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How to make snow in -40c

9 years 2 weeks ago

Throwing boiling water up in the air in -40c weather. Cool effect. [pun].

Some more info on NPR: [quote within quote]

http://www.npr.org/blogs/thetwo-way/2014/01/06/260188337/dont-just-shiver-here-are-3-cold-weather-experiments-to-try

"..Yep. It turned into ice crystals before it hit the ground. What's counterintuitive is if you threw a cup of ice-cold water, it would fall to the ground still a liquid. Why?

Live Science asked Mark Seeley, a climatologist at the University of Minnesota, to explain the phenomenon. He said:

"When it's cold outside, there's hardly any water vapor present in the air, whereas boiling water emits vapor very readily that's why it's steaming. When you throw the water up in the air, it breaks into much smaller droplets, so there's even more surface for water vapor to come off of.
"Now, cold air is very dense, and this makes its capacity to hold water vapor molecules very low. There's just fundamentally less space for the vapor molecules. So when you throw the boiling water up, suddenly the minus 22 air has more water vapor than it has room for. So the vapor precipitates out by clinging to microscopic particles in the air, such as sodium or calcium, and forming crystals. This is just what goes into the formation of snowflakes."
Now, it has to be very cold for this work, so only some of you may be able to perform this trick..."