Saturday, September 20, 2008

The upside-down rainbow, and other science news

(a) Atoms 1, Smasher 0

(b) Europe to collide with asteroid

(c) What people think affects what people think

(d) Upside-down rainbow coincidence:

So, I’m sitting in the garden with my dad, a bit past 4 this afternoon, and he holds up his local paper to show me a story: there’d been an upside-down rainbow visible over Cambridge the other day, which he’d seen himself. I asked him how that would happen, and he leant back in his deckchair to formulate the answer, but then said: “My god!” I asked what, and he pointed up:

Unlike normal rainbows, it was in the same direction from us as the sun, although higher up. You can see the sky getting lighter in the direction the trough points. It lasted for about half an hour after we first noticed it.

Apparently it’s something to do with rare ice crystal formations in the upper atmosphere, which can refract sunlight differently to the way that raindrops more usually do. The technical term for an upside-down rainbow is a circumzenithal arc. Cool. (It also got coverage in a fair few national papers too. And find out more rainbology here.)

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