Water Cycle - Activities

Activity:  Making a Rainbow

Materials:  a glass of water         a sheet of white paper                  a sunny window

Procedure:

• 1.  Place a glass of water on a window ledge in bright sunlight.
• 2.  Place a sheet of paper on the floor.

Observation:

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Conclusion:
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Why: 

You see the colors of the rainbow.  You are separating the various colors that make up white light.  When light passes at a slant from the air through the glass of water, the rays change direction – they are “refracted.”

Each color bends differently:  violet bends the most and red the least.  When the light comes out of the glass of water, the different colors travel in slightly different directions and strike the sheet of paper at different places.  It is the same with a rainbow in the sky.  It is simply a curved spectrum, made when sunlight shines through water drops in the air at an angle of between 40 and 42 degrees with the horizon.  The water drops bend the Sun’s rays.  The sun has to be behind you if you are going to see a rainbow in the sky.  You will only see a rainbow in the morning, when the Sun is shining in the east and showers are falling in the west – or in the late afternoon, when the Sun is shining in the west and showers are falling in the east.  The arc you see from the ground is just a part of the rainbow.  If you are flying in a plane you may see a rainbow’s full circle.