Rainbows appear when sunlight interacts with water droplets. The core process behind their formation is called refraction.
Understanding Rainbow Formation
Here's how it happens, step-by-step:
- Sunlight Enters Raindrops: When sunlight, which is white light, enters a raindrop, it doesn't just pass straight through.
- Refraction Occurs: As the light passes from the air into the denser water droplet, it changes direction. This bending of light is what we call refraction.
- Colors Separate: Because each color in sunlight has a different wavelength, they each bend at slightly different angles when they refract. This separates the white light into its component colors, like the ones seen in a rainbow.
- Reflection Inside the Drop: The separated light now reflects off the back surface of the raindrop.
- Second Refraction on Exit: As the light leaves the raindrop, it refracts again. This second bending of light further separates the colours.
- Rainbow Appears: The light exits the raindrop towards your eyes, and since countless raindrops are doing the same thing, you see a full spectrum of colors in the form of a rainbow.
Factors Affecting Rainbow Visibility
- Water Droplets: Rainbows are typically seen during or after rainfall when there are water droplets in the air. They can also be seen near waterfalls or when misting water with a garden hose.
- Sun Position: The sun needs to be behind you, and the water droplets in front of you to see a rainbow. This means rainbows are mostly seen in the morning or late afternoon when the sun is low in the sky.
- Observer's Perspective: The position of the observer is also vital. Different viewers see the same rainbow from slightly different perspectives, so technically, the rainbow each person sees is unique.
Key Takeaways:
- Refraction is Key: Rainbows are formed when sunlight is refracted and dispersed by water droplets.
- Color Separation: The varying wavelengths of colors are separated by refraction.
- Specific Conditions: The right mix of sunlight, water droplets, and viewing angle are necessary to observe a rainbow.
This explanation is based on the understanding that rainbows are formed when light from the sun is scattered by water droplets (e.g. raindrops or fog) through a process called refraction. As the reference states, "Refraction occurs when the light from the sun changes direction when passing through a medium denser than air, such as a raindrop."
