Question about heat waves?

Question

today i was outside and it was really hot.

when i looked at the top of a car i was able to see the heat waves on the surface, but nowhere else. i only saw the heat waves on the surfaces of cars. why?

Answer 1

The index of refraction of air changes with temperature.

What you were seeing was the effect of differing indexes of refraction bending the light.  So where you see heat waves is where the temperature changes rapidly.  If all the air were 150 F you wouldn't see any heat waves.  Where you see them is when the air changes temperature rapidly from place to place.

Answer 2

You were seeing small convective disturbances in the air immediately above the car.  That was because the surface of the car was absorbing more solar radiation than the other surfaces.  In turn, the car top became much hotter than the other surfaces, making the air immediately above the car top much hotter.  That air then rose, and as it did, you could see the small irregularities in the density of that heated air as a shimmering effect.

Answer 3

probably because the car's roof absorbed more heat making it hotter than the things around it-- i think