Clouds Swimming over Lago Argentino

When an astronaut aboard the International Space Station snapped this photograph of Lago Argentino in Patagonia on December 27, 2025, a college of fish-shaped clouds lingered over the glacial lake’s teal waters. Determining the clouds’ sort and origin from the {photograph} alone is difficult, however a number of NASA scientists and college researchers supplied a concept after reviewing the picture.

“The lens form jogs my memory of lenticular clouds, which normally kind close to or over mountains,” stated Maria Hakuba, a analysis scientist within the aerosols and clouds group at NASA’s Jet Propulsion Laboratory. “The edges of the cloud also look quite smooth rather than ‘fuzzy,’ which suggests they’re ice clouds that are relatively high up.”

Lenticular clouds kind because of lee waves, which develop when prevailing winds are pressured up and over a topographic barrier, typically a mountain range, and when the overlying air is secure. Air expands and cools on the crest of the waves, inflicting vapor to condense and kind cloud droplets. Conversely, air on the opposite facet of the waves descends, warming the air and inflicting the cloud to evaporate. The result’s a set of seemingly stationary clouds that hover in place downwind of mountains. Lenticular clouds are sometimes eye-catching, typically described as having shapes like almonds, upside-down dinner plates, lentils, alien craft, or stacks of pancakes.

Hazem Mahmoud, an atmospheric science lead at NASA’s Langley Research Center, agreed that the clouds have been seemingly lenticular and supplied extra perception. MODIS (Moderate Resolution Spectroradiometer) information recommend cloud-top altitudes close to 9,200 meters (30,000 toes) and cloud-top temperatures round 220 Kelvin, together with comparatively massive particle sizes in line with the presence of ice crystals, he stated. “The excessive altitude and microphysical properties recommend Cirrocumulus lenticularis,” he stated.  

Strong surface-level winds frequent in Patagonia seemingly swept throughout the glacial lakes of Los Glaciares National Park, forcing unusually moist air over the Andes, producing the lens-shaped clouds. Sublimation—the conversion of ice immediately into water vapor—of glacial ice seemingly contributed to their formation by including additional moisture into the air, he added.

Wind shear and turbulence might have induced the elongated, trailing look that made the clouds resemble a college of fish, Mahmoud defined. These forces stretched and arranged the clouds horizontally above the lake, whereas shadows solid onto the panorama accentuated their kinds. “Together these clouds tell a remarkable story of interaction between the lake’s moisture source, the Andes’ dynamic topography, and atmospheric circulation,” he stated.

Santiago Gassó, an atmospheric scientist at NASA’s Goddard Space Flight Center, agreed they have been seemingly lenticular clouds, citing the environmental context and Patagonia’s repute as a hotspot for lenticular cloud formation.

“Very often the clouds here are stationary and trapped by lee waves on the downwind side of the mountains,” Gassó stated. “They often don’t precipitate because most of the moisture gets left on the west side of the mountain.” The stereotypical picture of lenticular clouds is that they sit stationary on the high of mountains, however in actuality, they have a tendency to float away “depending on the turbulence and flow,” he added.       

All three scientists agreed that with out analyzing extra information, it is onerous to say definitively whether or not the cloud is lenticular or a sort of cumulus. The problem with a single astronaut {photograph} or satellite tv for pc picture is that we largely see the cloud-top properties, Mahmoud stated. “If we also had lidar or cloud radar data, we could measure the vertical structure and thickness and more confidently differentiate a thin lenticular layer from a deep cumulonimbus column,” he stated.  

Whether cumulus or lenticular, it’s a coincidence that “fish” is the title atmospheric scientists typically use to explain formations of a sort of shallow convective cloud discovered over the ocean. It was one of many patterns, together with “sugar,” “gravel,” and “flowers,” recognized by a crew of researchers who analyzed decades of MODIS cloud observations.

Readers with a penchant for cloud classification can take part in GLOBE Clouds, a GLOBE citizen science mission that makes it attainable for college students and members of the general public to contribute to NASA analysis initiatives. As a part of the mission, contributors have the chance to make use of Clouds Wizard, a function that guides customers via cloud identification with a sequence of interactive questions, animations, and images.

Astronaut {photograph} ISS074-E-8940 was acquired on December 27, 2025, with a Nikon Z9 digital digital camera utilizing a focal size of 116 millimeters. It is offered by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit at NASA Johnson Space Center. The picture was taken by a member of the Expedition 74 crew. The picture has been cropped and enhanced to enhance distinction, and lens artifacts have been eliminated. The International Space Station Program helps the laboratory as a part of the ISS National Lab to assist astronauts take photos of Earth that can be of the best worth to scientists and the general public, and to make these photos freely out there on the Internet. Additional photos taken by astronauts and cosmonauts may be seen on the NASA/JSC Gateway to Astronaut Photography of Earth. Story by Adam Voiland.

• Alexander, J.M. & Teitelbaum, H. (2011) Three-dimensional properties of Andes mountain waves observed by satellite: A case study. Journal of Geophysical Research Atmospheres, 116(D23).
• American Meteorological Society Lenticularis. Accessed January 14, 2026.
• American Meteorological Society Cumulus. Accessed January 14, 2026.
• Bony, S., et al. (2020) Sugar, Gravel, Fish, and Flowers: Dependence of Mesoscale Patterns of Trade-Wind Clouds on Environmental Conditions. Geophysical Research Letters, 47(7), e2019GL085988.
• DLR Institute of Atmospheric Physics (2020, September 7) Discovery of record-breaking mountain waves above the South American Andes. Accessed January 14, 2026.
• The GLOBE Observer What is GLOBE Clouds? Accessed January 14, 2026.
• Mount Washington Observatory A Closer Look at Lenticular Clouds. Accessed January 14, 2026.
• NASA Earth Observatory (2024, September 12) Marvelous Lenticularis. Accessed January 14, 2026.
• Pautet, P.D., et al. (2021) Mesospheric Mountain Wave Activity in the Lee of the Southern Andes. Journal of Geophysical Research: Atmospheres 126(7).
• Smith, R. (2005) Orographic Atmospheric Phenomena in Patagonia: A preliminary survey. Croatian Meteorological Journal, 40(40), 325-328.
• World Meteorological Organization Lenticularis. Accessed January 14, 2026.