Look carefully at this photo of a rainbow over Dinas Head near Fishguard in Wales (above) and you will notice that as it nears land it looks like there is a sharp bend in its arc. What caused this?
• This effect is caused by atmospheric refraction, the same type that makes the sun appear to rise earlier and set later than would be expected from astronomical calculations.
The density of the atmosphere decreases the higher you get above Earth’s surface, and so it interferes less with the light passing through. This means the speed of light is slightly faster higher…
