Weather Science Projects

The Water Cycle

In this experiment, you will see how water from the ground gets into the air to form clouds and then falls back to the ground as rain!

What You Will Need:

• paper cup
• plastic zip-top bag (large enough to hold the cup standing up)
• tape
• water

What To Do:

1. Fill the cup about 1/4 full with water.
2. Carefully set the cup inside the plastic bag and zip it closed.
3. Tap the bag with the cup inside to a window where a lot of sun comes in.
4. Check your cup and bag throughout the day and watch what happens.

What's Happening?

As the sun heated up the water in the cup, some of the water evaporated into a gas called water vapor. You can't see water vapor, but you can see what happened next. The water vapor turned back into a liquid and little drops of water formed on the inside of the bag—this is called condensation. When several droplets of water stuck together, they became heavy enough to pull each other down the sides of the bag. If you left this project taped to your window for long enough, all of the water from inside the cup should eventually end up in the bottom of the bag!

This is exactly how clouds form and make rain. Water from rivers, lakes, streams, or oceans evaporates into the air when it is heated up by the sun. As the water vapor rises up in the air, it condenses, or starts to cool down and turns back into a liquid. Then, droplets of water start to stick together as clouds. When enough droplets stick together in the clouds, they become large and heavy and are pulled down towards the earth by the force of gravity. When water drops fall from clouds, it is called rain. Sometimes the droplets freeze before they get to the ground and become hail, sleet, or snow!

Cloud in a Jar

Did you know you can make a cloud? It will be much smaller than the ones in the sky that bring us rain, but it forms in the same way as those in the sky.

What You Will Need:

• a glass jar
• black paper
• tape
• warm water
• ice cubes
• small metal bowl or a metal baking sheet (should completely cover the opening of the jar)
• a match
• a flashlight (optional)
• an adult to help

What To Do:

1. Cut the black paper to fit halfway around the jar, leaving about one inch of space at the bottom of the jar. Tape it in place on the jar.
2. Add about two inches of warm water to the jar.
3. Fill the metal bowl or tray with ice cubes.
4. Have an adult light a match and hold it inside the jar for a few seconds and then drop it into the water.
5. Quickly cover the jar with the container of ice.
6. Look into your jar from the open side (so that the black paper makes a background at the back of the jar) and watch what happens.
7. You should start to see a cloud form! As the cloud gets bigger, it will be easier to see. To see the cloud even better, turn off the lights and shine a flashlight into the jar towards the black paper.
8. After watching your cloud for awhile, you can take the container of ice off of the jar and watch the cloud rise up and disappear!

What's Happening?

Clouds are formed when water warms up and changes into a gas called water vapor, which rises up into the air. As it rises higher in the sky, the water vapor cools down and turns back into tiny drops of liquid. Inside the jar, some of the warm water evaporated into water vapor. Then, as water vapor hit the cold metal bowl of ice, it turned back into tiny droplets of liquid water. The smoke from the match that was held in the jar helped make the cloud easier to see. The tiny droplets of water stuck to tiny bits of smoke in the air between the warm water and the ice. In a real cloud, tiny pieces of dust floating in the air work the same way as the smoke did in your jar, and the water droplets form around the dust. As more water changed into water vapor and then back into tiny water droplets, the cloud grew.

When you removed the container of ice, the water vapor didn't condense back into drops of water anymore, but just rose out of the top of the jar, taking your cloud with it!

To learn more about baby animals, visit this Teaching Tip.

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