‘Levanter’ cloud seen over the Rock of Gibraltar

WEATHER NEWS: ‘Levanter’ cloud seen over the Rock of Gibraltar


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The unique landscape at the Rock of Gibraltar is the site of stunning flora and fauna that can’t be found elsewhere on the European continent — and it’s also the home of the rare Levanter cloud, which trails off the lone rock’s craggy peak.

Video from the Met Office Gibraltar shows a stunning levanter cloud — named after the Levant wind that blows westward across the local terrain — seemingly forming out of thin air.

In reality, the cloud’s formation isn’t miraculous — it is a byproduct of the Levant wind and the extreme landscape.

Moist surface air is forced upward by the sudden spike in topography and ascends to a height where the temperature is cooler than the surface air’s dew point. That means the air reaches saturation and the moisture within it condenses, forming a cloud.

In front of where the Levanter regularly forms is Gibraltar International Airport, where landing passenger jets and helicopters are treated to a rare and stunning view, even on cloudy days.

Some on the peninsula have started seeing the shapes of animals in the unusual cloud, which can only form when the Levant winds are blowing. According to the United Kingdom’s Royal Meteorological Society, the wind can blow through at any time of year but is most common from June through October.

The Levanter cloud is a special subset of a more common type of cloud — orographic clouds, meaning clouds that are formed by the Earth’s topography. Within the genre of orographic clouds are several types of clouds, namely banner clouds and lenticular clouds.

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The Levanter is best classified as a type of banner cloud, a cloud that forms off the top of isolated, sharp mountain peaks when winds are strong. The Rock of Gibraltar is a perfect place for these to form, but such clouds can also be sighted on peaks like Mount Everest in the Himalayas and the Matterhorn in the Alps.

Lenticular clouds are some of nature’s strangest. Shaped like a lens — or, a flying saucer — these rare clouds can be spotted near or on top of mountains themselves, in which case it is known as a “cap” cloud.

Lenticular clouds form when moist air is driven up a mountaintop and cools to the point of saturation, at which point it condenses into a cloud. Unlike banner clouds that stream across the sky, a lenticular cloud gets its unique shape when the moist air sinks after climbing the mountain and dries out, leaving a smaller, saucer-shaped cloud.

Orographic lift can also create unique climates on and around mountains. On the windward side of large mountains, where rising moist air condenses into dense clouds, a lot of rain and snow can fall, keeping the windward side lush and green. However, the remaining air that makes it over the mountain toward the leeward side is then without most of its moisture, leaving the leeward side of mountains high and extremely dry.

Dry climates tend to form on the lee side of mountains, which host famously dry locations such as California’s Death Valley and Chile’s Atacama Desert.

Matthew Cappucci contributed to this report.

correction

This story originally stated that the wind involved in the formation of the Levanter cloud blows in the eastward direction (or from the west); it actually blows in a westward direction (or from the east). The text has been updated.





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