On those special days when the sun continues to shine while rain falls, we can sometimes see a rainbow! Other times a rainbow will appear from the mist of a garden hose while watering plants or spraying a sibling or friend!
But what makes rainbows form? Why can’t we always see one when it’s raining? Try this experiment to create a rainbow of your own to learn how and why we see them when we do.
Materials
A clear glass bowl
A mirror that fits in the bowl
Water
White paper
Sunlight
Instructions
Wait for a sunny day.
Place the mirror in the bowl facing the sun. Lean it against one side so it rests at an angle.
Add water to the bowl until the mirror is halfway submerged.
Sit with your back to the sun facing the mirror. Hold up the piece of paper and move it around until you “catch” a rainbow on it.
Move the paper closer and farther from the mirror to see how the rainbow changes.
How it works
The bowl of water and mirror represent a raindrop or mist droplet. When sunlight hits a drop of water, it refracts, or bends.
Sunlight may look white, but it’s made of many different colors. And each of those colors has its own wavelength. Those wavelengths refract at different angles, showing off the different colors.
Try turning the mirror away from the sun. It doesn’t work anymore because the sunbeam isn’t shining through the water anymore. Storm clouds can block the sun so rainbows don’t form. If conditions seem right but you don’t see a rainbow, try looking in a different direction. Make sure your back faces the sun.
What happens if you add more water or take some away? Does anything change if you use a different sized or shaped mirror?
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