I have noticed that sometimes on a hot day, while travelling, I will see a water puddle on the road a little far away but when the car reaches there, there is no puddle or water.
I tried searching about this but couldn’t really understand why light changes its direction and we perceive it as a virtual image which looks like water.
I would really like to understand why this really happens.
Thanks!
In: 2
So, there’s an effect in physics where light doesn’t always travel in a straight line. When moving between different materials, like from air into water, light bends. [Makes some potentially funny pictures](https://aplusphysics.com/community/index.php?/blogs/entry/29959-guy-in-a-pool/).
Now… hot air and cool air sorta count as different “materials” here, and as the temperature of the air changes a lot, light will actually curve a bit as it approaches the hot air. On a hot day the black-ish road really soaks up sunlight, gets hot, makes the air hot, and light will start to bend over reasonably long distances. It’s not water – you’re seeing the sky on the hot road. And calling it a “reflection” isn’t really fair since there was no bouncing of light, it curved away from the ground.
This is also what makes heat lines that you can see. Hot air isn’t directly visible, but if you ever opened your car door and it was really hot in the car, and you can see the heat radiating out of it, that’s the same effect at a much smaller scale.
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