Choose starting water
Changing the parcel water resets it to the warm starting temperature.
Cloud Maker
Cool a closed moist air parcel and watch invisible vapor condense into liquid cloud droplets.
Grades 3–5 · Earth Science
Your goal
Begin with 8 water units in the air parcel. Cool it until 2 units have condensed into liquid cloud droplets.
Reduced motion is on. The controls still update the scene.
30 degrees. Saturation amount 14 units. 12 units are vapor and 0 units are liquid droplets. All water is invisible vapor.
Water stays inside one closed air parcel. A simple linear saturation table is used only to show the direction of change, not real humidity values. Cooling causes excess vapor to condense around assumed particles; warming evaporates droplets. Water vapor is invisible. A visible cloud consists of tiny liquid droplets here. The model omits rising-air expansion, precipitation, ice crystals and latent heat.
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Learn with Cloud Maker
Cloud Maker lets elementary students follow water as a moist air parcel cools. Choose the starting water amount, then lower the temperature in five-degree steps. When the simplified saturation amount falls below the parcel water total, some vapor becomes liquid droplets and a cloud appears. Warming reverses the change without changing the total water. Students aim for different droplet amounts and compare vapor with liquid. The symbols distinguish invisible vapor from the tiny liquid droplets that make a cloud visible in this model.
What to look for
Cool toward saturation
Droplets appear when total water exceeds the modeled saturation amount.
Reverse the change
Warm the same parcel to evaporate droplets. Vapor and liquid still add to the same total.
For teachers and curious learners
Distinguish invisible water vapor from visible liquid droplets while conserving parcel water during cooling and warming. Ask students to predict what will happen, change one setting, and explain what they observe. Learn gives a starting point. Practice and Challenge offer new goals with the same scene.
A closed parcel uses a linear illustrative saturation table and assumed condensation particles. Values are not real humidity data. Rising-air expansion, precipitation, ice and latent heat are omitted.