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Harringay, Haringey - So Good they Spelt it Twice!

As we were heading out last night, we spotted a wonderful rainbow over Harringay. I didn't have my camera with me but grabbed this iPhone shot at the top of Allison. (I didn't realise till a bit later that it was in fact turning into a double bow, so sadly clipped most of the upper bow.

Was anyone out and about with a proper camera yesterday evening?

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I took this one of the double bow from the top of Pemberton - sadly only from my phone so not as clear as it might have been.

Yes, that got it. It's particularly noticeable in your photo how the rainbow is lighting up the sky beneath it. I f I hadn't seen it myself, I'd almost think that the sky above and below the main bow were from different photos.

Good point, I hadn't noticed that!

Actually, I've never noticed before that the colours in the second bow are reversed.

Ah ha, proof that it is a second bow and not Photoshopped!

That, Kate, would be having a second bow to ones fiddle.

Which makes ones wonder if it's sone sort of a reflection of the first.

It's all to do with the angle at which the rays hit the rain.

The light splits in different directions ( I guess )

Thanks for these photos. Have you ever seen a moon rainbow ? And there's another phenomena called an 'earthquake rainbow' which apears just before an earthquake. And while i'm at it check out another opitical phenomena called 'Glory'. I won't bother to google these, i'll leave that to you.

Any physics teachers out there to check if I have got this right?

Each rain drop is a sphere which reflects light back from the sun, the sun needs to be behind us, (and our shadow in front).

However if we are at an angle of 42 degrees to those raindrops we see that reflected light split up as if it is going through a prism.  Some of the light from the sun hitting the spherical rain droplets will be bent (refracted) as it enters the raindrop, it will bounce off the back of the rain droplet, and is bent again as it leaves. 

Sun light is made of different wavelengths (colours) travelling at different speeds and they react differently to being bent, e.g.  blue light bends more than red light, so will reach the edge of the raindrop in a different place, because of this we are then able to see them as different colours.  The water droplets we are viewing at an angle of 42 degrees will appear as red to us and those viewed at an angle of 40 degrees will appear as blue (with the different related angles and colours in between).

Underneath the rainbow the sunlight reflected back from the raindrops is at angles of less than 40 degrees, this light is also made up of different colours but we don't see the effect of them being split as through a prism as we are at the wrong angle of view, the colours cancel each other out and appear as white light.

Almost right. The light is refracted first (and split into the different colours) and then reflected off the back of the raindrop before being refracted once more as it exits. That's what makes the primary bow. 

The secondary bow is formed the same way except that before the refracted (coloured) light exits it reflects once more off the back of the raindrops, reversing the direction of the colours.

The second bow is formed by raindrops higher up in the sky. This is because the sunlight that forms the first bow comes into the raindrops from the top, whereas the sunlight that forms the second bow comes into the raindrops from the bottom (which is why it can reflect twice inside the raindrops).like this

Thank you both for that.

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