Mammatus clouds are pouch-like protrusions hanging from the undersides of clouds. You’ll usually find them under thunderstorm anvil clouds. But you might see them under other types of clouds as well. They’re composed primarily of ice, and groups of them can extend hundreds of miles in any direction. But they’re fleeting, remaining visible in your local sky for perhaps 10 or 15 minutes at a time.
People associate these cloud pouches with severe weather. And it’s true; they typically appear around, before or after a storm.
In fact, most clouds are formed by rising air. But mammatus clouds are interesting in part because they’re formed by sinking air.
They appear ominous. And they do signify storms. But, in a way that’s so common in nature, their dangerous aspect goes hand-in-hand with a magnificent beauty.
Beautiful bubbling clouds
View at EarthSky Community Photos. | Aaron Watson captured this image on June 17 2025, from Colorado and wrote: “Interesting mammatus clouds this morning. It looked like long deep grooves across the sky.” Thank you, Aaron!View at EarthSky Community Photos. | Lina Tomlin in Texarkana, Texas, caught these mammatus clouds on April 29, 2024. Lina wrote: “Stepped outside and my jaw dropped. I loved watching this massive storm cell roll by. I saw more ‘bubble’ clouds appear, and as the sun went down they lit up. I’ve never been this close to clouds like that. Thrilling!” Thank you, Lina!
Beautiful, bubbling clouds from 2023
View at EarthSky Community Photos. | Filipp Romanov in Yuzhno-Morskoy, Russia, captured these mammatus clouds on June 4, 2023. Thank you, Filipp!EarthSky’s Kelly Kizer Whitt shared this photo of mammatus clouds from Colter Bay in Grand Teton National Park on May 30, 2023.
Mammatus clouds from 2022
View at EarthSky Community Photos. | Peg Yates in Woodbridge, Virginia, took this image on August 22, 2022. Peg wrote: “Mammatus clouds in the western sky when the sun was setting.” Thank you, Peg!View at EarthSky Community Photos. | Michael Geib caught these mammatus clouds from Akron, Ohio, on July 20, 2022. Thank you, Michael!Mammatus clouds from Kelly Kizer Whitt at the Amtrak station in Whitefish, Montana, on July 7, 2022. See the mammatus clouds on the far underside of the storm? Image via Kelly Kizer Whitt.
Bottom line: Mammatus clouds look like bubbling, low-hanging clouds. They’re often associated with thunderstorms. Learn more about them here and see photos.
Our Editor-in-Chief Deborah Byrd works to keep all the astronomy balls in the air between EarthSky's website, YouTube page and social media platforms. She's the primary editor of our popular daily newsletter and a frequent host of EarthSky livestreams. Deborah created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Prior to that, she had worked for the University of Texas McDonald Observatory since 1976, and created and produced their Star Date radio series. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. In 2020, she won the Education Prize from the American Astronomical Society, the largest organization of professional astronomers in North America. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.
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