Physics is Beautiful
And if you don’t believe it, just read the physics of how a snowflake forms as written by the Snowflake-Man himself, Don Komarechka.
Originally shared by Don Komarechka
Snowflake-a-Day #7
Ever wonder why snowflakes have six sides? Not 8, not 5, but always six (unless it’s broken or malformed). Even on the smallest scale snowflakes are hexagonal, which is where it all starts. View large!
Snowflakes like this one start as a column. You might be able to see a remnant of that in the center, depicted as a circle. This is a shaft of ice connecting the top hexagon to the bottom branches. Why circular? It would have originally been hexagonal, but that particular region of the crystal does not receive any new water vapour, and the shape of the center column will degrade due to sublimation.
The molecular lattice that water molecules form is roughly hexagonal in nature, which echoes the shape of the smallest observable snowflakes. They are hexagonal because that’s the easier shape for water to crystalize in. There is a very simple rule that follows, and it’s the main reason why snowflakes grow in the shapes they do:
Whatever sticks out the farthest, grows the fastest. Imagine that tiny hexagonal crystal? The corners stick out more than the sides, and this evokes the “branching instability”. The corners will grow at an accelerated rate compared to the inner areas, and once they start to move beyond the tiny hexagon, their growth accelerates. Variations in humidity and temperate play a part in how the water molecules attach themselves and at what rate, but they always grow the fastest where there is more access to water vapour.
This same logic allows for bubbles to form in the ice. The thin edge of the snowflake that grows outward is subject to the same physics. The top and bottom edge might grow slightly faster that the inner area of the facet, and a cavity can form there. Changing environmental variables can cause that cavity to open further or to close itself off, creating interesting internal crystal details.
The physics of how snowflakes form is rather simple, and it’s easy to spot the evidence of the simple rules that govern it. There are many more factors at play than just the branching instability, but that alone helps you identify the history of each crystal.
For more physics and a comprehensive photographic tutorial, check out Sky Crystals: https://skycrystals.ca/book/
And for a print containing five years of work (over 2500 hours) on the subject, you need to check this out: https://skycrystals.ca/poster/
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