The natural world
How clouds form
Follow the quiet journey from invisible water vapor to the clouds moving overhead.
A short companion guide
A cloud can seem almost solid from below, yet it is made of tiny suspended droplets, ice crystals, or both. The story begins with water you cannot see: water vapor mixed into the air.
A change you can see
Water vapor is a gas. The visible part of a cloud is liquid water or ice. That distinction explains why a clear sky can contain moisture even when no clouds are present.
Rising air cools
As air rises into lower pressure, it expands and cools. If moist air cools enough to reach saturation, water can condense onto tiny airborne particles such as salt or dust. Many small droplets together become visible as a cloud.
Always taking shape
A cloud is constantly changing. Droplets form as water condenses and disappear as they evaporate. The next time you watch a cloud soften at its edges, you are seeing part of that ongoing exchange.
Explore a little further
Original companion notes on condensation and cloud formation, with further reading from NOAA. They are a brief introduction, not a transcript of the video.
