RADAR stands for RAdio Detecting And Ranging and as indicated by the name, it is based on the use of radio waves. Radars send out electromagnetic waves similar to wireless computer networks and mobile phones. The signals are sent out as short pulses which may be reflected by objects in their path, in part reflecting back to the radar. When these pulses intercept precipitation, part of the energy is scattered back to the radar. This concept is similar to hearing an echo. For example, when you shout into a well, the sound waves of your shout reflect off the water and back up to you. In that same way, the pulse reflects off precipitation and sends a signal back to the radar. From this information the radar is able to tell where the precipitation is occurring and how much precipitation exists.