Doppler Radar

A doppler radar is a machine used by weather people such as the ones in the news. This machine sends waves that collide with other waves in the outer areas, sending waves back to inform what's going on. If the waves sent by the doppler radar send back some kind of wave, the doppler catches that information. With that information is how we predict if it's going to rain or snow.

Interference

Constructive interference is when the crest of a wave is super positioned with the crest of another wave (or trough with trough). Destructive interference is when the crest of a wave is super positioned with the trough of another wave. An example of both would be sound waves. We can tell that it's constructive interference when the sound is louder and when it's destructive the sound gets quieter.