Adverse yaw refers to the tendency of an aircraft to yaw in the opposite direction of a turn. When a pilot initiates a turn, the aileron on the wing that is rising (the wing on the outside of the turn) moves down, increasing lift and drag on that wing. Simultaneously, the aileron on the wing that is descending (the wing on the inside of the turn) moves up, decreasing lift and drag. The increased drag on the outside wing causes the aircraft to yaw away from the direction of the turn.
Therefore, during a turn, the primary effect of adverse yaw is the tendency for the aircraft to move in the direction opposite to the intended turn, which is why it is described as affecting the direction of yaw opposite to the turn itself. This understanding is crucial for pilots as they need to counteract adverse yaw with coordinated use of the rudder to maintain a smooth and efficient turn.
The other options describe scenarios that do not pertain to the nature of adverse yaw. Maintaining altitude can be a separate issue influenced by other factors such as bank angle, but it is not directly about yaw. An uncontrollable climb is more related to inadequate power management or incorrect pitch attitudes rather than a direct consequence