What Causes Car Reflections on Hot Roads?

[chbritton]

Why is it that on a hot day, you can see a cars reflection on the road. What is this called?

 

[Dale]

It is called a mirage. IIRC, it happens because the hot air next to the ground is less dense than the cooler air above, and so light gets refracted upwards.

 

[Danger]

Those inversion layers are also responsible for a high percentage of UFO reports. The image can turn up anywhere within reason, such as a hundred feet off of the ground.