Why does rainwater pool into a shape of windshield wipers?

Question

I’m sitting in my car, it’s raining and wipers are off. However, I can clearly see how the droplets pool in a specific manner, reminiscent of wiper movements. Can someone explain the physics behind it?
Here’s how it looks like: https://ibb.co/C5M7YCL

In: Physics

Answer 1

Smooth glass and dirty glass grip water differently. The wipers keep the glass (relatively) clean.

A car that is washed frequently will see much less of this effect.