Double Rainbow – Great Barrier Island

double_rainbowI was waiting for the best moment to step out of the warm cabin to walk through the muddy path to my kitchen and prepare a feed. Three days of heavy rain and gale-force winds had fine-tuned my observing skills to ‘forecasting’ those brief moments where I could go outside without being exposed to the worst of the storm.

So how is this for timing? Once again, the calm after the storm, this time with a double rainbow. Have a close look at the picture and you will notice… Have a look first!

You’ll notice that the sky seems significantly brighter underneath the first bow. Further, you can see that the colours of the second bow are inverted. I admit, I’ve seen and taken pictures of double rainbows but never noticed the colour inversion. It is so obvious though.

A rainbow is an optical and meteorological phenomenon that is caused by both reflection and refraction of light in water droplets resulting in a spectrum of light appearing in the sky (source Wikipedia). Multiple rainbows are the result of multiple reflections of sunlight inside the raindrops, and it comes to no surprise that the colours of the second rainbow are inverted compared to the primary bow as a result of the second reflection. Also no surprise that it is fainter.

The so-called Alexander’s band is not well defined in this image but noteworthy to mention that this guy described this phenomenon in 200 AD.

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