You might think we know all there is to know about raindrops, including how they form on windshields and windowpanes. But the physics of this process has long been a mystery. Now, a new study shows just how it happens, contradicting expectations of what a proper liquid should do. Most scientists assumed that the process of drop creation from a film would be a perfect reversal of what happens when drops spread out. These spreading droplets typically maintain a smooth, rounded shape—basically a series of ever wider drops—while they melt into a film. To find out what actually happens when that film fattens up into a drop, scientists designed a system that used electrodes to force a single droplet into a film. When they removed the electric field, the film reverted into a droplet, a process the scientists captured using high-speed imaging (above). Their finding? Liquid films that coalesce into drops first form a raised rim around their edges, looking a little bit like the stage at a one-ring circus, the researchers report today in Science Advances. This could mean an entirely new way of designing products that make use of thin-liquid films, like smartphone screens and self-cleaning paint; a better understanding should help manufacturers control the behavior of liquids.