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Grass rainbow

I was walking through the garden in the morning and saw these coloured dew drops on the grass. I stopped to think about how they were formed. I should point out from the start that I am the wrong person to be writing about this because I'm colourblind. I can see a few blue drops and lots of yellow ones but no red or green probably nobody can see the green ones but I'm guessing there may be some red. The colours are formed in the same way as the colours in a rainbow, by refraction in the water drops. But I have some questions.

Why are there only yellow and blue drops? (there probably are red and green ones but I can't see them)

Why are there so few blue drops compared to yellow?

Why don't the droplets form circles like a rainbow? (I would think there should be some circular symmetry but there doesn't appear to be.)

This would make a nice EE topic.

Blog post on rainbows

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