Like the title says: when you see “heat rising” (the wavy/blurry area above a heat source), what are you actually seeing?
Bonus question: How does that cast a shadow? I noticed when I was opening my air fryer, I could see the shadow of the heat rising but, looking at the hot basket itself, couldn’t see it.
Warmer air has a different density to colder air, so the light refracts/bends, like through a prism.
The shadows occur as the light happens to have been focused away from those points.
Edit: Not a scientist. Currently high.
Ah, so it’s air density. I was suspecting it was water vapor.
TIL thanks!