system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What allows heat to cast a shadow?

I stepped out into my garage and next to our heater, and I had the light on, and was looking at the wall and noticed the shadow being cast was barely visible, but it was there, and it was from the heat coming out. So, I'm just curious what of that is allowing it to cast a shadow.
gpt
Light is bent or refracted by whatever it passes through. In a room of uniform temperature, the light is bent the same way everywhere so you see a uniform image. Heat causes turbulence in the air so the light is bent in a more chaotic manner. You're seeing this as a wavy image in the shadow. This is also what causes mirages and the wavy pattern that one can see on top of a car hood when the engine is hot. This happens not only to light, but any part of the electromagnetic spectrum. Radio signals are disrupted in the morning and the evening, thermal inversion. As the air quickly heats up or cools down, the radio waves are distorted by the same effect. Thus causing a distorted signal and static in the radio program you're listening to at those times.