Watch this video to learn more about wave clouds, or Kelvin-Helmholtz clouds.
Clouds that look like waves are rare and beautiful. These clouds – known as Kelvin-Helmholtz clouds, billow clouds, or shear-gravity clouds – might have been the inspiration for Van Gogh’s painting Starry Night. The next time you spot one of these remarkable wave clouds, capture a photograph and submit it to us!
Kelvin-Helmholtz clouds are named for Lord Kelvin and Hermann von Helmholtz, who studied the physics of the instability that leads to this type of cloud formation. A Kelvin-Helmholtz instability forms where there’s a velocity difference across the interface between two fluids: for example, wind blowing over water.
When might you get to see these beautiful clouds? Your odds are better on windy days, when there’s a difference in densities of the air – for example, during a temperature inversion – when warm air flows over cooler air. You’re also more likely to see these clouds near sunrise or sunset, another time when the bottom of the clouds are cooler and the air above is warmer. The clouds take on this wave shape when the air above is moving more quickly than the air below, pushing over the tops of the clouds and creating the rolling wave appearance. As you might have guessed, Kelvin-Helmholtz clouds are a sign that aircraft in the area will be experiencing turbulence.
View at EarthSky Community Photos. | EarthSky’s own Raúl Cortés captured these Kelvin-Helmholtz clouds from an airplane near Amsterdam on February 21, 2023. See the wave-shaped clouds above the gap? Thank you, Raúl!
Wave clouds from the EarthSky community
View at EarthSky Community Photos. | Grant Spratt in Surfers Paradise, Queensland, Australia, captured this view of wave clouds on November 29, 2023. Grant wrote: “View to south, chance of severe thunderstorm warning.” Thank you, Grant!View at EarthSky Community Photos. | Lori Mendez in Saint Helena, California, captured these Kelvin-Helmholtz clouds on November 13, 2023. Lori wrote: “Always beautiful sunsets from my work view. Leaving work tonight, everyone was taking pictures of these clouds. I have never seen clouds like this. I posted to Facebook and someone sent your link saying what they are called.” Thank you, Lori!View at EarthSky Community Photos. | Karen Gord in Mosheim, Tennessee, captured these wave clouds on November 15, 2023. Karen wrote: “A frosty, crisp 29-degree morning. The clouds caught my attention out the window. Beautiful. Never seen this before.” Thank you, Karen!View at EarthSky Community Photos. | Linda K. Tilley in Wyoming captured these Kelvin-Helmholtz clouds on November 11, 2023. Thank you, Linda!View at EarthSky Community Photos. | Kevin Horath took this image on October 12, 2023. Kevin wrote: “While sailing off the coast of Maine, I saw clouds that looked like waves.” Thank you, Kevin!
More photos of Kelvin-Helmholtz clouds
View at EarthSky Community Photos. | Early on the morning of May 23, 2021, Angus Weller spotted these Kelvin-Helmholtz clouds over the Coastal Mountain Range just north of Vancouver, British Columbia. Angus said: “It’s only the 2nd time I’ve seen this cloud formation.” Thank you, Angus!View at EarthSky Community Photos. | Michelle Berger in Sandpoint, Idaho, captured this photo of Kelvin-Helmholtz clouds on December 27, 2020. She wrote: “We were driving home one evening in December, 2 days after Christmas, and saw this beautiful image in the sky east of our way home.” Thank you, Michelle!View at EarthSky Community Photos. | Suzanne Kelley of Littleton, Colorado, caught these Kelvin-Helmholtz clouds – clouds that look like ocean waves – at sunset over the Rocky Mountains on New Year’s Eve, December 31, 2019. Thank you, Suzanne!View at EarthSky Community Photos. | Matty Hammersley in the UK wrote: “Taken by my wife Ems whilst I was driving south on M5, south of Birmingham/Black Country toward Worcestershire area.” The image is from around sunset, on March 28, 2022. The clouds are known as Kelvin-Helmholtz clouds. Thank you, Matty!
Kelvin-Helmholtz clouds from 2 sides of Earth
These photographers both captured Kelvin-Helmholtz clouds on the same day, from two sides of Earth.
View at EarthSky Community Photos. | Tim Hunter in Waitara, Taranaki, New Zealand, captured this photo of wave clouds on October 6, 2021. He wrote: “Was chatting to my father on the phone in my lounge, stood up from the couch, looked out the window and saw 2 waves and more forming. The formations lasted about a minute and a half before fading away. It was a beautiful sight. One I may never get to witness again.” Thank you, Tim!View at EarthSky Community Photos. | Julie Hinder in Slapton, Devon, UK, captured this photo of wave clouds on October 6, 2021. Thank you, Julie!
Wave clouds on other planets
Earth isn’t the only planet with Kelvin-Helmholtz clouds. Here they are on Saturn; Jupiter has them, too. Image via NASA/ Wikimedia Commons (public domain).
Bottom line: Clouds that look like waves across the sky are known as Kelvin-Helmholtz clouds. These clouds form from winds moving at two different speeds.
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