While trying to deduce the answer to a physics-related (and safety-related) question, I ran across an apparent paradox. I am trying to figure out how quickly the hot gases rising off of a fire cool down. From what I had heard from atmospheric science: 1. Air is a lousy conductor of heat. 2. Air parcels that are of different temperatures will not want to mix. They will want to stay separate. Applying these rules would mean that the exhaust gases rising up from a fire would remain quite hot for some time. However, that does not seem to be in agreement with the observations that I had made of the temperature changes that occur as hot exhaust gases rise up from a small sized fire (in an 8 in x 8 in fire pit). The exhaust gases cool down within seconds, and there is no risk of receiving any burns if you were to place your hand a foot above the nearest flame (but it is still quite warm here). And at a distance of four feet above the fire, the exhaust gases are practically at ambient air temperature. It looks like there is something that I had missed with my knowledge of physics here. Can anyone resolve this apparent paradox?