What Makes the Colors in a Rainbow?
After a shower of rain there is often a rainbow. Rainbows form when the sun begins to shine through the clouds while the air is still filled with raindrops. The raindrops act as tiny prisms to separate the light into the colors of the spectrum, and an arch of colors appears in the sky.
The many colors in a rainbow blend into each other so that we rarely see more than four or five clearly. You’ll miss if it you face the sun. A rainbow can only be seen if you face the sky with the sun at your back. Little rainbows can often be seen in the spray of a lawn sprinkler.
Rainbows happen when sunlight and rain combine in a very specific way. The beams of sunlight separate into the colors we see in the rainbow as they enter a raindrop. Sunlight is actually made up of different colors that we don’t usually see.
When a beam of sunlight comes down to Earth, the light is white. But, if the light beam happens to hit raindrops on the way down at a certain angle, the different colors that make up the beam separate so that we can see them — in the form of a rainbow.
The angle for each color of a rainbow is different, because the colors slow down at different speeds when they enter the raindrop. The light exits the raindrop in one color, depending on the angle it came in, so we see only one color coming from each raindrop.
Light at different angles coming through many raindrops form the rainbow that we see, in stripes of red, orange, yellow, green, blue, indigo and violet.
In fact, our eyes can discern many more individual hues. Rainbow colors are not “pure”. The classical rainbow is made up of overlapping bows of individually pure spectral colors. The final colors that we see are mixtures.