Model of Water Cycle

INTRODUCTION

This model clearly illustrates that the amount of water on the earth does not change with time. It just cycles from ocean to the atmosphere and then descends back to landmasses in the form of rain. This model helps explain that we are indeed potentially drinking and bathing in the same water as used by the ancient Romans or even by the dinosaurs.

MATERIALS

Water cycle model (Fisher Science Education CVS45140A)
60 Watt Light
Water
Salt
Ice

WHAT TO DO

Add salt water to fill the sea portion of the water cycle model.
Cover the base of the model with its clear plastic cover. Make sure the cover is pushed down tightly against the base.
Position a light bulb (60 Watts or greater ) above the ocean portion of the model. Make sure the light bulb is at least 2 inches above the clear plastic cover. Positioning the bulb closer may cause the cover to warp slightly and not seal well at the edges.
Add ice to the cloud portion of the plastic cover of the model. Make sure the cloud continues to have ice in it throughout the experiment.

The model is working as soon as the light bulb is turned on. The evaporation of the ocean will only become noticeable after a significant amount of water has evaporated. However, with time you should be able to see water dropping from the cloud and into the freshwater lake. It may take up to three hours before the cycle is completely observable. After the lake has filled with water, ask a student to compare the taste of the water from the lake and ocean.

EXTENSION

This model can also be used to study acid rain formation by placing a dilute acidic solution (vinegar works well) in the ocean portion of the model.

SOURCE

"How Science Works." J. Hahn, Dorling Kindersley, London, 1991. ISBN 0-7621-0249-7
"Science Is . . . A Source Book of Fascinating Facts, Projects and Activities." Susan V. Bosak, Scholastic, 1991. ISBN 0-590-74070-9.
Information supplied with the water cycle model.

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