Mystery #4Tier 2-3light
How does a rainbow form?
A rainbow appears out of thin air, with no paint and no screen: a perfect arc of every colour, always when the Sun comes out during rain. Where do the colours come from, and why an arc?
Your guess
What do you reckon turns plain sunlight and falling rain into a band of colours?
There's no single magic word to type, have a go in your own words, then reveal the answer to see how close you got.
Make a guess to unlock the hints and the answer.