Jun. 17, 2010

Water Cycle

by Lynn Brunelle

It’s Raining, It’s Pouring!

It’s that time of year when some days are beaming with sunshine one minute and the next there’s a big black cloud dropping rain overhead. So what’s that all about? The water cycle. It’s all about the water cycle. Check these experiments out. You can make a cloud and make it rain right in your own kitchen.

Make it rain inside

Why does it rain? You can make it rain right in your own kitchen and see for yourself.

What You Need

  • A pop bottle
  • Scissors
  • Hot tap water
  • Ice

What You Do

  • Get a grown up to help you cut off the top part of your pop bottle at the shoulder, leaving the cap screwed on tightly.
  • Fill the bottom part of the bottle half full of hot tap water.
  • Turn the top part of the bottle so it’s upside down, and fill it with ice. Set this into the bottom part of the Pop Bottle and wait.
  • What do you notice?

What’s Going On?

You made a miniature water cycle--evaporation, condensation, and precipitation-- right in your bottle.

Heat causes the water to evaporate. Liquid water turns into a water vapor gas that rises into the air. When it rises it hits the ice and cools down. The cooling water vapor molecules start to stick to each other and make a cloud. This is called condensation.

Clouds collect water droplets until all the droplets are too heavy to float in the air. Then water falls from the sky as rain. This is called precipitation. In your bottle, the droplets get heavier and heavier until they fall back down into the bottom part of the bottle.

The water cycle happens every day over and over all over the Earth, on a much bigger scale.



Cloud in a Bottle

What are clouds made of? More than you think. Try this and see.

What You Need

  • Black construction paper
  • Hot tap water
  • A pop bottle
  • Matches—and a grown up to help out

What You Do

  • Prop up the black construction paper on your kitchen counter. You will use the paper as background later on.
  • Dribble about 2 inches of very hot water into your bottle—but don’t melt it!
  • Quickly cap the bottle.
  • Shake the bottle for about 1 minute.
  • Put the bottle on the counter. Have a grown-up strike a match. Let it burn for about 2 seconds. Blow out the match. Quickly uncap the bottle, and drop in the match and cap up the bottle again.
  • Put the bottle on its side in front of the black paper so you can see what’s going on inside the bottle more clearly. Push on the side of the bottle as hard as you can for about 10 seconds to pressurize the inside. Let go and see if you have a cloud. If not, repeat this until you see a cloud form in the bottle.
  • After you get a cloud. Put the bottle right side up and uncap it. What happens to your cloud?

What’s Going On

Clouds are made of more than just water vapor clinging to itself. The water vapor needs a little something to hang on to. Something like particles of dust. In this experiment, the cloud began forming in the bottle when the water vapor in the air attached themselves to the particles from the smoky, sooty, match.

About Lynn Brunelle

Lynn Brunelle is a four-time Emmy Award-winning writer for the television series Bill Nye the Science Guy. An editor, illustrator, and award-winning author, Lynn has created, developed, and written projects for PBS, NPR, and Disney, among others.

The views expressed are those of the author and are not necessarily those of Science Friday.

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