They kinda look like water paddles and if you come closer, they vanish. Looks like this:
https://miro.medium.com/proxy/1*8x5qar5YhqLh7SLMrCVcXw.png
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Light bends when it travels through a medium (e.g., air or water) that change in its “refractive index” which basically just means “the amount light bends.”
The refractive index changes within the same medium (air) because of temperature. So the air next to a very hot surface like a road is literally bending. You’re seeing the weird, scattered reflection of the sky. It’s hazy because hot and cool air mix chaotically.
It’s called a mirage. It’s essentially what happens in deserts too, where people can be tricked into thinking there’s water some distance away, but there really isn’t any water there.
Hot air is much lighter and less dense than cool air, so normally, hot air rises up, and cool air sinks down. It’s like when filling a bath, if you put cold water in first, and then hot water, and jump in without mixing the water, the lower layers of water will be much colder than the surface, because the hot water has states at the top since it’s lighter. Air works in a similar way.
However, on very hot days, black asphalt (and sand in deserts) absorbs a lot of heat, and this heat can warm up the air right next to it, just above the surface of the ground. The air gets heated up much faster than it can rise away and be replaced by cold air, so it ends up trapped near the surface.
Since hot air is less dense, it also refracts light differently than cooler air. When a layer of hot air is trapped near the ground, and we see it from a good distance away, the light that shines on the ground is refracted by the layer of the hot air layer in a way that makes it look like it’s reflected towards us. It’s not actually reflected to us, but it bends weirdly, and that makes it look like a reflection of light. Since the hot air is swirling around (it is air, after all, and doesn’t stay still), the refracted light also shimmers around a bit. All this information tricks the mind into thinking that there is water or oil on the ground, since water and oil also reflect water in a similar way, and shimmer.
This gets asked a lot. Please search before posting.
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