Raindrops hitting the side windows of a car in motion often leave diagonal streaks even if there is no wind. Why? Is the explanation the same or different for diagonal streaks on the windshield?

An object's acceleration is the rate at which it speeds up or slows down. This implies that the velocity is changing automatically. the term"constant acceleration" simply mean that the velocity varies by the same amount with each passing unit of time.

The automobile drives horizontally in relation to the ground, but the raindrops fall vertically in relation to the ground. Both the automobile and the raindrops' velocities are related to the moving car, which has both vertical and horizontal components. The droplets' velocity relative to the moving automobile differs from the raindrops' velocity related to a stationary observer. That's why raindrops produce diagonal streaks on the windshield, and these diagonal streaks on the glass are caused by something else entirely. Raindrops are forced off to one side of the windshield due to air resistance.

Hence, the explanation is the same for different diagonal streaks on the windshield.