sileilläs

Sileilläs is a Finnish name referring to a type of ice-related weather phenomenon. It is characterized by a prolonged period of calm weather accompanied by temperatures below freezing, resulting in sustained ice formation on bodies of water. During a sileilläs, the air near the surface of the water is cooled rapidly, causing the water to freeze despite air temperatures only being near or slightly below freezing.

In Finnish culture, sileilläs is often associated with unusually prolonged periods of ice cover on lakes and other water bodies during late winter or early spring. The sileilläs is typically preceded by a longer, colder period of weather that causes extensive ice formation, after which the calm conditions persist for several days or even weeks. During this time, the ice cover may become increasingly fragile, leading to periods of rapid deterioration.

Sileilläs is considered a rare weather event in many regions. In parts of Finland, it has been known to occur every few years on average, although specific instances can vary from one region to another. The term sileilläs itself comes from Finnish and roughly translates to 'kept calm' or 'cold and calm', acknowledging the persistent, uneventful conditions that distinguish this phenomenon.