Final answer:
The height from the center line to the peak or trough is called the amplitude of a wave, which is half the peak-to-trough height.
Step-by-step explanation:
The height from the center line to the peak or to the trough of a wave corresponds to the amplitude of the wave. This measurement of amplitude represents the maximum displacement of the wave's medium from its rest (equilibrium) position. In a symmetrical wave, the amplitude is the same distance above the equilibrium position to the crest as it is below to the trough. This means the amplitude is effectively half the peak-to-trough height. For a water wave with an amplitude of 0.2 meters, a bird sitting on the water's surface would move up and down a total distance of 0.4 meters (twice the amplitude) with each wave cycle.