It is long time that I am looking for what physical reason explain this observation:
the sun ambient light between sunrise and midday is crispy, somehow whiter than that of the afternoon hours. In other words it is like that morning outdoor light is more similar to that of a white lamp, and that of afternoon more yellow and incandescent bulb -'like.
Even in more physics term, it seems that the morning light has a higher Temperature than that of afternoon. Note that I refer to the T of an emitting black body, not the temperature as colloquially used in fashion, art, etc that goes right the other way around.
For those just a bit familiar with photography, is as the golden hours of morning and afternoon are not identical (the obvious opposite casting of shadow is obviously not part of the matter), like if the source of lighting changes (obviously the sun doesn't, so it is an atmospheric phenomenon or so).
Everything I came up would have a basically symmetric behaviour around midday so can't explain this.
The only asymmetry I can see is that " morning is light through a night chilled atmosphere", while "afternoon is light going around in an already warmed up atmosphere". However "this explanation" - as a ground where to plug optical phenomena of refraction or Mie scattering - would require about the same temperatures of the air, in summer as in winter, or day after day.
Another possible asymmetry is due to our long scale adaptation to luminosity or brightness, but the change I refer to is relatively abrupt around noon.
A possibility might be related to temperature of the atmosphere perhaps via refraction between layers of it..... it is the last idea that came to my mind. In this case same layering might occur independent of seasons.
Please note that I am not asking for Rayleigh scattering alone and why yellow and red are dominant near horizon at sunrise or sunset.
I am asking why the light of a clear day is not symmetrically changing centered at noon.
Please also note that before telling me that the difference I am asking about does not exist, ask yourself if you feel able to tell if it is morning or afternoon without knowing anything else but looking at the environmental light in a clear day.