There are two main conditions for witnessing a rainbow. The first is that the observer must be between the sun and the water droplets. The water droplets can either be rain, mist from a waterfall, or the spray of a garden hose. The second condition is that the angle between the sun, the water droplets, and the observer’s eyes must be between 40° and 42°. Therefore, rainbows are most easily seen when the sun is close to the horizon so the rays striking the droplets are close to horizontal.