Please — for the sake of your well-being, reputation and the U.S. healthcare system — do not throw a pot of boiling water into the wind if the wind is blowing at you. If you read this story and suddenly feel inspired, please take two seconds to think about your surroundings and about whether you really want your buddy Instagramming what you’re about to do.
As a polar vortex brought subzero temperatures to much of the Central U.S. on Wednesday, Midwesterners have once again embraced a cherished internet-era tradition of throwing boiling water in the freezing air and posting videos of the results — a spectacular white cloud — on social media. It’s the Arctic version of trying to fry eggs on car hoods during heat waves.
Provided you don’t hurt yourself or others near you (like dozens of people did last time it got this cold), the boiling water trick is nice a do-it-yourself physics experiment that can be a useful lesson about the properties of heat and water. The Times talked to a couple of physicists about what’s really happening. Advertisement
Is the water freezing midair?
“A lot of people say boiling water freezes immediately, but that’s not what’s happening,” said Jeff Terry, a professor of physics at the Illinois Institute of Technology in Chicago. “It’s not an instantaneous freezing of the water.”
In a video he tweeted Wednesday, Terry threw a pot of boiling water into minus-14 degree air, creating a big white cloud that drifted away, with dozens of small contrails streaking toward the ground.
The big cloud is condensate, or water that has quickly condensed into tiny droplets, which is the same reason you can see your breath when it’s cold outside. The smaller streaks are from condensate coming off falling water droplets — not water that has frozen midair.
The air is not quite cold enough to freeze water immediately, which happens at about minus-42 degrees, Terry said.
“It’s not snowing down,” he said. “You don’t see ice crystals falling to the ground. … Theoretically, if it were colder, you could actually see that.”
Does it really matter if the water is hot? Minus-14 degrees is pretty cold.
“Boiling water or hot water evaporates much, much more rapidly than cold water,” said Jonathan I. Katz, a professor of physics at Washington University in St. Louis. The amount of vapor “increases very rapidly as the temperature goes up.” Advertisement
For that reason, throwing boiling water into the air will look more impressive than throwing room-temperature water. More of it will evaporate, making a bigger cloud.
Nor do you get the same effect when it’s warm outside. Cold air can’t hold as much moisture as warm air.
Boiling Water Freezing in Mid Air (Slow Motion)
FAQ
How cold does it have to be to freeze water before it hits the ground?
What is a liquid water that freezes before it hits the ground?
At what depth does water stop freezing?
At what temperature will spit freeze before it hits the ground?
Can cold air freeze water?
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,” Nat Geo reports. Some people have even started getting creative with the experiment. “Boiling water. SuperSoaker. Oven mitts.
Why does a pond not freeze?
In still water, such as lakes and ponds, the top of the water freezes first, and since ice is less dense that liquid water, it remains on the surface and insulates the rest of the water from the cold. The rest of the pond doesn’t freeze because the temperature of the ground below never reaches freezing.
Can boiling water freeze?
Now this is a real cold weather science experiment. At -14 F/-26C, boiling water quickly condenses into a cloud of microdroplets. These can freeze due to large surface to volume ratio. Never throw hot water towards anyone. Being hit by boiling water is unpleasant. pic.twitter.com/g0Da0yU1qw
What causes a waterfall to freeze?
Also, the motion of the water can cause heating. For example, water in a waterfall gains kinetic energy as it falls, which is converted into heat and sound energy at the bottom. Therefore, the surrounding air temperature would have to be lower to force the water in the waterfall to cool to 32°F and freeze.