Gap Winds
this increasing temperature differential, the surface pressure is relatively higher over the ocean than overland, and thus, sea air begins to flow inland. This thermally induced regional air flow is known as the sea breeze. The strength of the sea breeze is dependent in part on the thermal contrast between land and sea, which increases until the sun ceases to heat the land.
In a flat coastal area such as Florida, the sea breeze brings air in more or less uniformly. But on the rugged Pacific Northwest Coast, the coastal mountains present a barrier to such a simple flow regime. Some air rises up the windward slopes forming clouds above the summits. But in gap areas such as the Strait of Juan de Fuca, the sea breeze can rush through the confluence zone, increasing in speed as the day progresses. The resulting gap winds not only are stronger than open water winds, they also raise surface waves and interact with tidal currents to pose additional hazards for those on the waters.
Similar gap wind effects are found around the world where shoreline topography interacts with the wind, often providing outlets for winds pushing out of the mountains during the winter. British Columbia's coastal arctic outflow winds and the gorge winds flowing down the Columbia River gorge are additional examples of these winds.
Copyright 2004, Keith C. Heidorn, All Rights Reserved. (Illustrations, unless otherwise specified, ©Keith C. Heidorn, All Rights Reserved. Base maps courtesy of NOAA)
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