Question

Where are waves found in nature?

Answer 1

A wave is a disturbance that propagates through a medium. So, it is everywhere.

Explanation:

A wave is a disturbance that propagates through a medium.

A broad characteristic classification:

Mechanical

Elecromagnetic (including light)

(Yet to be confirmed) Gravitational

Matter

For more details on types (transverse, longitudinal and surface waves), sub-classifications and examples:

Physics.info/waves/summary.shtml