why sun appear to be larger during sun rise & sunset time?

 

During the sunrise and sunset the sun is at the horizon and refractive index of the atmosphere of the earth decrease with height. Due to this light reaching the earth’s atmosphere from different parts of the vertical diameter of the sun enters at different heights in earth’s atmosphere and so travels in media of different refractive indices at the same instant and hence bend unequally.

Due to this unequal bending of light from the vertical diameter, the image of the sun gets distorted and it appears oval and larger.

 

Rgds

Team Topper