"One Hundred Thousand Whys" Why weather radar can quantitatively estimate precipitation

The basic principle of general radar is that the radar first emits electromagnetic waves, which are backscattered after encountering the target object. The radar then receives this backscattered signal to measure the distance and size of the target object.

When weather radar illuminates precipitation clouds, electromagnetic waves will also be backscattered when encountering raindrops in the air. The intensity of backscattering is basically related to the size and number of raindrops, so weather radar can measure it like this The total amount of raindrops that have not yet reached the ground. "Precipitation" refers to the total amount of raindrops that eventually fall to the ground. Obviously it grows in the air and eventually falls. Therefore, it is obvious that the corresponding relationship between the weather radar observation information and ground precipitation can be established based on this to achieve quantitative estimation. The purpose of precipitation.