sääilmiön

Sääilmiö is a Finnish term meaning "weather phenomenon." In meteorology it refers to any observable condition or event in the atmosphere. Weather phenomena arise from interactions among air masses, moisture, temperature, pressure, and solar radiation, and they can be short lived or long lasting.

They are often grouped into categories such as atmospheric dynamics (fronts, storms, wind shifts), precipitation (rain, snow, hail), clouds and cloud formation, and optical or electrical phenomena (rainbows, halos, auroras, lightning). Observations include ground measurements, weather radar, satellites, and numerical models that forecast their development.

Common examples include fog, thunderstorms, snow squalls, and rainbows; halos around the sun or moon caused by ice crystals in the upper atmosphere; auroras at high latitudes; and virga, precipitation that evaporates before reaching the ground. Some phenomena involve rapid changes in weather conditions, while others are more persistent or regional in nature.

The study of weather phenomena aims to explain how they form, improve forecasts, and assess risks to people, property, and agriculture. Geographic location and season influence which phenomena are most common. Weather services use standardized terms and warnings to communicate potential hazards associated with notable weather phenomena, providing information that supports safety and planning.