Andrew Ashton in Nampa, Idaho submitted this beautiful shot, which I believe he captured earlier this week. The pouch-like protrusions hanging from the undersides of these clouds are called mammatus clouds.
One interesting aspect of mammatus clouds is that they’re formed by sinking air. Most clouds are formed by rising air. They typically indicate stormy weather, but, contrary to myth, they don’t continue extending downward to form tornados.
Deborah Byrd created the EarthSky radio series in 1991 and EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. 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.