colours in nature – how to make a rainbow

In the third of my colour in nature series, I look at how nature creates a rainbow and its many colours.

rainbow recipe
There are two ‘ingredients’ needed in order for us to see a rainbow;
1. The sun (positioned behind you) and
2. Raindrops

When the water droplets are suspended in the atmosphere, each of them act as a tiny prism.  When the sun shines through these droplets, light is refracted and there you have it, a rainbow! Whether a rainbow’s colours appear bright or pale will depending on the size of the water droplets.

Single rainbow over Carmel Beach, California.

A rainbow reflected in Arctic icy waters in Canada's Foxe Basin.

double rainbows
If you’re lucky enough to see a double rainbow this is when two reflections of light within the water droplet occurs.  The intensity of colour of the second rainbow will be less and you’ll notice the colours are in reverse order.

A double rainbow stretches over the Denali Highway in Alaska.

the scientist
In the 17th Century, Sir Isaac Newton was the first to explain the rainbow showing white sunlight is actually a mix of colours which he demonstrated using a prism. A prism causes light to bend, change direction and giving seven colours.

the colours of the rainbow
The 7 different colours (wavelengths) of light of a rainbow are red, orange, yellow, green, blue, indigo and violet.

rainbow arc
The different colours (wavelengths) of light have different refractive indices which cause them to bend unequally, creating the rainbow to arc. We only see a semi-circle shape because the land literally gets in the way.  So next time you’re in an aeroplane and you see a rainbow, you may just get lucky and see a full circle rainbow.

symbolism
Rainbows are seen by many cultures to hold symbolic, spiritual meanings.  Research shows Native Americans believe rainbows are “Pathway of Souls”. It’s also seen as good luck with the Irish who have a saying there is a pot of gold that lies at the end of a rainbow. Legend say people of the Austrian Alps believed righteous souls go to heaven via the rainbow.

If you enjoyed reading this article, you may also like to read the others in this colour in nature series – why desert sands are different colours,  the changing colours of sunset

Source: atmosphere.mpg.de and coloursoftherainbow.com

Image credits: travelblog.org, photography.nationalgeographic.com