A cloud in a jar is a simple school project that shows how real clouds can form in the sky. Warm water in the jar makes water vapor, and ice on the lid cools the air above it. When the vapor cools and has tiny particles to stick to, it changes into tiny water droplets that look like a cloud.
This project helps students see part of the water cycle up close.
Key Facts
- Clouds form when water vapor cools and condenses into tiny liquid droplets or ice crystals.
- Evaporation: liquid water gains heat and becomes water vapor.
- Condensation: water vapor cools and becomes liquid water droplets.
- Warm air can hold more water vapor than cold air.
- Temperature change = final temperature - starting temperature.
- In this project, hot water provides vapor, ice cools the air, and smoke or spray gives droplets a place to form.
Vocabulary
- Evaporation
- Evaporation is the process in which liquid water changes into water vapor.
- Condensation
- Condensation is the process in which water vapor changes back into tiny liquid water droplets.
- Water vapor
- Water vapor is water in its gas form, which is invisible in the air.
- Cloud
- A cloud is a collection of tiny water droplets or ice crystals floating in the air.
- Water cycle
- The water cycle is the movement of water between Earth, the air, clouds, and back again as rain or snow.
Common Mistakes to Avoid
- Using cold water instead of hot water, which is wrong because less evaporation happens and there may not be enough water vapor to make a visible cloud.
- Skipping the ice on the lid, which is wrong because the warm vapor needs to cool before it can condense into tiny droplets.
- Thinking the cloud is smoke, which is wrong because the cloud is mostly tiny water droplets and the smoke or spray only helps the droplets start forming.
- Handling matches without an adult, which is wrong because matches can cause burns or fire and must be used only by a responsible adult.
Practice Questions
- 1 A jar starts with water at 25°C. Hot water raises the temperature to 65°C. What is the temperature change?
- 2 A student pours 200 mL of warm water into a jar and uses 50 mL during the experiment. How much water is left in the jar?
- 3 Explain why a cloud forms more easily when warm, moist air in the jar is cooled by ice on the lid.