Throw two pebbles into a pond so that they hit the water a few feet apart. Observe the radiating waves. Watch when the two wave systems intersect and what happens to the wave amplitude as the waves...

Throw two pebbles into a pond so that they hit the water a few feet apart. Observe the radiating waves. Watch when the two wave systems intersect and what happens to the wave amplitude as the waves spread.

The next time you come near a pond, observe the wave systems created by water fowl moving on the water surface.