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No Perfect Crystallizations

Short answer: A snow crystal starts when supercooled cloud droplets freeze onto a tiny particle such as dust or pollen, and then grows as water vapor deposits directly onto the ice. Ice's crystal structure gives it six-fold symmetry, so crystals grow as hexagonal plates, columns or branching stars.

Which shape wins depends on temperature and humidity, so as a crystal tumbles through changing conditions, each stage leaves its mark on its arms. Caltech physicist Kenneth Libbrecht, who grows snow crystals in the lab, explains that complex flakes are almost certainly never identical because of the huge number of possible growth paths, though very simple crystals can look alike, and researchers have grown 'identical-twin' crystals side by side under matched conditions. The footage shows a time-lapse of a crystal growing branches.

VideoWrite-up2 sources

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What should you know about No Perfect Crystallizations?

Quick facts. Each one stands alone and has a stable ID you can cite.

  1. Snowflakes have six-fold symmetry from ice's crystal structure.

    DD-288-F01 · Write-up · Exhibit C (Six-fold symmetry)

  2. Temperature and humidity shape each growth stage.

    DD-288-F02 · Write-up · Exhibit D (Weather shapes it)

Video transcript: No Perfect Crystallizations: Every Snowflake Writes Its Own Flight Log

DID YOU KNOW? Snowflakes form when water vapor in the air freezes onto a particle such as dust or pollen grain. This process called nucleation creates an ice crystal. As the crystal falls through the cloud it encounters more water vapor which freezes onto it in a hexagonal pattern due to the molecular structure of water. The crystal continues to grow and develop intricate, unique shapes as it descends influenced by factors like temperature and humidity. No two snowflakes are exactly alike because of the constantly changing conditions they experience during their formation. NOW YOU KNOW!

Burned-in captions, read frame by frame (see transcript.md) · 26.7s Reel ·

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No Perfect Crystallizations: Every Snowflake Writes Its Own Flight Log Instagram Reel · · 26.7s

The write-up

Every snowflake writes its own flight log. A snowflake's arms record the temperature and humidity it fell through.

  1. Exhibit A

    A seed particle

    Snow crystals start on a tiny particle such as dust or pollen.

  2. Exhibit B

    Growth from vapor

    They grow as water vapor deposits directly onto the ice.

  3. Exhibit C

    Six-fold symmetry

    Ice's crystal structure gives snowflakes hexagonal symmetry.

  4. Exhibit D

    Weather shapes it

    Temperature and humidity decide which shapes grow at each stage.

  5. Exhibit E

    Never quite twins

    Complex flakes are almost never identical, though simple ones can look alike.

Questions people ask about No Perfect Crystallizations

What do snow crystals form on?

It's called nucleation.

Source: Write-up · Exhibit A (A seed particle) · Kenneth G. Libbrecht, Caltech: SnowCrystals.com; Wikipedia: Snowflake

How do snow crystals grow?

The vapor skips the liquid stage.

Source: Write-up · Exhibit B (Growth from vapor) · Kenneth G. Libbrecht, Caltech: SnowCrystals.com

Why are snowflakes six-sided?

Water molecules lock into a hexagonal lattice.

Source: Write-up · Exhibit C (Six-fold symmetry) · Wikipedia: Snowflake

What decides a crystal's shape at each stage?

Each condition leaves its mark on the arms.

Source: Write-up · Exhibit D (Weather shapes it) · Kenneth G. Libbrecht, Caltech: SnowCrystals.com; Wikipedia: Snowflake

Can two snowflakes ever look alike?

Complex flakes are almost never identical.

Source: Write-up · Exhibit E (Never quite twins) · Kenneth G. Libbrecht, Caltech: SnowCrystals.com

Test Your Knowledge

All quizzes →

5 questions, all from this case file. Answers are revealed instantly.

  1. What do snow crystals form on?

    1. A tiny particle like dust or pollen
    2. A raindrop's surface
    3. Lightning
    4. Nothing at all
    Show the answer

    Answer: A. A tiny particle like dust or pollen It's called nucleation. Source: Write-up · Exhibit A (A seed particle) · Kenneth G. Libbrecht, Caltech: SnowCrystals.com; Wikipedia: Snowflake

  2. How do snow crystals grow?

    1. Water vapor deposits onto the ice
    2. Raindrops stick together
    3. They melt and refreeze
    4. Wind sculpts them
    Show the answer

    Answer: A. Water vapor deposits onto the ice The vapor skips the liquid stage. Source: Write-up · Exhibit B (Growth from vapor) · Kenneth G. Libbrecht, Caltech: SnowCrystals.com

  3. Why are snowflakes six-sided?

    1. Ice's crystal structure
    2. Wind direction
    3. Earth's magnetism
    4. Cloud shape
    Show the answer

    Answer: A. Ice's crystal structure Water molecules lock into a hexagonal lattice. Source: Write-up · Exhibit C (Six-fold symmetry) · Wikipedia: Snowflake

  4. What decides a crystal's shape at each stage?

    1. Temperature and humidity
    2. Altitude only
    3. Time of day
    4. The type of dust
    Show the answer

    Answer: A. Temperature and humidity Each condition leaves its mark on the arms. Source: Write-up · Exhibit D (Weather shapes it) · Kenneth G. Libbrecht, Caltech: SnowCrystals.com; Wikipedia: Snowflake

  5. Can two snowflakes ever look alike?

    1. Simple ones can
    2. Never, under any conditions
    3. Always
    4. Only in summer
    Show the answer

    Answer: A. Simple ones can Complex flakes are almost never identical. Source: Write-up · Exhibit E (Never quite twins) · Kenneth G. Libbrecht, Caltech: SnowCrystals.com

Cite this case file

Easterling, Marcus. "No Perfect Crystallizations." The Detail Department (DetailEnjoyer), case file DD-288, last updated Aug 3, 2024. https://detailenjoyer.com/case/no-perfect-crystallizations/

Permalink: https://detailenjoyer.com/case/no-perfect-crystallizations/ · Last updated

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