This is mainly related to the aerodynamics of the car. Generally, the rear window is equipped with a hatchback sedan or SUV. The trunk of this type of car does not protrude. When the air flows through the body, a negative air pressure is formed . This negative pressure will cause dust to rise and stick to the rear window glass and the trunk door.
At this time, the sight of the rear window will deteriorate. In order to improve such a phenomenon, a wiper is usually installed on the parking glass, and a sprinkler is also installed together. If the sight of the window is blocked by dust after opening for a period of time, By pressing the operation lever of the water spray wiper in the opposite direction, and letting the rear window glass spray water and activating the wiper, the dust can be removed and the rear window sight can be restored.