What causes a double rainbow?

A single rainbow is a beautiful sight to behold, but a double rainbow is even more rare and spectacular.

You may have been lucky enough to see one first-hand, but if not, then you can witness the double rainbow’s awe-inspiring effects in Yosemitebear62’s infamous viral YouTube video.

Whilst this colourful natural phenomenon may not leave you sobbing with glee, you may still be wondering, what does it all mean?

Double Rainbow
A double rainbow forms when light refracts twice within water droplets suspended in the air

A single rainbow forms when sunlight bounces off of the inside of water droplets suspended in the air. However, if the light bounces multiple times, more rainbows form.

It is thought that larger water droplets that have been flattened by the surrounding air are needed to form double rainbows. These so-called ‘burgeroid’ droplets have a larger surface area for reflecting light more than once.

If the light bounces three or four times, tertiary or quaternary rainbows form, but they are usually too faint for the naked eye to see.

Check out our video below to find out more about how double rainbows form…

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You can also take a look at:

Create your own rainbow with our home science experiment

The How It Works Book of Extreme Weather 

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