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Marine Stratocumulus Clouds

Marine stratocumulus clouds (MSCs) typically lie at low-altitudes below 6,000 feet, covering about 20 percent of the low-latitude oceans, or 6.5 percent of the Earth’s surface.

MSCs usually form over water and have either closed- or open-cell forms—⁠the difference has to do with their cloud cover. Closed-cell MSCs cover nearly 100 percent of the underlying Earth’s surface and reflect a large portion of solar radiation. Open-cell MSCs, on the other hand, have broken cloud structures that surround areas of clear sky, which do not block much solar radiation.

Image of clouds

The image above contains both forms of these clouds. Can you tell which ones are which? 

Interestingly, changes in the local air quality have been found to affect these clouds. In fact, a study published in the Journal of Geophysical Research found that emissions, such as those from ships, can cause the transition from open- to closed-cell MSCs over large areas. Additionally, another study from JGR Atmospheres found that dust, smoke, pollutants, and other aerosols from continents can cause the same effect.

See additional examples below.

Image of clouds
On Jan. 5, 2021, the GOES East satellite, using Band 2 of the ABI instrument , viewed percolating clouds approximately 3,000 miles off of the coast of Chile, north of Easter Island and the Pitcairn Islands. Band 2, which has the finest resolution of all of the 16 bands on the ABI, is called “red” because it picks up specific wavelengths that read out as that color on processed imagery. Due to its detail, it is also the band that is best suited to viewing clouds and the changes they undergo.
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Image of clouds
The NOAA-20 satellite snapped this beautiful photo of marine stratocumulus clouds (MSCs) off the western coast of South America on Dec. 3, 2019. These typically lie at low-altitudes below 6,000 feet, covering about 20 percent of the low-latitude oceans, or 6.5 percent of the Earth’s surface.
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