The real situation involving friction and other forces is somewhat more complicated. Force resisting motion through a medium depends on surface and shape of an object.
V is the flow velocity or relative velocity of the medium with respect to the object.
Terminal Velocity occurs when the gravitational force driving the motion is exactly balanced by drag force opposing the motion. As the skier's velocity increases, the drag force will increase. This acceleration will continue until the drag force exactly balances the gravitational force. At that point the skier will be in equilibrium and will no longer accelerate. Thus as velocity increases pressure decreases or as velocity decreases pressure increases.