Detecting the shape of a raindrop with polarized waves The shape of raindrops can be determined by using a polarized wave.

Small raindrops in the atmosphere are spherical, but they become vertically compressed into an elliptical shape when they get larger.
When raindrops are small, there is no difference in the strength of the reflected vertical and horizontal polarized waves.
When the raindrops get bigger, however, the strength of the reflected horizontal polarized waves gets greater.
Through this the shape of raindrops can be determined and their size can be speculated.