water vapour absorbs light and more blue gets through hence everything a long way away looks blueish and the sky is a long way away
Not correct.
An oxygen molecule is about the size of the wavelength of blue light. This means that the blue part of the sun’s light is scattered around much more than the rest of it. It gets scattered around randomly, so the blue photons are bombing around all over the place and they can hit your eyes from any angle. Hence, when you look up at any angle you get blue photons, and then you see blue. The sun’s light is actually white, but because some of the blue is scattered around, it looks yellow from down here.
At sunset, the sun’s light goes through more oxygen (it comes at a lower angle to you) so more blue is scattered, and hence the sun looks redder. However, the light is also going through a lot more dust in the atmosphere (because the dust is mostly low down) which scatters the red light, so by the same token you get red photons coming from all angles.
Curvature of the earth is clearly visible on a clear day on the beautiful Aberdovey to Barmouth road on a very clear day. I can see three islands on the Lleyn, I thought there was only one.. keep driving, they aren’t islands…