Rainbows are one of nature's most spectacular displays. They appear when sunlight shines through countless tiny water droplets suspended in the air after rain or near waterfalls. The sun acts as a natural light source, sending white light toward these water droplets, which then create the beautiful arc of colors we see in the sky.
Sunlight appears white to our eyes, but it's actually composed of all the colors of the rainbow mixed together. This can be demonstrated using a triangular prism. When white light enters the prism, it bends and separates into its component colors: red, orange, yellow, green, blue, and violet. This separation occurs because different colors of light bend by different amounts when passing through the prism material.
When sunlight hits a water droplet, it follows a specific path that creates the rainbow effect. First, the white light enters the droplet and bends due to refraction. Inside the droplet, the light travels to the back surface where it reflects internally. Finally, the light exits the droplet, bending again through refraction. At each step, different colors bend by slightly different amounts, causing the white light to separate into the spectrum of colors we see in a rainbow.
The rainbow always appears at a precise angle from the observer's perspective. This angle is 42 degrees from the antisolar point, which is the point directly opposite the sun from the observer's position. Red light emerges from water droplets at exactly 42 degrees, while violet light emerges at about 40 degrees. This slight difference in angles for different colors creates the rainbow's characteristic arc shape, with red on the outside and violet on the inside.