Levant (wind)

The wind rises in the central Mediterranean or around the Balearic Islands and blows westwards reaching its greatest intensity through 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, current or swell through the Strait, which is a narrow sea-level passage about 15 km (9.3 mi) wide and 55 km (34 mi) long that is surrounded by terrain reaching several thousand feet.

Such an inversion provides a cap that contains the low-level air and results in greater topographic blocking and the acceleration of the airflow through the gap forming the Strait.

Levanters are most frequent during the warm season from April until October and often reach a peak in spring, when the Mediterranean is comparatively cool, increasing the stability of the low-level air flow.

At high wind speeds, the turbulent mixing to the lee of the Rock distributes the moisture through a comparatively deep layer and the cloud is, at best, very broken.

The pennant cloud is not seen in westerly winds, although many of the same processes occur - it is just that the air is usually drier and may be warmer, as well as being less stable – so that convection from the surface is deeper and not capped near the mountaintop level.

Around dawn, the flow is relatively smooth through the cloud, but later in the morning, as it becomes warmer, some convective overturning develops within the plume as temperatures rise.

Formation of the cloud is classically very near the top of the ridge-line of the Rock at nearly 400 m (1,300 ft) altitude, but the base is usually a little lower in the turbulent flow to the west.

Usually, this produces light and rather variable winds near sea level, at times forming a cyclonic circulation area over Gibraltar Bay and the town.