What is Doppler radar, which the TV weather people use to look for storms?
Radar (short for Radio Detection and Ranging) uses microwaves to find an object. The idea is pretty simple: You send out a pulse of microwaves and wait for an echo that corresponds to some having been reflected back. Knowing the speed of the microwaves (which is the speed of light) you can tell from the delay how far away the object that reflected them is. If there are multiple objects, you get multiple echoes, and in this way you can find objects in any direction, and their distance.
