Shop Windows to the Universe

Young Voices for the Planet DVD in our online store includes 8 films where students speak out and take action on climate change.
This is a photograph of altocumulus clouds.
Click on image for full size
Courtesy of UCAR Digital Image Library

Altocumulus

Altocumulus clouds (weather symbol - Ac), are made primarily of liquid water and have a thickness of 1 km. They are part of the Middle Cloud group (2000-7000m up). They are grayish-white with one part of the cloud darker than the other. Altocumulus clouds usually form in groups.

You can distinguish an altocumulus cloud from a stratocumulus cloud by pointing your hand toward the cloud. If the cloud is about the size of your thumbnail, then it is altocumulus.

Altocumulus clouds in view on a warm humid morning indicate thunderstorms by late afternoon.


Last modified September 25, 2007 by Becca Hatheway.

Shop Windows to the Universe Science Store!

The Fall 2009 issue of The Earth Scientist, which includes articles on student research into building design for earthquakes and a classroom lab on the composition of the Earth’s ancient atmosphere, is available in our online store.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

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

Middle Clouds

The middle cloud group consists of Altostratus and Altocumulus clouds. The prefix alto- means 'middle.' Middle clouds consist of ice crystals and water droplets. The base of a middle cloud above the surface...more

Stratocumulus

Stratocumulus (weather symbol - Sc) clouds consist of water droplets and belong to the Low Cloud (surface-2000m) group. These clouds are low, lumpy, and gray. These clouds can look like cells under a microscope...more

Thunderstorms

Thunderstorms are one of the most thrilling and dangerous types of weather phenomena. Over 40,000 thunderstorms occur throughout the world each day. Thunderstorms form when very warm, moist air rises into...more

Altostratus

Altostratus clouds (weather symbol - As) consist of water and some ice crystals. They belong to the Middle Cloud group (2000-7000m up). An altostratus cloud usually covers the whole sky and has a gray...more

Mysterious Clouds Produced When Aircraft Inadvertently Cause Rain or Snow

As turboprop and jet aircraft climb or descend under certain atmospheric conditions, they can inadvertently "seed" mid-level clouds, causing narrow bands of snow or rain to develop and fall to...more

Cloud Formation Due to Weather Fronts

Weather fronts can cause clouds to form. Fronts occur when two large masses of air collide at the Earth's surface. Warm fronts produce clouds when warm air replaces cold air by sliding above it. Many different...more

Altocumulus

Altocumulus clouds (weather symbol - Ac), are made primarily of liquid water and have a thickness of 1 km. They are part of the Middle Cloud group (2000-7000m up). They are grayish-white with one part...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