The color becomes yellow to red due to scattering of the shorter wavelengths. The Sun also  becomes deformed i.e. flattened and "laminated" due to refraction. The latter effect is the result when light passes through atmosphere layers with different density each refracted in their own way thus leading to wide and less wide horizontal peaces ("laminated" effect) in the Sun disk. This kind of deformation is affined with mirages.  

The picture shows the "laminated" form of a red sunset and the upper part even seems detached from the Sun disk. The lower darker part was traveling through hazy layers.