During the winter we keep the basement door closed so that the cold air from upstairs won't flow into the basement. Then we heat the basement and the upstairs gets heated partially by conduction through the floor. But during the summer, the upstairs is heated while the basement (unfinished) is around 62 degrees F (16 degrees C).
How hot does it need to be upstairs before opening the basement door will actually heat the basement? I know hot air rises, but it seems that if there were a massive heat difference between upstairs and downstairs that air turbulence or diffusion would carry some of the heat. There's an 8' 7" height difference between upstairs and downstairs.