Levant (wind) - The Strait of Gibraltar

The Strait of Gibraltar

The Strait of Gibraltar, located at the western entrance to the Mediterranean Sea, is frequently associated with strong gap winds that can produce dangerous seas, especially when they blow against tide and current. The Strait of Gibraltar represents a narrow sea-level passage about 15 km wide and 55 km long that is surrounded by terrain reaching several thousand feet.

The most pronounced gap wind though the Strait is from the east and is known as the Levanter, which can produce winds of 20-40 kt in and to the west of the gap. High pressure is found over the eastern Mediterranean, with lower pressure to the west of Gibraltar. The sinking motions accompanying such anticyclonic conditions often results in the formation of an inversion a few thousand feet above the surface. Such an inversion provides a vertical stable layer or cap that contains the low-level air and results in greater topographic not blocking and weaker gap flow. A large horizontal gradient exists over the Strait, and winds accelerate downgradient from high to low pressure within the gap. Under such circumstances, the winds can go from near calm in the western Mediterranean (known as the Alboran Sea) to gale force strength on the western side of the Strait. The strongest winds are not observed mid-Strait, as might be expected if the funnel mechanism was dominant; rather, the strongest winds are over the western Strait and immediately downwind to the west. Levanters are most frequent during the warm season from May through October.