Put the ball in the upright air-flow (flowing upwards) and observe its behaviour!
The ball at a certain height stops and floats. Which force does overcome gravity in this case?
The force of gravity directed downwards is compensated by the pushing force of the air flowing upwards in the point in which the force of gravity and the pushing force compensate each other.
Perhaps an even more interesting question is why is the ball dancing? Why does not it fall down?
The answer is Bernoulli's principle: within a flowing fluid pressure decreases, while the more the speed of the fluid increases the more the pressure decreases. This is why within the air fluid which is flowing with great speed the pressure is smaller than the pressure in the air that is not moving, surrounding the air-flow. So, if the ball put into the middle of the airflow moves to the side. This difference in pressure pushes back the ball into the middle of the air-flow.
Bernoulli's principle is proved by damage done by hurricanes: the wind tears off first the roof of the houses (better to say it lifts them up), because the pressure of the air above the roof flowing with great speed diminishes drastically, so the pressure within the house "pushes up" the roof.
