Rain on the Window Screensaver
The Rain on the Window screensaver shows a calm ambient scene of raindrops sliding down glass, pooling and streaking. It is free, runs in your browser, and ESC exits.
Live preview
Press ESC to leave fullscreen. Settings are saved in your browser only.
How the Rain on the Window screensaver works
The saver simulates individual raindrops that appear, grow, and slide down an invisible pane of glass.
Droplets merge with others in their path, growing heavier and accelerating, just like real rain on a window.
A soft blurred backdrop glow sits behind the glass for a cozy, rainy-day mood.
The simulation runs indefinitely with new drops continuously appearing.
The physics of a raindrop on glass
A drop sitting on a window does not slide the moment it lands, and that hesitation is physics. Surface tension pulls the water into a rounded bead, and the contact line where water meets glass catches on tiny surface defects, so a static drop can hold a range of contact angles between a receding and an advancing value. This contact-angle hysteresis acts like friction against gravity.
A drop starts to run only when it is heavy enough for gravity to beat that grip. MIT course notes on interfacial phenomena describe window drops growing by accretion until their Bond number, the ratio of gravity to surface tension, exceeds about one, and then rolling downward. That is why small beads sit still while large ones run.
How a drop behaves also depends on the surface and the liquid: well-wetting surfaces leave a trail behind a moving drop, which can break into small droplets that stay pinned, while poorly wetting ones leave none. Dirt, coatings and cleanliness change the grip, so the same rain looks different on different panes. A calm rain scene like this one is an artistic simplification of that behaviour.
A worked example
A small drop drifts down slowly until it merges with a larger one below, then together they streak faster toward the bottom of the screen.
Settings & tips
- Accent recolours the ambient backdrop glow.
- Great as a calming background for focus or sleep.
- Droplets merge realistically as they collide.
Frequently asked questions
- Is this real weather data?
- No — it is a generative ambient simulation, not tied to any real forecast.
- Is a key needed?
- No — it is a pure visual simulation.
- Is it free?
- Yes — free, no download, in your browser.
- Does it ever stop raining?
- No — new drops continuously appear for a never-ending calm scene.
- Why do small drops stay still on a window?
- Surface tension holds a small drop as a bead, and its contact line is pinned by tiny surface defects. Gravity only overcomes that grip once the drop has grown heavy enough, which is why large drops run and small ones wait.
- Why do drops leave a trail?
- On surfaces that water wets well, a moving drop leaves a thin film behind it, which can break up into small droplets that stay pinned. On surfaces that water wets poorly, drops leave no trail.
- Does the type of glass matter?
- Yes. Contact-angle hysteresis depends on the surface, so cleanliness and coatings change how strongly water clings and how easily drops start to run.