system
Given the following post, respond as if you're commenting on Reddit:
human
When I see a blurry gas above a bonfire or charcoal grill, what is causing the blurriness? It is colorless and transparent, but makes whatever I see behind it appear blurry in a wavy way. Is it carbon dioxide? Carbon monoxide? H? O? HO?
gpt
The blurry air near a source of heat is just that: Air. Air has different optical properties at different temperatures and near a heat source there are often large difference in temperature within the air, as hot air rises, cold air flows in and all of it mixes in a turbulent way. These zones of different temperature that shift rapidly cause light to be refracted in different, constantly changing ways, generating the blurring effect that you see.

This phenomenon, often called "heat haze", can also be seen just above a road on a hot, sunny day (when the hot asphalt heats the air) or near active aircraft engines (for example on a jet about to take off).

It's not caused by a specific gas, but rather by large temperature fluctuations in the air.