chris_m_ller

all rainbows are by nature/physics double - the second one, which in which the spectum is inverted is usually harder to spot as it is fainter (the internal reflection isnt as efficient in this case) - the pot of gold is located at a point between the two, tending towards the brighter one, you have to figure out the ratios of the two brightnesses and convert that to a distance along the line connecting the terminating points between them - the terminating point is the section that is 565 nm in wavelength, basically this is the cusp of green and yellow.

I was going to say that perhaps the pic could be rotated a degree CW to align the shade to the horizontal - but there it is in the photo, the hand just about to it for me... very nice... The black in the lower half of the pic is mottled a bit by the jpeg compression tho, I can perhaps see this as I am viewing on an LCD, most mid to higher end pic progs such as photoshop can set black to true black, otherwise the scanner settings may help - cheers!