how snowflakes form, snowflake science, snow facts

The Science Behind Snowflakes

Read Time: 4 minutes

Everyone always hopes for a white Christmas, with snow covering the ground. The cold white stuff is falling in most of the Northern Hemisphere, but where do snowflakes come from? Why is each snowflake unique? Let’s take a closer look at how snowflakes form along with the science of a snowflake.

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The Origin of Snowflakes

When it’s cold outside and there are clouds in the sky, everyone is on the lookout for snowflakes. Where do they come from, though, and how do snowflakes form? Each one started its existence as a droplet of water inside a cloud. Instead of condensing into a raindrop and falling to Earth, if temperatures are low enough, it will condense directly into ice and becomes an icy seed crystal. These seed crystals are too small to be seen with the human eye — they can only be observed under an electron microscope.

As seed crystals fall, they start to collect moisture from the air around them. If temperatures are low enough — and humidity is high enough — they’ll begin to form into the snowflakes you know, love and enjoy catching on your tongue.

It’s important to note that snow isn’t just frozen rain. A rain that freezes as it falls is called sleet.

Each Flake Is Unique

No two snowflakes are alike. You can catch two flakes in the same location, and they’ll still have subtly different shapes — a snowflake’s shape is dependent on the weather conditions as it falls. Higher humidity, when paired with lower temperatures, will create more elaborate forms. Higher temperatures will lead to flat hexagonal flakes without the delicate details that we’ve come to expect from a snowflake.

Upper levels of the atmosphere are often turbulent, especially during stormy or snowy weather. The more a flake is blown around, the more different atmospheric conditions it can encounter, changing the shape of the crystals as they form. That’s also why you can catch two flakes that look nothing alike. One of them may have fallen from the cloud directly above you, while the other may have been carried by winter winds for miles before it finally became dense enough to land.

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Why Six Sides?

Even though snowflakes all appear to be unique, they have one thing in common — every individual snowflake that you find will have six sides.

This makeup is because of the inherent crystalline structure of the ice — and the way the atoms in water molecules align themselves. A single water molecule is made up of three atoms — two of hydrogen and one of oxygen. When these molecules come together to form a water droplet, they create what is known as a covalent bond. The atoms are similar, so they’re able to share electrons. When water molecules form droplets, they align themselves in a hexagonal or six-sided shape.

This shape won’t apply to ‘snow puffs,’ which occur when multiple flakes form into one more massive puff and fall together.

Not as Symmetrical as They Look

At a glance, a snowflake might seem like one of the few perfectly symmetrical things in the world, but if you observe it more closely, you’ll find that they aren’t as symmetrical as they look.

Most snowflakes will grow evenly on all sides, but a collision with another flake that doesn’t result in the creation of a snow puff — as well as certain atmospheric conditions — can keep a snowflake from forming evenly. It doesn’t make them any less beautiful — it merely changes the crystalline structure to make the flake a little less symmetrical.

preparing for snow

Preparing for Snow

When you get a lot of snowflakes together, they can cause problems, so it’s important to be ready for the inevitably snowy winter season. Having an emergency kit with food, water, lights, first aid and other supplies is always a good thing, regardless of the season, but it could prove to be life-saving during a winter storm.

If your power goes out on a regular basis during the winter, it’s also a good idea to invest in alternative sources of heat and energy for the duration of the storm. A fireplace can provide heat and light, as long as the chimney is well maintained and proper fire safety measures are taken. For power, a portable generator that runs on gasoline or diesel can be a useful tool.

The most important things to remember when it’s snowing outside are that you need to stay hydrated, warm and dry during the storm. Everything else can wait until the utility companies restore power to your home.

You’ll likely never see two snowflakes in your life that look alike. Now you have a better idea of the science of snowflakes and how they from — think about that the next time you go out to have a snowball fight or build a snow angel. Every flake on the ground looks the way it does because water molecules happen to come together in a hexagonal shape, creating the perfect winter wonderland with crystalline geometry.

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Category: Everyday Science


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Article by: Megan Ray Nichols

Megan Ray Nichols is a freelance science writer and science enthusiast. Her favorite subjects include astronomy and the environment. Megan is also a regular contributor to The Naked Scientists, Thomas Insights, and Real Clear Science. When she isn't writing, Megan loves watching movies, hiking, and stargazing.