How do clouds form

Do You Know Your Weather? Also, can you read Packed with interesting facts explained well. A fascinating and informative co A fascinating and informative course! Great course 27 Jun, Learn About Weather 25 Jun, Great cpurse 23 Jun, Clouds form when the invisible water vapour in the air condenses into visible water droplets or ice crystals.

There is water around us all the time in the form of tiny gas particles, also known as water vapour. There are also tiny particles floating around in the air — such as salt and dust — these are called aerosols. Aerosols make it easier for the water vapour to condense, and once the process starts, eventually bigger water droplets form around the aerosol particles, and these water droplets start to merge with other droplets, forming clouds.

Want to keep learning? This content is taken from University of Exeter online course. See other articles from this course. The process of water changing from a gas to a liquid is called "condensation," and when gas changes directly into a solid, it is called "deposition. Condensation happens with the help of tiny particles floating around in the air, such as dust, salt crystals from sea spray, bacteria or even ash from volcanoes.

Those particles provide surfaces on which water vapor can change into liquid droplets or ice crystals. Dust and other particles floating in the air provide surfaces for water vapor to turn into water drops or ice crystals.

The tiny drops of water condense on the particles to form cloud droplets. Clouds are made up of a bunch of cloud droplets bundled together with raindrops. We usually think of clouds as being up in the sky, but when conditions are right, a cloud can form at ground level, too. Although the basic idea of cloud formation is easy to understand, there is much more to learn. Sign up for our email newsletter. Already a subscriber?

Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Go Paperless with Digital. Paul A. Deck, assistant professor of chemistry at Virginia Polytechnic Institute and State University, gives a brief explanation: "The earth's atmosphere--especially local parts of the atmosphere--is not at thermal equilibrium.

Get smart. Sign Up. Support science journalism. Knowledge awaits. See Subscription Options Already a subscriber? Create Account See Subscription Options. Continue reading with a Scientific American subscription. Subscribe Now You may cancel at any time. Other times, the air has less water vapour and it feels drier and fresher. Clouds appear when there is too much water vapour for the air to hold.

The water vapour gas then condenses to form tiny water droplets liquid , and it is the water that makes the cloud visible. These droplets are so small that they stay suspended in the air. As a simple explanation, when air rises, it cools, much like when you are going up a mountain and the air tends to get colder. This means it turns from a gas to a liquid, much like when you get condensation on a cold window. When the water vapour turns to a liquid in the sky, it forms lots of tiny little water droplets which cling to little bits of dust; it is this group of little water droplets suspended in the air that becomes visible as the cloud we see.

These droplets of water are only about a hundredth of a millimetre in diameter, but the cloud is made up of a large collection of these. If the cloud is high up enough in the sky and the air is cold enough, the cloud is made of lots of tiny ice crystals instead and gives a thin, wispy appearance.