M. Minnaert (1893–1970)

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Unparalleled as an accessible, accurate and practical source to discovering the many common and rare optical phenomena visible in the sky. Would-be ufologists and conspiracy theorists would be well advised to start here.

A bit technical, so this isn't for children, but a really interesting look at various phenomena of light and colour. The author looks at not just shadows, rainbows, and mirages, but delves into the whys and wherefores of things like interference colours in ferruginous water, how colours are affected by humidity, etc.

This is a super interesting book. There was simultaneously too much math for me (I'm a math lightweight), and also parts of it felt too speculative. I wonder if that's just a factor of when it was (originally) written. Still, what I read of it was broken up into quite short digestible chunks, and there were some really interesting insights even in just the first few chapters.