I Can Sing A Rainbow Three

I haven’t been contributing to the blogosphere as frequently as readers may have liked; at least I haven’t been doing so on this blog, but I have been picking fights with writers elsewhere.

But I'm back – and firstly want to tie up the remaining issues around the spectacular rainbows above Camberwell. You will remember I wondered why rainbows should be so bright above South London’s number one murder hotspot.

I have had a fascinating reply from Douglas [no matter that he is my uncle and a bit brainy] and quote it below;

"Your grand rainbows are, almost certainly, due to the amount of airborne particulate in the air over the conurbation, carbon in particular. Carbon refracts the visible red in the spectrum more than the other colours. Red is generally the easiest of the rainbow colours to see in the sky, an effect that is added to by the inner, second rainbow having its colours reversed and therefore the two red bands nearest one another. But carbon is the key. You can carry out a simple experiment that is an analogue of the refraction of light through a saturated atmosphere. Take a clear glass bottle, fill it with water and add a few drops of milk to make it cloudy. In a darkened space, shine a bright, white light through the colloidal suspension towards your eyes. You see the light slightly bluish. Shine the light through the bottle from the side (at right angles to your line of vision). The light now has a pinkish tinge. The blue light has been refracted least and the red most, just like in a rainbow."

I have to say I am one of those Dads who love this kind of experiment; ripping open self-seal envelopes in the dark, and hitting sugar cubes with a hammer, are the fun way to learn. It's sad that the current political climate bars us from making small, safe, garden fertiliser based fireworks in the back garden. Welcome to Blair's Britain...

So my thanks go out to Douglas for his solution; Poincarre's Conjucture coming soon I hope?

Andrew Mishmash