Rain is familiar, repetitive and never perfectly uniform. That combination gives the brain enough variation to notice without creating the expectation of a plot or an important event. On a screen, small changes in droplets, reflections and moving clouds soften the stillness of the display while a fixed viewpoint keeps the composition easy to leave in the background.
The sound can be equally useful. A continuous layer of rain may help cover irregular household noise, distant traffic or short interruptions that would otherwise stand out. This masking effect is one reason rain recordings are often used for sleep, reading and concentration. It is not necessary to play the audio loudly; a low, even level generally integrates better with the real room.
Rain also carries a strong sense of shelter. When the weather is visibly outside a window, the viewer reads the room on this side of the glass as protected and warm. That contrast can make a bedroom, reading corner or evening living room feel more settled, especially when the scene combines cool exterior light with lamps, books, plants, candles or a fireplace inside.
The theme is universal enough to work across different interiors. A city shower can suit a modern apartment, forest rain can support a natural room, and a lake or gothic window can create a more immersive mood. The scene does not need to imitate the viewer's actual location. It only needs stable framing, credible motion and a visual rhythm that remains comfortable over time.