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May 28, 2026 - Open and Closed Cell Clouds off of Peru
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Dark patches punctuated widespread white clouds off the coast of Peru in this true-color satellite image acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite on May 25, 2026.
The bright deck of stratocumulus clouds are called closed-cell clouds while the darks patches mark areas of closed-cell clouds. The major difference between open-cell and closed-cell clouds relates to the flow of air in the cells. In closed-cell clouds, moist, warm air rises in the center and sinks around the edges. In contrast, open-cell clouds have air sinking in the center of the cells and rising along the edges.
In two locations, the open-cell clouds take on a star-shaped form. These unusual clouds are known as “actinoform”, a word derived from the Greek word meaning “ray”. Scientists have described actinoform clouds since the early 1960s, but only recently have begun to understand where and why they form. It is known that they generally form in the lower part of the atmosphere, at roughly 6,600 feet above Earth. They also form over water and in or near large banks of stratocumulus clouds, especially over the Pacific Ocean. They seem to be particularly common off the coast of Peru, where a review of satellite images by one researcher showed actinoform clouds present in about 25 percent of images.
Image Facts
Satellite:
Terra
Date Acquired: 5/25/2026
Resolutions:
1km (565.6 KB), 500m (1.6 MB), 250m (2.4 MB)
Bands Used: 1,4,3
Image Credit:
MODIS Land Rapid Response Team, NASA GSFC
Dark patches punctuated widespread white clouds off the coast of Peru in this true-color satellite image acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite on May 25, 2026.
The bright deck of stratocumulus clouds are called closed-cell clouds while the darks patches mark areas of closed-cell clouds. The major difference between open-cell and closed-cell clouds relates to the flow of air in the cells. In closed-cell clouds, moist, warm air rises in the center and sinks around the edges. In contrast, open-cell clouds have air sinking in the center of the cells and rising along the edges.
In two locations, the open-cell clouds take on a star-shaped form. These unusual clouds are known as “actinoform”, a word derived from the Greek word meaning “ray”. Scientists have described actinoform clouds since the early 1960s, but only recently have begun to understand where and why they form. It is known that they generally form in the lower part of the atmosphere, at roughly 6,600 feet above Earth. They also form over water and in or near large banks of stratocumulus clouds, especially over the Pacific Ocean. They seem to be particularly common off the coast of Peru, where a review of satellite images by one researcher showed actinoform clouds present in about 25 percent of images.
Image Facts
Satellite:
Terra
Date Acquired: 5/25/2026
Resolutions:
1km (565.6 KB), 500m (1.6 MB), 250m (2.4 MB)
Bands Used: 1,4,3
Image Credit:
MODIS Land Rapid Response Team, NASA GSFC
