Frozen Soap Bubbles: ZALUSKArt’s −15 °C Film and the Snow-Globe Effect

A clear soap bubble rests on fresh snow. Within seconds, feathery ice crystals appear on its skin, swirl around the sphere and knit together until the whole bubble looks engraved with frost. ZALUSKArt’s short film Frozen Soap Bubbles captures that transformation in close-up, filmed at about −15 °C.

The film was published on Vimeo in January 2016 and quickly spread around the world. Here is the story behind it, and the physics of what you are watching.

Watch Frozen Soap Bubbles on the creator’s Vimeo page.

The story behind Frozen Soap Bubbles

The film began with a small family argument. The filmmaker’s three-year-old daughter did not want to put on her jacket, even though it was bitterly cold outside. He told her it was so cold that even soap bubbles freeze, and that it looks beautiful. She was delighted by the idea, so he promised to film it for her.

The shoot was harder than it looks. At −15 °C, only about 5 to 10 per cent of the bubbles survived long enough to freeze; the rest burst almost instantly. The bubbles that made it into the film are the lucky few. According to the filmmaker, his daughter now thinks winter is magic.

How soap bubbles freeze: the snow-globe effect

A soap bubble is air wrapped in a very thin liquid film. In 2019, a team led by Jonathan Boreyko at Virginia Tech published a study in Nature Communications called “How soap bubbles freeze”, filming bubbles in a walk-in freezer at about −18 °C.

They found that freezing starts where the bubble touches the cold surface and climbs upwards. As water turns to ice it releases heat, and that warmth changes the surface tension of the film. The difference drives a flow, known as a Marangoni flow, that tears tiny ice crystals loose and carries them up and around the bubble. The crystals grow as they drift, so the bubble freezes from many points at once. The researchers named it the snow-globe effect, and it is exactly what you see in ZALUSKArt’s film.

Why bubbles freeze differently in warm air

The same team also tested bubbles on a chilled surface between −10 °C and −40 °C in a room at about 25 °C. This time the freezing front crept slowly up from the bottom and then stopped partway, because heat moves poorly along the thin frozen film. The top stayed liquid.

Frozen bubbles do not last long either way. After a few minutes they slowly deflate, as the air inside escapes through tiny pores in the ice, roughly 10 to 100 micrometres across. The soap solution used in the study froze at about −6.5 °C, well below the freezing point of pure water, which is why bubble art needs a properly cold day.

Tips for photographing frozen bubbles

Choose a calm, very cold day: wind pops bubbles and blows the crystals off course. Blow the bubble gently onto snow or a cold surface, and set your camera up close before you start, because the crystals form within seconds. A dark background, as in the film, makes the pale ice branches stand out, and low morning or evening light adds a warm glow.

For more of the same creator’s work, see the Warsaw frozen-bubble gallery. Compare it with Chris Ratzlaff’s frozen bubbles in Calgary, or see what happens to frozen flowers.

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