Raindrops bend (refract) light rays from the Sun, acting much like prisms by splitting the light into its seven component colors. Each color emerges again at a slightly different angle depending on its wavelength, producing separate bands of color. Red (the longest wavelength) appears on the outside of the rainbow, followed by orange, yellow, green, blue, indigo, and violet. The higher the Sun is in the sky, the flatter the rainbow. A double rainbow occurs when light is reflected within the raindrops.

When sunlight hits water droplets in fog an almost colorless fogbow results. The lack of color is due to fine water droplets of fog not dispersing light as well as larger droplets.

Green Flash

A green flash can occur at sunrise or sunset when some part of the Sun suddenly and briefly seems to change color from red or orange to green or blue. This is an optical effect caused by the larger refraction of light at the blue/ green end of the spectrum.