- Glass jar
- Plastic cup
- Push pin
- Cotton balls
- Food coloring (optional)
This activity focuses on one of the most important parts of the water cycle – precipitation.
Clouds form from water or ice that has evaporated from Earth’s surface. (You can find more information on the water cycle in this Weather For Kids.)
Evaporation is the process in which a liquid changes to a gas. Water vapor turns into clouds when it cools, condenses and attaches to particles in the atmosphere. When billions of these water droplets join together, they form a cloud. When clouds get so full of water that they can’t hold any more, the water falls back to the ground as precipitation.
This experiment will demonstrate that process.
- Start by poking several holes into the bottom of the plastic cup.
- Fill the plastic cup with cotton balls.
- Put the plastic cup on top of the glass jar.
- If you’d like, add food coloring to the water.
- Pour water over the cotton balls.
- When the cotton balls or clouds get so full, it will start to rain.