Rooftop Greenhouse

What you can do here

Watch the water run downhill

Drops gather on the roof glass and run down the slope, to the left on one side of the roof and to the right on the other, until a glazing bar stops them. On the upright glass they run straight down. Each raindrop that strikes the roof shows for a moment as a bright speck and leaves a bead behind.

Let a drop fall

Touch the basin or the pipe. A drop swells at the pipe's lip for about a second, lets go, and lands in the basin with a plip and a ring. One every four seconds.

Turn the pipe up or down

Downpipe goes from a slow drip, one drop every few seconds, to a thin steady stream. The water in the basin trembles under a stream and rings under each drip.

Change the rain

Rain sets how hard the rain strikes the roof, how many drops run, and how much rain falls through the city lights outside.

Use it as your wallpaper

Press F for fullscreen and M to turn the sound off and on; the volume and your sound choice carry over to every wallpaper. The sound keeps playing if you switch to another tab.

Live link

On a computer desktop

Some wallpaper apps can show a web page behind your desktop icons. Give one the live link above and the scene runs there on its own: no page around it, no ads and no sound.

On a TV or a spare screen

Open this page and press F, or use Fullscreen. While it’s in fullscreen we ask the browser to keep the screen from going to sleep.

On a phone or tablet

Save image downloads exactly what’s on the screen as a picture. Set it as your wallpaper from your photos; the phone will crop the sides.

A live wallpaper keeps a page running all day. Through the live link the scene draws at most 30 frames a second and stops while the screen is covered, but on a laptop it still costs some battery.

Why the rings are so thin

You see the basin almost edge on, so a circle on its water looks like a long, thin ellipse: here about nine times wider than it is tall. The ripples are worked out on the water's own surface, as if seen from above, and then drawn at that angle, which is why they spread wide and flat.

About the sounds

Two recordings and one quiet layer: rain on a glass roof, a single drop into a clay basin, and the air of a quiet room. The drop's sound is timed to the drop you see: it swells at the pipe while the sound begins and lands as the plip comes.

If you’d rather just watch

• Neon Rain Alley, rain and neon in a back street
• Rainy City Night, a drawn rain screensaver