The breathtaking spectacle of a rainbow! It's a natural wonder that has fascinated humans for centuries. Here's a step-by-step explanation of how a rainbow forms:

**The Basics**

A rainbow is a curved arc of light that appears in the sky when sunlight interacts with water droplets in the air. The color of the rainbow depends on the angle at which the light hits the droplets.

**The Rainbow Formation Process**

Here's what happens when sunlight passes through a raindrop:

1. **Light enters the atmosphere**: When sunlight enters the atmosphere, it passes through the air and reaches the surface of the Earth.
2. **Water droplets scatter light**: As the light passes through the air, it encounters water droplets suspended in the air. These droplets scatter the light in all directions, but they scatter it in a specific way.
3. **Scattering occurs**: The light that is scattered by the droplets is called Rayleigh scattering, named after the British physicist Lord Rayleigh. This scattering is responsible for the blue color of the sky.
4. **Scattering increases as the angle of incidence increases**: As the angle of incidence (the angle at which the light hits the water droplet) increases, more light is scattered, resulting in a longer wavelength of light (red).
5. **The light reaches the observer**: The scattered light reaches the observer's eye, which is sensitive to the longer wavelengths of light