The physics of the jump serve is simple, as the ball rotates with top spin, it drags more air which must move faster than the air on top to get by in the same amount of time. The physics of the float serve guarantees you can’t know where the ball is going. A non-rotating ball is subject to unpredictable interactions between drag, lift and drag crisis. Air moving past a sphere travels in laminar flow at the speed of moving air increases from zero. At very low speeds, the air that touches the ball doesn’t move at all. Eventually there comes a speed where the boundary layers are no longer able to hold together and break away called “turbulent flow”.
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