Geometry of a rainbow
The position of a rainbow is not random. Under the right conditions of sun and rain, the rainbow will appear at a specific position in the sky. The position is determined by the way the raindrops redirect the light. The different light components each leave the raindrop at a specific angle. For example, the red components leave the raindrops at an angle of 42° (in relation to the incoming light) and the blue ones at an angle of 40°.
Which of the two components is higher up in a rainbow in the sky?
Download the template and print it out. Draw a light beam for the red and the blue component for each highlighted raindrop in picture A. Orient yourself by the raindrop in the example. The sunlight beams run parallel, that is, horizontally toward each drop.
If you are unsure, click here to show a hint.
With the help of your drawing, check which colour of the higher drops reaches the eye of the observer. These are the components that we see higher up in the rainbow.