Radar and ultrasonic sound waves made by dolphins Even though dolphins live in the darkness of the sea, they can still search for food in the form of fish.

They do this by emitting sound that cannot be detected by the human ear (ultrasonic sound waves) and catching the sound that comes back like an echo. Even though they cannot see their food, they can tell their direction and distance by using ultrasonic sound waves.
The way radar works and the way that dolphins use ultrasonic sound waves are much the same.
Radars used at airports emit radio waves from an antenna and catch the radio waves that are reflected off aircraft.
Through this, the direction and distance of aircraft can be detected.