layers of ice, typically on freshwater bodies like lakes and ponds, during very cold and calm conditions. These formations are not actual flowers but are created by the sublimation of ice.

When the temperature of the ice is below freezing and the surrounding air is also cold and humid, but not so cold that the moisture in the air freezes instantly, water vapor can transition directly from a gaseous state to a solid state (ice) onto the surface of the existing ice. This process, called deposition or desublimation, causes ice crystals to grow outward from the ice surface, often forming intricate, petal-like structures.

The appearance of hyytymille is highly dependent on atmospheric conditions, including temperature, humidity, and wind. Calm weather is crucial, as even a slight breeze can disrupt the delicate crystal growth. The formations are fragile and melt quickly when temperatures rise or if disturbed. They are most commonly seen in the early stages of winter, before the ice thickens significantly. Observing hyytymille is considered a beautiful natural phenomenon, often associated with the quiet stillness of winter landscapes.