Bifrost Effect

Q. Why do fashion designers wear neutral black?

A. Because they're so over the rainbow.

Well, anyway, a rainbow is essentially a two-dimensional illusion which can be re-imagined as a three-dimensional object for the purposes of flying over it, finding bullion under it or walking across it to Valhalla.

If you actually built some big goofy under-powered concentric fluorescent tubes (and swathed them with translucent plastic mesh to soften the edges) then when actually flying over you would see red.

This would be because you'd forgotten to specify that the colours should be staggered.

Imagine Ragnar Shaggy-Legs as a friend of Dorothy. Imagine that, while she flies over, he looks up, and what he wants to see is a bridge in which the colours are laid out side by side; not a flat surface against the sky, but a curved surface with the same kind of distortion as is used in advertising logos painted on to stadium grass so that, to the camera, perspective is canceled and brand-recognition is maximised.

Of course, the red stripe would have to be on the side nearest to Ragnar, so as to account for the greater width of its projection into two dimensions. From Ragnar's perspective, it must look like a rainbow. From Dorothy's helicopter it must have equal stripes of all colours but, because of Ragnar's requirement, it will swell grotesquely towards the middle to compensate for the greater distance from the ground, and probably curve upwards at the edges a bit, too.

Budgetary constraints exclude the leprechaun's bank deposit.

This came to me while watching an under-rehearsed schoolgirl singing.