Birthday balloon

B received a helium balloon for his birthday from Toys R Us. The balloon has lost a lot of its helium, and drifts near the floor until it comes near the heater. When it reaches the heater, it is caught in the upward flow of heat coming from the heater, rises to the peak of the ceiling then drifts down again. It is interesting to watch, sort of like unseen hands are moving it around. :D