Rainbows are optical illusions that result from the sun’s rays shining through moisture in the atmosphere. A full rainbow is actually a complete circle, but from the ground we see only part of it. Perhaps under the right conditions, you could see the entire circle from an airplane.
A double rainbow occurs when water droplets reflect the sun’s rays twice and attain the same effect. While a primary rainbow is visible when light is reflected once off the back of a raindrop, a secondary and usually dimmer rainbow is spotted 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.
In Hawaii, we have a saying, “No Rain, No Rainbows!” The next time you feel a frown forming over a few rain drops, look to the sky … you just may catch a spectacular double rainbow!