Why does the setting Sun look bigger? (Adams & Co)

Is the reason in the organ of vision of human beings? In a meaning an error of vision inevitable?
No. The bigger size of the Sun is not an error. The size of the appearance is really bigger. Not the error of vision.
In short, the redder, the bigger. You can prove it in the laboratory of every your university easily. With just the blotting of red light the Sun cannot make form. Forming lights must be running lineally into the human being's eyes.
In Japan. the white small setting sun is always seen on a cloudy day with dust from China. The number of molecules in the air relates.