In hot summer, on the flat asphalt road, you will see that the ground at a certain distance is particularly bright, as if it were a piece of water.

This is a reflection phenomenon (including total reflection and diffuse reflection). I also noticed this phenomenon and looked up some information.

The reason is simple: basically anything will reflect. In hot summer, when we look at the road from the front, we will find that the road looks like a mirror in the distance. This is because the asphalt pavement will melt because of the hot weather, making the pavement smoother. At this time, because our sight is almost parallel to the road, more light enters our eyes and looks like a mirror from a distance. When the line of sight approaches from a distance, the angle between our line of sight and the ground will become larger. Because the surface of expressway is rough, diffuse reflection will occur, and only a very small amount of light will enter our eyes. So what you see is not like a mirror.