Ilmajäämine

Ilmajäämine is a Finnish term that translates to "air freezing" or "ice formation in the air." It refers to the phenomenon of ice crystals forming directly from water vapor in the atmosphere, without first condensing into liquid water. This process is a key component of cloud formation and precipitation, particularly in colder climates.

The formation of ilmajäämine requires specific atmospheric conditions. There must be sufficient moisture in the air, typically in the form of invisible water vapor. Additionally, temperatures must be below freezing, and the presence of tiny particles called condensation nuclei is essential. These nuclei, which can be dust, salt, or other microscopic substances, act as surfaces upon which water vapor can deposit and freeze.

When these conditions are met, water vapor molecules attach to the condensation nuclei and transform directly into ice crystals. These ice crystals can grow in size by accreting more water vapor. As they become heavier, they can fall from the clouds as various forms of frozen precipitation, such as snow, ice pellets, or graupel. The specific type of precipitation depends on factors like the temperature profile of the atmosphere and the growth process of the ice crystals. Understanding ilmajäämine is crucial for meteorologists in forecasting weather patterns, especially those involving snow and ice.