Fish-shaped clouds photographed over Lago Argentino likely lenticular, NASA scientists say

An astronaut aboard the International Space Station photographed a group of fish-shaped clouds hovering over Lago Argentino in Patagonia on December 27, 2025. Determining the clouds' type and origin from the photograph alone is challenging, but several NASA scientists and university researchers offered a theory after reviewing the image.

Maria Hakuba, a research scientist in the aerosols and clouds group at NASA's Jet Propulsion Laboratory, said "The lens shape reminds me of lenticular clouds, which usually form near or over mountains," and that "The edges of the cloud also look quite smooth rather than 'fuzzy,' which suggests they're ice clouds that are relatively high up." Hazem Mahmoud, an atmospheric science lead at NASA's Langley Research Center, cited MODIS data that suggest cloud-top altitudes near 9,200 meters (30,000 feet), cloud-top temperatures around 220 Kelvin, and relatively large particle sizes consistent with ice crystals.

"The high altitude and microphysical properties suggest Cirrocumulus lenticularis," he said, adding that strong surface-level winds in Patagonia, sublimation of glacial ice, wind shear and turbulence likely helped form and elongate the lens-shaped clouds while shadows accentuated their fish-like appearance.

Key Topics

Science, Lago Argentino, Patagonia, Andes, Lenticular Clouds, Modis