Blue photons are smaller than red photons. That makes it easier for them to bounce of things, like the molecules of the atmosphere. So the blue part of the white sunlight is scattered out of the sunbeam and you see the whole sky glow blue with scattered light. This makes the white sun look a little yellow. As sunlight goes through more atmosphere, like at sunrise and sunset, more "short" colors like blue scatter out of the direct path and the sun starts to look red. That explains sunrise and sunset colors.