By: Donald Szlosek
Do you ever look out your car window and notice the intricate design of a snowflake? Have you ever wondered how snowflakes are formed and whether they really are truly unique?
First off, the formation of ice crystals, more formally known as snowflakes, takes place in the lowest portion of the Earth’s atmosphere, known as the troposphere. This region contains 99% of the atmosphere water vapor and aerosols (such as pollutants and dust particles).
In this region water maintains its gaseous form at temperatures as low as -40C. Some water molecules start to aggregate loosely, but then fall apart due to the turbulence in their environment. Snowflakes will only form if there are some dust particles floating around in the air. These particles act as crystallization seeds, allowing the water molecules to bind and start aggregating to a solid surface.
Wait, does that mean the snowflakes are not purely water?
Yes, infact snowflakes can only occur when there is an interaction between vaporized water and dust particles. All other frozen water droplets are called sleet.
Sure, this is how ice crystals start to form, but what about their intricate patterns? For this we have to look down at the atomic level.
Water is made up of one part negatively charged oxygen and two parts positively charged hydrogen. Thus water is polar, meaning part of the molecule has a negative charge while the other has a positive charge. This causes water molecules to have a bent shape. Snowflakes are symmetrical (or patterned) because they reflect the internal order of the crystal’s water molecules as they arrange themselves in predetermined spaces (known as “crystallization”) to form a six-sided snowflake. Thus every ice crystal you see will have six sides due to the electronic properties water molecules.
As the hexagonal lattice forms, it gets lifted higher by turbulence, (much like when you rise up after opening a parachute). After reaching a certain size, they begin to fall again. Every snowflake forms differently depending on the temperature and humidity of their respective air layers they are floating across. Thus every snowflake is structurally different in the formation of their ice crystals. So the next time you see it snowing outside, take a look at a snowflake and see how truly unique they are.
Donald Szlosek did his undergrad at USM Majoring in Human Biology with minors Physics and Biochemistry and is currently a graduate candidate in the MPH program focusing in biostatistics and epidemiology.