English: On July 29,2022, the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a true-color image of lacy patterns in the clouds off the west coast of Peru.

Marine stratocumulus clouds frequently form over the Pacific Ocean near the coast of Peru and Chile, especially during austral winter (June through August). The lacy patterns are created by closed-cell clouds, while and open-celled clouds help form a more solid-appearing, puffy, blanket of cloud. The main difference between the two cloud types relates to the flow of air. Moist, warm air rises in the center of closed cells and sinks around the edges. Open-cell clouds have air sinking in the center of cells and rising along the edges. In both cases, clouds form when parcels of warm air rise, expand, and cool enough for water vapor to condense into liquid droplets.

Another difference between these two types of marine stratocumulus clouds is precipitation. Uninterrupted decks of closed-cell clouds generally produce little to no rain, whereas open cells tend to occur as light rain begins to fall.