Ka ua lei māʻohu o Waiānuenue – “The rain of Waiānuenue that is like a wreath of mist”
(Wai-ānuenue in Hilo is also known as Rainbow Falls)
(ʻōlelo noʻeau, Hawaiian proverb and saying)
Hawaii's Special Rainbows
There’s just something about those vibrant beautiful rainbow colors painted across the sky that never gets old.
Wouldn’t it be great if you knew where a rainbow would appear ahead of time? Knowing where to look then actually finding a rainbow where you thought it would be feels like magic.
Put on your slippahs and pull out your camera, my fellow rainbow chasers, because I’m going to share with you the science behind what makes the formation of rainbows predictable.
Then, I’ll give you a three-step plan on how to predict where a rainbow will appear every time. No, for real kine.
The Colorful Science
Rainbows appear in predictable places. The key to knowing where one will appear is understanding the science of what causes a rainbow.
Sunlight is made up of many different wavelengths (think colors) of light. A rainbow is formed when sunlight bounces and bends off of the inside of water droplets in the air. Each wavelength in the sunlight reflects off of the inside of a water drop at its own unique angle, causing it to separate and fan out into an arc of colors.
The water can be anything from rain to fog to the misty spray from waterfalls or waves.
The Secret Key
Here’s the secret sauce to predicting where a rainbow will appear in the sky: The position of the rainbow is always at the same angle between the observer’s shadow and the rainbow’s arc.
Every color has its own specific angle of reflection but for the color red, that magic angle is 42 degrees!
Keeping this colorful science in mind, here’s how you can find a rainbow every time…
3 Easy Steps to Predicting Where a Rainbow Will Appear Every Time
1. Stand with the Sun at your back and the rain (or mist) in front of you
Positioning yourself between the Sun and the water in the air, allows the bright strong sunlight to bounce off of the water droplets and reflect back to your eyes.
2. Find your antisolar point
This will be the location where your head casts its shadow on the ground. The exact point, if you want to be picky, is where your eyes would be located in your shadow.
It’s called the antisolar point because it is the position on the exact opposite side of your head than the Sun; hence the shadow.
3. Look 42 degrees above your antisolar point
This will be the angle where the edge of the color red will form. It’s actually 42.4 degrees but let’s not get that deep today. All of the other colors will form below red.
That’s it! If the sunlight is strong and bright enough to reflect off of the water droplets back to your eyes, you will see a rainbow will form at 42 degrees.
What, you don’t believe me?
Ok, just for you skeptics, I made this video: (vid link goes here)
Tips and Tricks for Rainbow Hunters
How do you know exactly where 42 degrees is? Well… you know approximately where 45 degrees is right?? Hint: It’s slightly below that. Come on, keep up, *wink*.
Also remember, the 42 degree angle between the shadow of your head and the color red stays constant, so…
When the Sun is low on the horizon like in early morning or late afternoon, the shadow of your head will be far away from you on the ground, therefore the rainbow will be high in the sky.
When the Sun rises higher from the horizon, the shadow of your head will be closer to you, therefore the rainbow’s arc will be lower to the horizon.
If the Sun gets higher from the horizon than 42 degrees, the rainbow arc will be so low, you won’t be able to see it from flat ground.
What angle? 51 degrees! The color red in a primary rainbow forms at 42 degrees above your antisolar point and at 51 degrees for a secondary rainbow. It's actually 50.4 degrees but who's counting.
An interesting note is that a secondary rainbow’s colors form in reverse order than the primary rainbow so the color red will be at the bottom and violet will be at the top.
Just For You
Every rainbow is truly unique and special.
The light rays that form your rainbow are not the same light rays that form the rainbow someone else sees, even if they are standing right next to you. This is because your 42 degrees are slightly askew from someone else’s 42 degrees.
No one sees exactly your rainbow. Each rainbow is uniquely yours.
Go Rainbow Hunting
Rainbows bring joy, wonder, and appreciation of Hawaii’s beauty. They symbolize hope and inspire awe. The very act of looking up into the wide blue sky is healthy for the heart and mind.
I hope my short guide will bring more joy into your life as you look for your next rainbow and create more appreciation for our island home.