Interference of waves is one of the most important phenomena in nature.
Even two circular waves spreading outward already show quite an intricate pattern. Witness the blue stripes going diagonally across the picture (e.g. in the upper left part). These are the places where the waves cancel each other and the water surface would not move.
Here are a only a few of the many phenomena that involve interference of waves:
- Rainbow-colored appearance of thin soap or oil films or the appearance of some butterflies or insects
- Fluctuating strength of a radio signal being scattered from trees, buildings etc., depending on where you try to receive it
- Highly precise distance measurements, e.g. to detect movements of the earth