Why do you feel water on the dry asphalt road when it is very hot?

This happens all the time in the desert. When the sun shines on the sand, the density of the hot air layer near the sand surface is smaller, and the refractive index is lower than that of the upper air. When the light from a distant object enters the hot air layer with low refractive index, it will be refracted, the incident angle will gradually increase, or total reflection will occur. When people look against the reflected light, they will see the reflection of distant objects, as if they were reflected from the water.