eli5: How does heat bend light and make this weird effect
In: Chemistry
It’s changes in density.
There is hot air rising from the road surface that’s mixing with slightly cooler air. Hot air is less dense, so it bends light slightly differently. Thus, the shimmering effect
Light wants to maintain as much energy as possible as it passes through things. The denser the material, the more energy it could lose. So it bends. Think of it like this…
Let’s say you and your friends are kicking a ball around in a grassy field. You kick the ball and it goes sailing far away to your front right (2 o’clock on an analog clock). It sails over a big strip of mud and then lands in the parking lot. You now have to go get the ball. Are you going to go straight for it through all that mud or wouldn’t be faster to go for the ball, turn to cross the mud at the thinnest point, and then turn back to the ball? Well light behaves a similar way.
So when light hits something denser it bends to keep traveling as fast as possible. This is why the straw in your glass of water looks bent. Air can change density too. Hot air is less dense than cool air. Rock and asphalt can get much much hotter than the air as they absorb so much heat from the sun. So they start heating the air causing it to be less dense and rise. Thus the changing density of the ever moving air will cause that bending and shimmering pattern you noticed.
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