lentotuhkaa

Lentotuhka is a Finnish term used to describe volcanic ash clouds that form when volcanic eruptions eject fine tephra into the atmosphere. The term is commonly used in discussions of aviation safety in Finland and in meteorological and geological contexts to denote airborne ash capable of affecting aircraft operations. Lentotuhkaa consists of tiny, abrasive glassy particles released during eruptions, often accompanied by pumice fragments and gas.

The ash particles are typically less than a few millimeters in diameter, with the finest fractions capable of remaining suspended in the atmosphere for hours to days. Once injected, the ash cloud can be carried by winds over long distances and to high altitudes, commonly reaching between 5 and 15 kilometers, and in powerful eruptions potentially up to 20–30 kilometers. The cloud’s appearance, thickness, and geographic reach depend on eruption style, plume height, atmospheric stability, and wind patterns. Interaction with weather systems can cause complex dispersion, entrainment of ambient moisture, and settling of particles over time.

For aviation, lentotuhkaa represents a major hazard. Volcanic ash can abrade and erode aircraft surfaces, melt and clog components in jet engines, and reduce visibility and sensor performance. International aviation authorities monitor ash plumes and issue advisories, leading to route diversions, holds, or grounding of flights when ash concentrations are uncertain or dangerous. Monitoring relies on satellites, ground-based observations, and dispersion models coordinated by volcanic and meteorological agencies. Notable events, such as the 2010 Eyjafjallajökull eruption, illustrated the broad impact ash clouds can have on air travel and economy.