Stillness is misleading here. A balloon that looks frozen above a field is locked in a tight negotiation between gravity and buoyant force, not held up by any passing gust. Heated air inside the envelope has lower density than the cooler ambient air; by Archimedes principle, the surrounding atmosphere pushes upward with a force equal to the weight of the displaced cooler air, and that upward push can match the total weight of fabric, basket, burner and passengers.
The real surprise is that the air does not need to move sideways at all. Air pressure acts in every direction, and because pressure decreases with altitude, the net effect on a light, swollen envelope is an upward resultant that engineers simply call lift. When the pilot throttles the burner, temperature and density inside shift, altering that lift so slightly that the balloon may rise a little, sink a little, or settle into a level where buoyant force and gravitational force cancel like balanced entries in a ledger.
Wind only carries the whole system along. It does not supply lift. What keeps the balloon hanging is this invisible pressure gradient of the atmosphere, a standing background field that turns hot air into a temporary flotation device and turns the sky, column by column, into something very close to a sea.
