HEAT RISES
(My second favourite hate)
You can even see the heat rising above a fire..it is all wiggly. We know heat rises because it is always hotter at the top of a room than the bottom!
WRONG!
Hot air or hot water (or generally: HOT FLUIDS) rise. This is because as a fluid heats it expands, is then less dense than the surroundings so it is pushed upwards (Archimedes upthrust). This process is called "convection".
HEAT is a form of energy (they prefer to call it "Thermal Energy" now) and energy cannot rise, it is absorbed by the fluid which rises.
As for those wiggles which you see over a flame………..
You are looking at the scene beyond the flame, but the light coming from it to your eyes passes through the hot air. When air is at a different temperature light going through it "bends" or refracts….so the light coming to your eye keeps getting refracted back and forth in the different temperatures of the hot air.