This is a photo of mammatus clouds, taken in Weld County, Colorado.
Click on image for full size
Photo courtesy of Gregory Thompson

Mammatus

Mammatus clouds are pouches of clouds that hang underneath the base of a cloud. Usually mammatus clouds form with cumulonimbus clouds.

Mammatus clouds can look like a field of tennis balls or melons.

Last modified November 30, 2007 by Becca Hatheway.

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Cumulonimbus

Cumulonimbus clouds belong to the Clouds with Vertical Growth group. They are also known as thunderstorm clouds. A cumulonimbus cloud can grow up to 10km high. At this height, high winds make the top...more

Cloud Formation and Weather Fronts

Weather fronts can cause clouds to form. Fronts happen when two large masses of air collide into each other at the Earth's surface. Warm fronts produce clouds when warm air replaces cold air by sliding...more

Altocumulus

Altocumulus clouds are part of the Middle Cloud group. They are grayish-white with one part of the cloud darker than the other. Altocumulus clouds usually form in groups. Altocumulus clouds are about...more

Altostratus

Altostratus clouds belong to the Middle Cloud group. An altostratus cloud usually covers the whole sky. The cloud looks gray or blue-gray. The sun or moon may shine through an altostratus cloud, but will...more

Cirrocumulus

Cirrocumulus clouds belong to the High Cloud group. They are small rounded puffs that usually appear in long rows. Cirrocumulus are usually white, but sometimes appear gray. Cirrocumulus clouds are the...more

Cirrostratus

Cirrostratus clouds belong to the High Cloud group. They are sheetlike thin clouds that usually cover the entire sky. The sun or moon can shine through cirrostratus clouds. When looking at the sun through...more

Cirrus

Cirrus clouds are the most common of the High Cloud group. They are made of ice crystals and have long, thin, wispy streamers. Cirrus clouds are usually white and predict fair weather. ...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA