When we are driving on motorway in sunny afternoon we can observe a mirror like reflection on the road at some distance why is it so. !!?
It belongs to what are called "mirage" optical phenomena, some very spectacular.
This happens when the index of refraction changes due to the changes in density in the air. The road phenomenon is due to the heat coming up from the asphalt.
Heat haze, also called heat shimmer, refers to the inferior mirage experienced when viewing objects through a layer of heated air; for example, viewing objects across hot asphalt or through the exhaust gases produced by jet engines. When appearing on roads due to the hot asphalt, it is often referred to as a highway mirage.