Merituulet

Merituulet is a Finnish term describing winds that originate from the sea and influence coastal weather. In meteorology the concept typically refers to sea-breeze circulations along coastlines, including the daytime onshore flow from sea to land and, outside the main sea-breeze period, related coastal wind patterns shaped by marine conditions.

Formation and dynamics: Merituulet arise from differential heating between land and sea. During the day, land heats quickly, causing air to rise near the coastline and creating a low-pressure area along the shore. Cooler air from the sea moves onshore to replace the rising air, producing an onshore wind from sea to land. At night, the land cools faster than the sea, and a land breeze can develop, potentially reversing or weakening the daytime merituulet. The strength and inland reach of merituulet depend on coastal topography, sea-surface temperature, atmospheric stability, and larger-scale weather patterns; the Coriolis effect can further influence the wind direction as air moves inland.

Impacts: Merituulet contribute to moderating daytime coastal temperatures by bringing cooler air from the sea, increasing humidity, and promoting cloud formation and fog near the coast. They affect local microclimates, coastal weather forecasting, and maritime operations, including shipping, aviation, and the siting and operation of wind-energy installations.

See also: sea breeze, coastal meteorology, land breeze.