Bizarre Holey Honeycomb-like Clouds Appear off South American Coast
A blanket of strange pock-marked clouds has been spotted by NASA satellites off the coast of Chile.
A picture of the beautiful cloud formations taken in August last year was featured as NASA Earth Observatory's Image of the Day for February 3, 2023.
It shows these holey clouds, known technically as organized marine stratocumulus clouds, hovering low over the Pacific Ocean, taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite.
Marine stratocumulus clouds form over oceans, usually at lower altitudes of below a mile above the surface. Organized marine stratocumulus clouds, as seen in the picture, form only in the subtropics and mid-latitudes, and come in two forms: open-cell and closed-cell.
While closed-cell clouds look as if a honeycomb has been filled with clouds, open-cell clouds look like an empty honeycomb structure, with the edges of the cells visible and no cloud within.
These strange clouds are actually rather common: On average, 23 percent of the global oceans are covered with marine stratocumulus clouds, equating to around 15 percent of Earth's total surface, NASA Earth Observatory reported.
However, scientists weren't aware of this until the first weather satellites were launched, as the cells were too large to be properly detected from the ground. The open-cell clouds were first photographed in February 1961.
Organized marine stratocumulus clouds form in the shape of Rayleigh-Bénard cells, which are hexagonal cells formed naturally when fluids are heated from below. As warm air over the ocean rises and expands, it then cools and condenses into clouds.
In open-cell clouds, the warm air rises along the edges of the cells and the cool air sinks through the middle, while in closed-cell clouds, the opposite occurs, with the warm air rising in the center and cool air sinking at the edges. Each cell is around a maximum of 45 miles across.
"A similar phenomenon to these cloud cells is water boiling, in which the temperature drop from the pot's heated base to the upper surface causes the water to rise and fall in columns," Ilan Koren of the Weizmann Institute's Environmental Sciences and Energy Research Department said in 2011. "This rolling, cell-like pattern, known as Rayleigh-Bénard convection, was described over a hundred years ago."
The western edges of continents are more prone to these types of clouds. Firstly the atmosphere is more stable closer to land masses like continents, and second, ocean temperatures are lower relative to other areas at the same latitude.
The beautiful honeycomb-like clouds don't last very long: open-cell clouds generate more rainfall than closed-cell clouds, causing them to break up in shape much faster than closed-cell clouds, which can keep their structure for up to 10 hours. Additionally, atmospheric pollution like smoke, dust and ship exhaust aerosols can cause one type of cloud cell to transition into the other.
The picture of these bizarre clouds over the Pacific in 2022 shows a larger system of cells than are usually seen. This could possibly be due to atmospheric instabilities, rain, or other atmospheric variations.
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