Double rainbow spotted in Tai Po

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5th August 2022 – (Hong Kong) This morning, a rare double rainbow appeared in ​​Tai Po at about 8am. Many netizens shared the pictures on Facebook. They were spotted near Tai Yuen Estate, Tai Wo Estate etc.

A double rainbow is a wonderful sight where you get two spectacular natural displays for the price of one.

Surprisingly, this phenomenon is actually relatively common, especially at times when the sun is low in the sky such as in the early morning or late afternoon. The second rainbow is fainter and more ‘pastel’ in tone than the primary rainbow because more light escapes from two reflections compared to one.

The secondary rainbow is also dispersed over a wider area of the sky. It is nearly twice as wide as the primary bow.

A key feature of double rainbows is that the colour sequence in the second rainbow is reversed, so instead of red, orange, yellow, green, blue, indigo and violet (ROYGBIV), the colours appear in VIBGYOR order.

The dark band between the two rainbows is known as Alexander’s band, after Alexander of Aphrodisias who first described it in 200AD.

The band forms because between the deviation angles of the primary and secondary rainbows none of the sunlight is scattered by the raindrops towards the observer giving the band of dark sky.

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