Intro 

Snowflakes are cool. We see them in fairy lights, arts and crafts projects, and most importantly, winter! But, what are snowflakes?

Prelude to a snowflake

The first question to understanding snowflakes is: how are they formed? In every snowflake, there has to be a nucleus that water droplets can latch onto. This nucleus is usually a dust particle, pollen, or even exhaust from a car. Eating snow might not be as clean as you think — but the particles are far too small to harm you! 

A snowflake requires a very specific set of environmental conditions to be formed. Snowflakes are formed from the moisture in clouds, which is why many snowflakes are formed at or slightly below freezing. Any colder than that, all the moisture in the cloud will freeze, and snowflakes won’t be able to form. In fact, moisture is so important for the formation of a snowflake that the air inside a cloud has to supersaturate in order for one to form. Supersaturation means that there is more water in the air than would normally be possible. When there is too much moisture in the cloud, it will try to get rid of the extra, and some of that extra will latch onto the nuclei from before and turn into snowflakes. 

The famous shape

Why are snowflakes all shaped differently? To answer that, we have to look a little closer —scratch that— a lot closer: we have to look at how the atoms are arranged.

An understanding of snowflakes requires some knowledge of chemistry:  the H2O molecule is made up of two hydrogen atoms and one oxygen atom, and because the molecules share a polar covalent bond, they have a bent shape—commonly referred to as “Mickey Mouse ears.” One end of the molecule (oxygen) has a slightly negative net charge, and the other (hydrogen) has a slightly negative charge. When multiple molecules of the H2O are bonded, the electrical charges begin to pair up, and the resulting shape is a hexagon! Because the shape reflects the molecular arrangement, snowflakes have six sides. 

What makes them unique? 

Have you ever noticed how sometimes snow looks big and mushy, while other times the patterns on individual snowflakes are visible? This diversity can be attributed to the temperature and humidity of the air. For example, at lower humidity, simple hexagonal blocks and plates are formed, while at higher humidity, more branched structures are created. Temperature also affects the way the snowflakes are formed. At 9º F, the branch tips narrow, and at 6º F, side branches sprout.

Because the shape of a snowflake is affected by the weather conditions, every snowflake will be slightly mismatched. As snowflakes fall from different places, they encounter different atmospheric conditions. This graph depicts all the different structures that snowflakes can form based on temperature:

Some fun snowflake facts!

• Snowflakes are like trees: a scientist can tell the weather conditions from when the snowflake first fell based on the growth pattern inside of it. 

• The world record for largest snowflake was recorded on Jan 28, 1887. It was 15 inches wide and 8 inches thick!

• In the U.S, at least 1 septillion ice crystals fall each year — that’s 1 followed by 24 zeros. Snowflakes are not white, but translucent. Because light cannot pass through the ice easily, it’s reflected, giving it snow its signature white color. 

Works Cited

Cappucci, Matthew. “Explainer: The Making of a Snowflake.” Science News for Students, 22 Apr. 2020, www.sciencenewsforstudents.org/article/how-snowflake-made. “Snowflake Facts.” Math, www.softschools.com/facts/weather/snowflake_facts/3208/. 

“How Do Snowflakes Form? Get the Science behind Snow.” How Do Snowflakes Form? Get the Science behind Snow | National Oceanic and Atmospheric Administration, 19 Dec. 2016, www.noaa.gov/stories/how-do-snowflakes-form-science-behind-snow. 

Https://Www.stevespanglerscience.com/Wp-Content/Uploads/2017/07/Steve-Spangler-Science-Logo-435.Png, 21 Jan. 2013, www.stevespanglerscience.com/2013/01/21/the-science-behind-snowflakes/. 

Stevespanglerscience. “The Science Behind Snowflakes.” Steve Spangler Science, Stevespanglerscience

“The Science of Snowflakes, and Why No Two Are Alike.” PBS, Public Broadcasting Service, 22 Dec. 2011, www.pbs.org/newshour/science/the-science-of-snowflakes.