Rare ‘tertiary rainbow’ appears over Chesterfield after evening showers

Sharing the picture with the Derbyshire Times, reader Kei Kei Chung Li said the tertiary rainbow appeared in Brampton on Monday evening during a break in the heavy rain.

There have only been five scientific reports of this type of weather phenomenon in the past 250 years, according to the international scientific body the Optical Society.

Triple, or tertiary, rainbows usually occur when the sun is low on the horizon and there is a large body of water nearby.

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A regular rainbow happens when sunlight is refracted through water droplets, usually rain drops, splitting the light into the spectrum of colours.

Sunlight reflecting internally within raindrops is what makes a double rainbow possible, with the second arc appearing with the revese colours from the first.

But, rays leaving raindrops after three reflections is what makes a triple rainbow, with the third arc pointing towards the sun.

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