Compose a descriptive sentence about the given input.
A rainbow
A rainbow is a meteorological phenomenon that appears as a multi-colored arch in the sky, caused by the reflection, refraction, and dispersion of light in water droplets.
Complete the following task based on the instruction and optional input provided.### Instruction:
Compose a descriptive sentence about the given input.

### Input:
A rainbow

### Output:
A rainbow is a meteorological phenomenon that appears as a multi-colored arch in the sky, caused by the reflection, refraction, and dispersion of light in water droplets.