A grey rainbow is not a scientifically recognized phenomenon. Rainbows are formed by the refraction and reflection of sunlight through water droplets in the atmosphere, resulting in a spectrum of colors. It's possible that you're thinking of a monochromatic rainbow, which is a rainbow that appears as a single color, often white or grey. This can happen in a few situations: - Dim Lighting: If the sunlight is weak or diffused, such as dur