Why can you see the heat coming off the ground on a hot day?
In: Other
people think of air as invisible, but it’s really more see-through than invisible. just like clear glass, air shows what’s behind it, but can distort that image due to all sorts of factors.
in the case of visible heat, the factor is **density**. hot air is less dense, and cool air is more dense, but the level of density isn’t always uniform, since hot air rises and heat dissipates as it moves away from its source. in cases of extreme differences in temperature (ie air directly above hot asphalt), you wind up with a large difference in that air density. this functions a bit like a lens made of glass, where the change in thickness can bend or magnify our image of what’s behind it. the waviness of the image is due to the fact that the air is moving, normally upwards to dissipate heat away from the ground.
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