Cumulus clouds – Weather – Science

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Cumulus clouds: puffy and white

These are cumulus clouds. They are puffy.

What is a cumulus cloud?

Cumulus clouds are clouds that are piled up on top of each other. “Cumulus” means a pile in Latin, as in our word “accumulate” meaning to pile up. They are puffy clouds.

(What are clouds made of?)

Sometimes cumulus clouds are white and there are only a few of them in the sky; other times they can be heavy and gray. They’re usually low-level clouds, only about 1000 meters (3300 feet) above the ground.

Cumulus clouds: gray and covering the whole sky

These are also cumulus clouds, even though they look a little different. They’re still puffy.

When do you see cumulus clouds?

Usually you get cumulus clouds when warm air rises from the ground carrying water vapor with it by evaporation. When the warm wet air rises up and meets some cold air, the water vapor gets colder and condenses into drops of water, making a cloud.

Which cumulus clouds are rain clouds?

When cumulus clouds are white and puffy, that usually means it’s not going to rain right away. But if they grow into big gray clouds, you can expect rain. Or it might snow if it is cold enough.

(Read more about rain)

White clouds are thin and let a lot of sunlight through them – that’s why they look white. Gray clouds are thicker, with more water. Less sunlight gets through them.

What’s a cumulo-nimbus cloud?

Cumulonimbus clouds: big and dark

Cumulonimbus clouds

A nimbus cloud is one that has rain or snow falling out of it. So a cumulo-nimbus cloud is one that is puffy and has rain or snow falling out of it.

(More about nimbus clouds)

What’s a strat0-cumulus cloud?

A stratus cloud is one that covers the whole sky like a blanket. So a strato-cumulus cloud is a combination of that blanket with a cumulus cloud. It’s a cloud that covers the whole sky, but is still puffy like clumps of cotton balls.

(More about stratus clouds)

Looking for a second source to cite? Check out this excellent article about cloud types from the National Oceanic and Atmospheric Administration.

Learn by doing: making a cloud
More about clouds

Bibliography and further reading about the atmosphere:


Learn by Doing – Clouds
More about clouds
More about Thunderstorms
And more about Weather home

By |2018-05-28T23:34:03+00:00August 20th, 2017|History|2 Comments
Cite this page: Carr, K.E. Cumulus clouds – Weather – Science. Study Guides, August 20, 2017. Web. November 16, 2018.

About the Author:

Dr. Karen Carr is Associate Professor Emerita, Department of History, Portland State University. She holds a doctorate in Classical Art and Archaeology from the University of Michigan. Follow her on Instagram, Pinterest, or Facebook, or buy her book, Vandals to Visigoths.


  1. Charlie Carroll October 16, 2018 at 11:32 am - Reply

    Cumulus clouds are very interesting.

    • Karen Carr October 17, 2018 at 8:44 pm

      Wonderful! I’m glad you liked hearing about them, Charlie.

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