Weather & Cloud Formation Simulator
Lift an air parcel up a mountain and see it cool, reach the dew point and form clouds and rain.
Wind carries moist sea air up a mountain. It cools as it rises, its water vapour condenses into cloud and it rains on the windward side. The dry air that sinks down the other side warms up and creates a rain shadow. Change sea temperature, humidity, wind and mountain height, or drag the marker to sample the air anywhere along its path.
About the Weather & Cloud Formation Simulator
Free weather & cloud formation simulator. Lift an air parcel up a mountain and see it cool, reach the dew point and form clouds and rain. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for earth & space, the weather & cloud formation simulator runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Lift an air parcel up a mountain and see it cool, reach the dew point and form clouds and rain. Use it to explore earth & space ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Weather & Cloud Formation Simulator
- Use the controls to change Sea surface temperature, Humidity (relative), Mountain height, Wind speed, Look at. The simulation reacts instantly.
- Pick an option such as Auto (all air), Drag the marker, Clouds + rain, Temperature colours to switch modes or load an example.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Lift the parcel up to the cloud base.
- Raise the dew point and watch the cloud base drop.
- Lift it very high to make rain.
Key ideas you can learn
- Rising air expands and cools.
- When the air cools to its dew point, vapour condenses into cloud.
- Air pressure falls with height.
- Deep clouds in moist air produce rain.
Where this is used in the real world
Weather forecasters, pilots and mountain climbers use these ideas to predict clouds, fog and storms.
Who is this simulation for?
Astronomy and earth-science students, and teachers who need a visual model to explain what is happening in the sky.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
What is the dew point?
The temperature at which air becomes saturated and water vapour condenses.
Why does air cool as it rises?
It moves into lower pressure, expands, and does work, so its temperature drops (about 9.8 °C per km when dry).
Is the Weather & Cloud Formation Simulator free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Weather & Cloud Formation Simulator work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.