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Hey folks, it's that time of year when some of us are hoping for a winter
holiday blanketed in white, while others are already sick of dealing with the
slushy stuff. Love snow or hate it, here's a collection of our favorite snow
chemistry, not just how it forms but how to deal with it too. First up here's how
freezing water creates those beautiful delicate flakes of snow and why no two
are truly alike. A snowflake starts as a dust grain floating in a cloud. Water
vapor in the air sticks to the dust grain and the resulting droplet turns
directly into ice. Crystal faces appear on the frozen droplet, then a prism forms
with six faces and a top and bottom. A cavity forms in each prism face because
ice grows fastest near the edges. Faster growth on the corners causes six
branches to sprout. The lines in each branch are due to ridges and grooves on
the surface. These six branches form the corners of a hexagon which occurs
because the water molecules chemically bond into a hexagonal network. When the
temperature cools to minus 13 Celsius, new growth at the branch tips narrows. At
minus 14, side branches sprout on each branch. Suddenly the crystal encounters a
quick blast of warmer air followed by cooler air and more side branches sprout.
The crystal gradually warms, making the tips long and narrow. The crystal
encounters even warmer air which slows the growth and widens the tips. Finally
this unique and delicate structure falls to the earth along with countless other
snowflakes. Cool right? But what if you really need a winter wonderland and the
weather just isn't cooperating? No need to fear. We can fake it! Artificial snow
forms the same way as regular snow as long as we can manage to mimic nature's
exacting conditions. To make artificial snow, water cooled to just above its
freezing point is pumped under high pressure through the nozzles of a snow
gun. This thing blasts water and nucleating agents 20 to 30 feet in the
air. The tiny nozzles in these snow guns
break up the water into a super fine mist and fans or compressed air help keep
water particles afloat much longer to make sure they freeze before they hit
the ground. Also the compressed air expands when
released, thus dropping its temperature alongside the temperature of the water
particles. Another important component to making snow is to make sure that you've
got the right combination of temperature and humidity.
Lower humidity means that snow can be formed at higher temperatures. With
untreated water, a temperature of about 18 degrees Fahrenheit or about negative
8 degrees Celsius is needed. If the temperature isn't cold enough, added
materials are used for the nucleation. Just like with real snow, nucleating
agents are extremely important for artificial snow. So in modern snow guns
there are a lot of different types used including silver iodide or proteins made
by special bacteria. Artificial snow is great for skiing or a bit of fun for
the kids, but what if you're trying to get to work in the morning? We've got a
bunch of life hacks for managing the wintry chill including why kitty litter
is your car's new best friend. Your car is stuck in the snow and can't get any
traction on the road? Kitty litter to the rescue. Clay kitty litter is super useful
in the winter because it helps produce a surface that your tires can catch
traction on. Just throw the kitty litter down in areas where your tires are
struggling. Basically what's happening is your car tires can't catch any grip due
to either the slipperiness of the snow and ice or from hydroplaning the slush.
Kitty litter takes on water like a champ, including all the excess water created
by the friction of your spinning tires. And as it does so it expands, eliminating
the muck of slush that keeps you going nowhere. This offers your tires a
regular surface to grab on to, hopefully leading to your safe escape.
If you live anyplace icy enough, you know that salt scattered over
sidewalks and roads seriously improves the slippery
situation snowstorms can create. Salt actually changes the freezing point of
water. Here's how it works. Turns out salt isn't actually about
melting. It's all about freezing. So the freezing point of pure water rests at 32
degrees Fahrenheit or zero degrees Celsius. When the temperature of water
reaches the freezing point, its normally free-flowing molecules get
trapped into organized crystal structures. This is how ice is formed.
Salt disrupts this process. Upon hitting water, salt breaks up into two ions: one
sodium and one chloride. These two ions then move around and take up space in
between water molecules, pushing them apart and frustrating their potential
links to form ice. This disruption is called freezing point depression. And so
to put this simply, salt lowers the freezing point of water. I'd like to
thank chemistry for keeping me from face-planting on the sidewalk every
morning in January. That's all for now. If you'd like to learn even more about
snow and ice, check out the links to the full videos below. Thanks for watching
and if you can still feel your fingers after this chilly compilation, use them
to hit that subscribe button, and switch on notifications to see all our videos.
Each one special as a snowflake. We'll see you next week.