It is even possible to see triple or quadruple rainbows, but these are rare. A rainbow is created when a ray of sunlight passes through a drop of water. The water droplet refracts the light at lots of different angles, with the effect that the ‘white’ or invisible light is shown to be made up of all different colours.
While the first rainbow is visible when light is reflected once off the back of a raindrop, the second (usually more pale) rainbow is seen when light is reflected twice in a more complicated pattern.
The colors of the second rainbow are inverted, with blue on the outside and red moved to the inside. The second bow appears dimmer or cloudier because much more light is released from two reflections, and both bows cover a larger portion of the sky.
Here are the best shots of double rainbows!