If I have a hollow cylinder in thermodynamic equilbriumin presence of gravity (like empty silo), which has higher temperature: bottom or top of the cylinder?
If it's truly and completely empty (i.e. vaccum), then it's the same temperature everywhere and thus the temperature is independent. If it's on Earth, and it's empty of solids but full of air, the top is going to be hotter than the bottom. There will be some amount of heat trapped in the silo, and convection will occur between the outside walls and the air inside. The hotter air gets less dense and rises to the top.
