Here’s How Boiling Water Can Turn Into Ice

It's so cold in parts of the United States that a cup of boiling water tossed into the air can crystalize into ice and snow before it hits the ground.

Videos of such strikingly weird phenomena in Minnesota, Vermont, New Jersey, and elsewhere are making the rounds as subzero temperatures, high winds, and snow blasts across the country.

Thanks to a series of weather patterns, including a notorious bomb cyclone, Florida's capital got its first snowfall in three decades Much of New England, meanwhile, is bracing for a snowy hit from the bomb cyclone (also known as bombogenesis). (Related: "U.S. Cold Snap: What Do Bitter Temperatures Do to the Human Body?")

Here's the science behind viral cold-weather videos:

Boiling Water Turns to Snow

"Water is a special substance," says Taneil Uttal, an arctic climatologist for the National Oceanic and Atmospheric Administration (NOAA), because it can exist as a liquid, a gas and a solid at the same time.

This is known as the triple point, and temperatures need to reach 0.01°C (32.018°F) for it to happen, Uttal explains.

When you boil water, you're adding energy to water in its liquid state. That energy moves the molecules farther away from each other until the water vaporizes into a gaseous state.

"When you throw [boiling water] into the air, the hot water forms into hot droplets," says Uttal.

Because they're so hot, those tiny water droplets start to vaporize. But since cold air can't hold as much water vapor as warmer air, the water condenses. Extremely cold temperatures quickly freeze the water droplets, which fall as ice crystals.

This explanation also applies to a 2014 viral video of a man in Ontario shooting steam from a water gun outside at -41°C (-41.8°F). The hot water in the water gun hits the cold air and instantly condenses into ice crystals.

Frozen Clouds Over Lakes

During typical U.S. winters, the air is warm enough over many major lakes that when water evaporates, you can't view the droplets without a microscope. But in extremely cold temperatures, water vapor freezes instantly and creates ice fog.

"In the Arctic, we call this riming," says Uttal, whose research often takes her to the Arctic. "We get rime all over our instruments from the ice fogs."

According to Uttal, temperatures can dip so low that riming can even freeze your eyelashes together. "It's actually why I haven't bought a pair of metal [framed] glasses in a few years. I buy plastic ones to keep the rime from freezing the frames to my face."

Frozen Soap Bubbles

Soap bubbles form when a layer of water molecules gets trapped between two layers of soap molecules. When it's cold outside, the water layer freezes before the soap bubble pops.

After the water layer has solidified, the air inside the bubble will start to spread out. According to Bryan Wunar, director of community initiatives at the Center for the Advancement of Science Education at the Museum of Science and Industry, Chicago, the colder it is outside, the longer the bubble will retain its shape.

"The air inside the bubble will diffuse faster if it's warmer and slower if it's colder," says Wunar. "If it's very cold out, such as the negative temperatures we've seen this week, the bubbles can form ice crystals. Instead of popping, [the bubbles] crack after forming into a crystalline structure."

According to Wunar, you can sometimes see the air diffusing through the semi-rigid soapy structure.

"A very similar process happens with balloons and car tires," he says.

A balloon in subzero temperatures deflates because the cold slows down the air molecules inside the semi-rigid structure, Wunar explains. "When you bring the balloon back into room temperature, it will slowly inflate again."

He warns that many people are inflating their tires without realizing the tire pressure will increase again once the weather improves: "This is a common mistake. People don't realize they're actually over-inflating their tires."

Wunar says the viral videos are good for the science community: "It's exciting that we can use [the cold weather] to encourage people to think critically about the world around them."

This story draws from interviews conducted in January 2014.

A man pushes his way through a winter snowstorm in Atlantic City, New Jersey , on January 4, 2018.
A man pushes his way through a winter snowstorm in Atlantic City, New Jersey , on January 4, 2018.
Photograph by Matt Rourke, AP

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