UTAH (ABC4) – After a week of thunderstorms and summer monsoon activity, Utahns who weathered the storms were rewarded with a special sight on Wednesday — perfect double rainbows.

All across the Wasatch Front and Salt Lake Valley, ABC4 viewers who were in the right place at the right time were able to witness plenty of colorful stripes dancing across Utah skies.

Take a look at these images captured by ABC4 readers:

  • Double Rainbow
  • Double Rainbow
  • Double Rainbow
  • Double Rainbow
  • Double Rainbow
  • Double Rainbow
  • Double Rainbow
  • Double Rainbow

Have you ever wondered what actually causes the eye-catching phenomenon?

According to the National Weather Service (NWS), it’s actually a simple reflection.

To understand the phenomenon of a double rainbow, it’s important to understand how a rainbow is initially formed.

“As light enters the raindrop, it is refracted (the path of the light is bent to a different angle), and some of the light is reflected by the internal, curved, mirror-like surface of the raindrop, and finally is refracted back out the raindrop toward the observer,” says NWS. “This schematic represents the path of one light ray entering a raindrop at point A. As the light beam enters the surface of the raindrop, it is bent (refracted) a little and instead of continuing to point D, strikes the inside wall of the raindrop at point B, where it is reflected back to point C.”

Raindrop reflection diagram (Courtesy of NWS)

A double rainbow can be formed when sunlight is reflected twice within a raindrop, essentially a reflection of the initial reflection.

When viewing a double rainbow, you’ll notice the rainbows aren’t actually identical — one rainbow runs in the typical order of red, yellow, green, blue, indigo, and violet. The second rainbow is a complete reversal of that classic pattern.

“The rainbow we normally see is called the primary rainbow and is produced from one internal reflection,” explains NWS. “The secondary rainbow arises from two internal reflections and the rays exit the drop the second time at an angle of around 50 degrees, rather than the 42 degrees for the primary rainbow” resulting in a second rainbow.

NWS says it’s even possible for additional rainbows to be reflected but these are not as commonly witnessed.

So although it appears quite inexplicable, the next time you spot this phenomenon, you’ll know it’s only a matter of simple science and not the magical manifestation of a leprechaun.