You can find this exercise on page 187 of the book Synergistic Golf.
Exercise Type: HEAVY BALL
Exercise Category: CHEST, POWER PRODUCTION, RHYTHM - TIMING, SHOULDERS, STRENGTH
Stand in slightly staggered stance (one foot more forward than the other) holding ball into chest. Look up throwing ball as far and as straight as possible overhead. Ball should return back to hands. Absorb shock of ball lowering it back to chest and explode ball back into sky again. Repeat up throws 20-30 repetitions. As accuracy improves, so will height.