eli5: when it’s hot why does it look like there’s water on the roads and why does it make a rippling effect.
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When light travels through objects of different densities, it gets bent/deflected, so to say. This is called refraction. [Here’s](https://static.sciencelearn.org.nz/images/images/000/000/049/full/Refraction-of-light-in-water20150805-30610-expmepedited.png?1625098472) an image of it. Light can also be reflected and/or absorbed, but we only need to focus on refraction for this.
Refraction can happen between pockets of air at different densities. Hot air is less dense than cold air (hence why hot air rises). Sunlight heats the road up (via radiation) and then the road heats the nearby air (via conduction). This new hot air rises and mixes with the colder air above it. Light refracts through these pockets and enters your eye. Your brain thinks that this light is coming from directly in front of you, but that light actually came from somewhere else and is just refracted toward you, and your brain processes it as this optical illusion that we call a mirage.
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