Quick Facts
Where? The west coast of the Iberian Peninsula (Spain and Portugal).
What’s in the photo? A cloud front swirling along the coastline.
What was this photo taken of? NASA’s Terra satellite.
When was this filmed? July 16, 2017.
This striking photo shows a rare vortex cloud that formed perfectly along the west coast of the Iberian Peninsula in 2017.
This vortex is created by the swirling of moist, cloudy air from the ocean and clear, dry air from the land, caused by a phenomenon called cyclonic rotation, which is the same mechanism that causes tropical cyclones. Hurricanes, typhoons, cyclonesaccording to NASA’s Earth Observation Satellite.
But in this case, the rotation was much slower and weaker than it would be in a tropical storm, so the cloudy and dry air didn’t mix completely and a proper vortex didn’t form. This also prevented the clouds from passing over land. (The image has been edited slightly to include more infrared light to highlight the difference between land and clouds.)
“What is the cause? [unusual] The mid-latitude rotation remains a mystery.” Stephen Joseph Munchak“This could have been caused by a gyre, a temporary, swirling current of water that extends deep below the ocean’s surface,” a meteorologist at NASA’s Laboratory for Mesoscale Atmospheric Processes told NASA’s Earth Observatory. But it could also have been caused by a gyre, a temporary, swirling current of water that extends deep below the ocean’s surface, he added.
Due to the heatwave It swept across Southern Europe in July 2017. There was also a larger-than-normal temperature difference between the cloudy ocean air and the dry land air, which may have further prevented the two fronts from mixing together, creating the striking spiral shape. According to NASA’s Earth Observatory, temperatures in Spain and Portugal were over 104 degrees Fahrenheit (40 degrees Celsius) when this photo was taken.
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The swirling clouds are marine stratocumulus clouds, which are low-lying clouds that usually exist below an altitude of 6,000 feet (1,830 meters) and can cover up to 6.5 percent of the Earth’s surface at any one time, according to the National Oceanic and Atmospheric Administration. National Oceanic and Atmospheric Administration (NOAA).
Interestingly, marine stratocumulus clouds typically only appear along the west coast of Earth’s land masses, according to NOAA. This is because they form when cold deep ocean water is brought to the surface by the Earth’s rotation, cooling the air above and causing water vapor to condense into clouds (also known as the Coriolis effect). Along the east coast, the Coriolis effect doesn’t push cold water toward the coast, meaning it doesn’t rise toward the surface.
The rotating cloud seen in the images stretched for hundreds of miles and likely lasted for several days, but NASA’s Earth Observatory says it’s unlikely to have produced rain.
NASA’s Earth-observing satellites have seen similar cloud depressions off the coast of the Iberian Peninsula and the west coast of Morocco in the past, but they don’t usually form as clearly defined as the vortex seen in this photo.
