Fish-Shaped Clouds Swim Over Patagonia's Glacial Lake

When an astronaut looked down at Patagonia from the International Space Station on December 27, 2025, they spotted something magical: a school of fish-shaped clouds swimming above Argentina's brilliant blue Lago Argentino.

The remarkable image shows what NASA scientists believe are lenticular clouds, a rare formation that happens when strong winds sweep up and over mountains. As air rushes over the Andes, it creates invisible waves in the sky, causing moisture to condense at the wave crests and evaporate in the troughs.

"The lens shape reminds me of lenticular clouds, which usually form near or over mountains," said Maria Hakuba, a research scientist at NASA's Jet Propulsion Laboratory. The smooth edges suggest these clouds formed at high altitude, around 30,000 feet up, where temperatures drop low enough to create ice crystals.

The fish-like shapes came from wind shear and turbulence stretching the clouds horizontally above the lake. Shadows cast onto the landscape below made their forms even more striking, creating the illusion of fish gliding through the sky.

Patagonia turns out to be a hotspot for these eye-catching clouds. Strong surface winds common in the region sweep across the glacial lakes of Los Glaciares National Park, forcing unusually moist air over the Andes. Even the sublimation of glacial ice, when ice converts directly to water vapor, adds extra moisture that helps these clouds form.

"Very often the clouds here are stationary and trapped by lee waves on the downwind side of the mountains," explained Santiago Gassó, an atmospheric scientist at NASA's Goddard Space Flight Center. They hover in place like sky sculptures, sometimes described as looking like flying saucers, stacks of pancakes, or in this case, swimming fish.

Why This Inspires

This photograph reminds us that Earth is constantly creating unexpected beauty. From 250 miles above our planet, astronauts witness daily miracles that most of us never see: the dance between wind and water, ice and air, creating fleeting art galleries in the sky.

The image also shows how citizen science is making these discoveries accessible to everyone. Through NASA's GLOBE Clouds project, students and the public can contribute to cloud research and learn to identify formations using interactive tools. Anyone can become a cloud detective.

These fish clouds tell a remarkable story of how our planet's systems interact, from glacial lakes to towering mountains to atmospheric circulation, all working together to paint the sky.