Thursday, December 16, 2010
What's in a snowflake?

Editor's note: CNN Meteorologist Angela Fritz takes a look at how snowflakes are made and why each one is unique. We asked Angela to share her expertise and talk about the mystery of snow after receiving these beautiful, up-close images of snowflakes. Thanks, Angela!

 

Simple prisms, stellar plates, and radiating dendrites might sound like something out of a crazy science experiment, but these are actually some of types of snowflakes we see fall to the ground during the winter time.

 

You might already know that no one snowflake looks the same as another, and that’s true – although each of them do fit a certain type of flake. After an extreme start to winter weather in the U.S., we wanted to take a look at the snowflake itself, and how it’s formed.

 

A snowflake starts with a particle in the air. It could be a piece of dust, a very small grain of sand, or a pollutant from a car. If it’s cold enough, the super-cold water droplets in the air freeze onto the particle, and a snowflake is born. It’s actually very rare that a water droplet will freeze by itself. It actually has to be about 30 degrees below zero in order for that to happen. The particle gives the droplet something to latch onto, and this is the ice crystal that the snowflake will build from.

 

As the crystal falls through the atmosphere toward the ground, it encounters water vapor that freezes onto the crystal, and the flake grows. The type of snowflake depends on how cold it is and how much moisture is in the air. They could look like needles, plates, columns, bullets, or dendrites, which are the traditional six-pointed snowflakes.

 

While the snowflake falls through the air, it could encounter different temperatures and humidities. So a flake that starts off as a plate could quickly start growing in a needle-shape or gain six points on the way down. This is why every flake is individual. The atmosphere is so complex, no two flakes will encounter the exact same conditions at the exact same time on their way to the ground.

 

As the flakes grow and fall through the air, it’s likely they will bump into each other and stick.  This creates the “clumps” of flakes that we sometimes see in heavy snow.  But if you look closely at that clump, you can see all the individual snowflakes within it.  If the atmosphere’s temperature is below freezing all the way to the ground, we will see snow.  But if it’s above freezing where we are, the snowflake will melt into rain and all that hard work will be lost.

12 Comments
December 16, 2010
Click to view sunethra's profile

Having never ever seen a snowflake in my life I enjoyed looking at these real photos of snowflakes, such beauty and delicacy woven in a snowflake with such intricate care, nature's wonders...

December 16, 2010
Click to view tyson's profile

Awesome!

December 16, 2010
Click to view JoyfulGypsy's profile

Beautiful!  I'll be looking forward to some snow so I can try it, too.  Happy holidays.

December 16, 2010
Click to view Bobyouruncle's profile

I have seen a snowflake. What silliness.

December 16, 2010
Click to view thelemonater's profile

I love this story! More snowflake photos, please.

December 16, 2010
Click to view thelemonater's profile

Not everyone has seen a snowflake UncleBob.

December 16, 2010
Click to view Charpy1's profile

Let me get this right.  A snowflake can only begin with a particle in the atmosphere. It could be dust, sand, or even a pollutant from a car.  When it snows, quite a few particles are brought back to earth.  So much for trying to catch a flake with your mouth or eating fresh snow.

December 16, 2010
Click to view Bobyouruncle's profile

thelemonater....I don't live in Africa but I know what a zebra looks like. Google snow flake and knock your self out.

December 16, 2010
Click to view dcshadows's profile

I seem to remember an old book, written over 2000 years ago that said the same thing about no two snowflakes are alike and backed by science to boot.  I don't think that is coincidence..., is it?

 

Merry Christmas!!! to All, 

and to those that are offended Happy Gifts and Presents with pretty paper!

December 16, 2010
Click to view ritemee's profile

Charpy1, The particle (the dust sand..) they talk here is the nucleus of the crystal and it is so small that it will enter in your mouth even when you just open it in the free air.

December 16, 2010
Click to view crussell31's profile

Bobyouruncle, you are being a jerk on purpose. Stop it, people are supposed to be nice this time of year... Merry Christmas to you.

December 20, 2010
Click to view ashleybeise's profile

Merry Christmas!

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