Windstille

Windstille, literally wind silence in German, is a meteorological term describing a period of unusually light or nearly absent wind. In practical terms, it corresponds to calm conditions, often associated with a Beaufort value of 0 (no wind) and only very light air around the vicinity of 1–2 on the scale. Windstille can occur in different atmospheric regimes, most commonly under a large, persistent high-pressure system that suppresses horizontal air movement, or within settled anticyclonic air masses. Local windlessness can also emerge in coastal areas during transitions between sea breezes and land breezes, or in mountain valleys where airflow becomes stagnant.

Causes and patterns vary by region but share the common feature of a weak pressure gradient over the area. Forecasting windstille relies on synoptic weather maps, surface pressure analyses, and wind fields produced by numerical weather prediction models. Wind measurements from anemometers help verify calm periods, with speeds near or below 1 meter per second (0–2 mph) often cited as calm.

Effects and significance vary with context. For sailors, windstille historically meant becalmed conditions that stalled movement and required waiting for wind. In agriculture and ecology, calms can influence pollination and local microclimates. Windstille is a notable indicator of stable weather, contrasting with windier transitions associated with passing fronts or cyclones.

See also: calm, doldrums, sea breeze, zephyr.