pyörremyrskystä

Pyörremyrsky is the Finnish word for a whirlwind or dust devil. These are small, rotating columns of air that form on warm, dry, and calm days. They are typically visible due to dust, sand, or debris being lifted from the ground. Pyörremyrskyt are not tornadoes; they are much weaker and form under different atmospheric conditions. They usually occur over land surfaces that have been heated by the sun.

The formation of a pyörremyrsky begins with uneven heating of the ground. As the ground heats up, pockets of warm air rise. If the air is stable and there is a slight updraft, this rising air can begin to rotate. The rotation is often initiated by small variations in wind direction or by turbulence. As the air column stretches and spins faster, it can pick up loose material from the surface, making it visible.

The size of a pyörremyrsky can vary greatly, from a few feet to over a hundred feet in height. Their wind speeds are generally modest, typically ranging from 20 to 60 miles per hour, although some can be stronger. They are usually short-lived, lasting only a few minutes before dissipating. While they can cause minor damage, such as scattering light objects, they are not considered a significant weather hazard. Pyörremyrskyt are a common phenomenon in many arid and semi-arid regions around the world, and they are frequently observed in Finland during warm, sunny periods, especially in open, dusty areas.