Thinking Physics Question 7

The smoke moves up as long as the air carrying the smoke is warmer that the surrounding air. As it stops a bit up this means the temperature of the surounding air is warmer at that height.
If I remember correctly it has a fancy name like "Inversion".
edit: http://en.wikipedia.org/wiki/Temperature_inversion
edit2: Forgot the letter. b) warmer

Indeed. I had an interesting story about that... a professor of physics who specialized in music (acoustician) lived a little over a mile from the campus he worked at. His neighbors were used to him listening to loud music.

On day they call him and tell him to turn down his music. He was wondering wth it could have been since his music was off... but then he realized there had been an evening temperature inversion, and the sound waves from a concert on campus were being directed back down towards the ground, and arrived at his community with high intensity.

Well the obvious answer is that the temperature above is cooler, since air thins at higher altitude. Most climbers know this.

However heat usually rises... but the smoke from your campfire did not. That implies that the air above is warmer than the air below.

Some strange thermal currents must be creating warm air at higher temperature, so in this special case my answer has to be b) warmer.

I mean everybody who's gone hiking knows that it's colder high up in the mountains than it is at the base, but I don't see what what that has to do with the smoke?

I think warmer, since if it's colder it'll make sense for the smoke to continue to rise above that level as well because the smoke would still be at lower density. instead of going flat

The smoke from the fire moves upwards as long as the air near the smoke is warmer then the surrounding air. Which mean's the air is warmer at a specific height which is generally going to be somewhere higher.
Therefore it's B) Warmer.