When air resistance is taken into account, the time during which the ball rises would be longer than the time during which it falls. Air resistance acts to slow down the upward motion of the ball, therefore it takes longer to reach its highest point. Conversely air resistance also acts to speed up the downward motion of the ball, causing it to fall faster than it would in a vacuum. As a result, the time taken for the ball to rise against air resistance is longer than the time taken for it to fall.