Question

why the sun appears redish the time of sunrise and redish

Answer 1

because during sunrise sun is near the equator so the blue colour of shorter wavelength disappears completely and red colour of larger wavelength reaches our eyes

Answer 2

During Sunrise and sunset, the Sun will be near the horizon. At this time, the Sun will be more distant from the Earth.

Due to this, the light will lower wavelength (blue) will get scattered away by fine particles.

And the light with the higher wavelength (red) will reach our eyes. Hence, The Sun appears reddish at the time of sunrise and sunset.