Why does the asphalt road look like it has a layer of water in the summer?

On hot summer days, when driving or riding a motorcycle, you often see the road surface in the distance shimmering, as if a layer of water has accumulated. But when you actually get close, the ground is dry and there's nothing there. This phenomenon is called a 'mirage,' a visual effect caused by the refraction of light. The asphalt road in the summer absorbs a lot of heat, making the air near the ground hotter than the air above it. Air at different temperatures has different abilities to refract light, so as light passes through these air layers, its direction gradually changes. When light from the distant sky passes through these air layers and enters your eyes, it can make you mistakenly believe that there is a water surface on the ground. Furthermore, this illusion changes with the viewing angle, so the closer you get to the area that appears to have accumulated water, the more it seems to move further away. This is why you often see 'puddles' on hot highways that you can never get close to. Sometimes, what your eyes see is not necessarily the true appearance of things, but a trick of the light playing out in nature.