☁️ Cloud in a Jar
Use hot water, ice, and hairspray to create a real cloud inside a glass jar — and learn how clouds form in the sky!
🧰 What you need
Safety note: Ask an adult to handle the hot water. Use minimal hairspray and ensure the room is ventilated.
🔬 Steps
- 1
Ask an adult to pour 3 cm of very hot (near-boiling) water into the jar. Swirl it around to warm the jar sides.
- 2
Quickly spray a very brief burst (1 second) of hairspray into the jar.
💡 Just a tiny amount of hairspray — it provides aerosol particles that help water vapour condense. - 3
Immediately place the plate of ice cubes on top of the jar to seal it.
- 4
Watch closely over 30–60 seconds — a misty cloud will form in the middle of the jar!
💡 Use a dark background behind the jar — a black piece of card — to see the cloud more clearly. - 5
Remove the ice plate and watch the cloud dissipate (disappear) as the temperature equalises.
🧠 The Science
Hot water at the bottom of the jar evaporates, creating warm moist air that rises. When this warm moist air rises and meets the cold layer coming down from the ice, it cools rapidly. Cold air cannot hold as much water vapour as warm air. But water vapour needs something to condense onto — tiny particles in the air (in nature: dust, pollen, sea salt; in our jar: hairspray droplets). Water vapour condenses around these particles and forms tiny water droplets — a cloud! Real clouds form exactly this way: warm moist air rises, cools, and condenses around tiny atmospheric particles.
📚 Related Lessons
- 💨 Air We Breathe — Air is all around us — we breathe in oxygen and breathe out carbon dioxide, and plants keep our air fresh!
- ☁️ Clouds and Rain — Clouds form when water vapour rises and cools — and when they get heavy, they release rain that grows our food!
- 🔄 Water Cycle — Water evaporates from oceans, rises as vapour, forms clouds through condensation, and falls as rain — endlessly!