How does boiling water turn into snow when thrown in cold air?

Throwing boiling water atomises it into a fine mist of tiny droplets with a huge combined surface area. The hot droplets evaporate almost instantly, and the fresh vapour immediately super-saturates the surrounding very cold air, which can hold almost no moisture. The vapour condenses and freezes into microscopic ice crystals, producing a white snow-like cloud.

What temperature does boiling water turn to snow?

You generally need air temperatures of about -25°C (-13°F) or colder for the effect to look impressive. The colder the air, the more dramatic the cloud. Around -10°C the trick simply doesn't work — the warm vapour can spread out into the air without having to condense and freeze.

Does boiling water actually turn into snow?

Not exactly real snowflakes. The white puff is a mix of water vapour, tiny condensed micro-droplets and microscopic flash-frozen ice crystals — closer to ice fog than the six-armed crystals that fall from clouds. It's technically frozen water, but its structure is much simpler than that of natural snow.

Why won't cold water do the same thing?

Cold water has a much lower vapour pressure and doesn't atomise or evaporate readily, so when you throw it into freezing air it just falls to the ground in droplets. Boiling water is right at the edge of becoming a gas; the small jolt of being airborne is enough to push much of it across that threshold all at once.

Is the boiling-water-to-snow trick the Mpemba effect?

No. The Mpemba effect is a separate (and still debated) observation that hot water can sometimes freeze faster than cold water under certain conditions. The boiling-water-to-snow trick is about atomisation, evaporation and rapid re-condensation in cold air, not about hot water freezing more quickly than cold.

How Does Boiling Water Turn Into Snow When It's Too Cold Outside?

Table of Contents (click to expand)

The Conditions
Why Does Boiling Water Turn Into Snow?

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When it’s freezing cold outside and you throw a cup of boiling water into the air, the water droplets rapidly evaporate into vapor that immediately condenses into a cloud. The cloud looks like snow, but it’s actually just water vapor.

It’s freezing cold outside and you decide to take a cup of boiling water outside and throw it into the air. Instead of falling to the ground and searing a hole in the already-fallen snow… Boom! It magically turns into snow!

Have you ever seen this happen before? In recent years, this has become all the rage to videotape, particularly in regions that aren’t used to such extreme temperatures.

These videos go viral every winter when some bored soul sitting in the confines of a heated room gets the crazy idea of recording this bizarre experiment and sharing it on social media.

However, have you every wondered why water at its boiling temperature can miraculously convert into snow in the blink of an eye?

Exactly… I had the same reaction. It’s pretty hard to believe.

But wait a minute! Can you do this anytime and anywhere when it’s freezing cold outside?

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What Happens When You Throw Boiling Water Into Freezing Air?

The Conditions

Not exactly. This transformation doesn’t really work that way. There are certain conditions that need to be fulfilled in order to create snow from boiling water.

Two conditions to be precise, and if they’re both present, then you should be able to create snow from boiling water:

1) Water should be boiled at 100° C (or 212° F)

2) The outside temperature should be very cold, in the range of (-20° to -30°C or below 0°F) Wow… that is awfully cold!

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When boiled water is thrown into air at such a cold temperature, it instantly turns into snow and simply drifts away.

However, be careful when trying out this cool-looking phenomenon, and don’t throw the hot water straight up or onto other people. The above phenomenon would not work if the water temperature is less than 100°C (212° F) or if the outside temperature is not cold enough (outside the range of -20° to -30°C, or below 0°F). In other words, if these conditions are not satisfied, you may end up hurting yourself or others with the boiling water.

This is such an unbelievable phenomenon, however, that people go outside in these freezing temperatures, stand in the snow, and throw water to make even more snow! What can I say! Humans can be very difficult creatures to understand.

See the video (below) of a woman having quite a good time at a temperature of -30°C.

Why Does Boiling Water Turn Into Snow?

Boiling water is closer to the point of evaporation than cold water. Cold air is very dense, which makes its capacity to hold water vapor molecules very low. Therefore, when hot water is thrown into extremely cold air, the smallest droplets are able to cool and evaporate in a dramatic cloud before they reach the ground.

In reality, the white cloud isn’t made of true, six-armed snowflakes. It’s a mix of water vapour, condensed micro-droplets and tiny flash-frozen ice crystals — closer to ice fog than to falling snow. Whatever you call it, it still looks like a magic puff of snow, which is why these clips go viral every winter.

As it turns out, sub-zero temperatures aren’t all bad. You can’t make “real” snow this way (the trick won’t work with cold water, by the way — cold water doesn’t atomise or evaporate fast enough to drive the cloud), but a giant puff of ice fog from a kettle looks pretty cool. (And no, this isn’t the Mpemba effect — that’s a separate, still-debated claim that hot water freezes faster than cold water under certain conditions.)

Just remember to be careful! Don’t burn yourself or anyone else while trying to make the next viral video!

References (click to expand)