How the radar works
Weather radars send pulses of microwave radiation. When the pulse collides with obstacles, say raindrops, part of the energy of each pulse is dissipated back in the direction of the radar station. The horizontal distance from the station to the target is calculated simply by the amount of time elapsed from the start of the pulse to the detection of the return signal.
A weather radar should be sensitive enough equipment, because the return signal is much weaker than the transmitted signal. Typically, the transmitted peak power is usually 250,000 watts, whereas the return signal is only 0,000 000 000 000 1 - 0,000 000 01 Tue.
Since millimeter-sized raindrops usually fall 10 cm apart, microwaves can easily penetrate the precipitation zone and deliver information even from the interior and back of the precipitation zone. Microwaves are easily dispersed by raindrops and snowflakes, so the weather radar helps to see where precipitation falls and how abundant it is. Heavier rain gives stronger echoes, which are displayed in different colors.