Water, Water, Everywhere

From:  http://www.units.muohio.edu/dragonfly/water/experiment.shtml

Dragonfly Miami University Oxford, Ohio 45056

WHAT YOU WILL NEED:
A large, clear bowl
Plastic wrap
A weight
A smaller container  (a cut-down yogurt cup works well)
A rubber band or piece of string

WHAT TO DO:

 Place the small container in the middle of the large, clear bowl. Fill the bowl with a little water, being careful not to fill the small container inside. Cover the bowl with plastic wrap, and fasten the plastic wrap around the rim of the bowl with your rubber band or string. Put a weight on top of the plastic wrap in the center. (See figure below.) Now put your contraption on a window sill or somewhere that the sun will hit it.

   How long does it take for water to evaporate and condense on the plastic wrap?  Where does the water go after it condenses on the plastic wrap?

WHAT'S HAPPENING?

    The heat of the sun evaporates the water, which rises, condenses on the cool plastic, and falls into the small container.  You've created a small-scale replica of the water cycle that occurs on Earth!
 
Now that you've made a mini water cycle, you can use it to conduct your own investigations. Here are some ideas:

Some people are worried about the effects of pollution on the Earth's polar ice caps. If particles in the air make the white ice caps darken, the ice caps might melt. How do you think discoloration would affect your water cycle? Would dark-colored water evaporate more quickly or more slowly than plain water? Find out! Try making two water cycles: one with regular water and one with water tinted with food coloring. Which do you think will evaporate faster? Why? What happens?

Is air temperature or water temperature more important to evaporation? First, make some predictions about what you think and why. Then to investigate, use warm water in one water cycle system and cold water in the other to see which evaporates more quickly. Then compare evaporation in one system that sits in a cold room and another system that sits in a warmer room. What happens?

Next, investigate how direct sunlight affects evaporation. Try placing one water cycle system in the sun and one in the shade. What do you discover?

Does ice evaporate in cold weather? If you live in a cold climate, try making a water cycle with ice chips--instead of water--and put the water cycle system in the sunshine on a cold, clear day. Would you see any signs of evaporation? Why?

Try creating your own investigations!

If you do an investigation using your homemade mini water cycle, let us know what you learned! Write to us at:

Dragonfly
Miami University
Oxford, Ohio 45056

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