# No Perfect Crystallizations (DD-288)

> 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.

- Department: Nature (also Science)
- First published: 2024-08-03
- Last updated: 2024-08-03
- Permalink: https://detailenjoyer.com/case/no-perfect-crystallizations/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## Quick facts

- **DD-288-F01**: Snowflakes have six-fold symmetry from ice's crystal structure. _(Write-up · Exhibit C (Six-fold symmetry))_
- **DD-288-F02**: Temperature and humidity shape each growth stage. _(Write-up · Exhibit D (Weather shapes it))_

## Write-up

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

1. **A seed particle**: Snow crystals start on a tiny particle such as dust or pollen.
2. **Growth from vapor**: They grow as water vapor deposits directly onto the ice.
3. **Six-fold symmetry**: Ice's crystal structure gives snowflakes hexagonal symmetry.
4. **Weather shapes it**: Temperature and humidity decide which shapes grow at each stage.
5. **Never quite twins**: Complex flakes are almost never identical, though simple ones can look alike.

## Related case files

- [Hail Storming (DD-633)](https://detailenjoyer.com/case/hail-storming/): I paired it with the other kind of ice that falls from clouds
- [Ruby Red (DD-167)](https://detailenjoyer.com/case/ruby-red/): I linked more about how crystals form
- [Opulent Opal (DD-169)](https://detailenjoyer.com/case/opulent-opal/): I linked more about minerals
- [Exceptionally Emerald! (DD-170)](https://detailenjoyer.com/case/exceptionally-emerald/): I linked more about crystal flaws

## Reel vs. record

- **Note**: 'No two snowflakes are exactly alike': I'd soften this a little. It's true for complex flakes, but tiny simple crystals can look alike, and researchers have grown near-identical twins in the lab.
- **Note**: 'Water vapor freezes onto a particle': close. In clouds a supercooled droplet usually freezes on the particle first, and vapor then deposits onto the ice.

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

- Duration: 26.7 s · Published: 2024-08-03
- File: https://detailenjoyer.com/assets/videos/C-OsB5YJY3G.mp4

### Transcript

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!

## Questions & answers

**Q: What do snow crystals form on?**  
A: It's called nucleation. _(Source: Write-up · Exhibit A (A seed particle) · Kenneth G. Libbrecht, Caltech: SnowCrystals.com; Wikipedia: Snowflake)_

**Q: How do snow crystals grow?**  
A: The vapor skips the liquid stage. _(Source: Write-up · Exhibit B (Growth from vapor) · Kenneth G. Libbrecht, Caltech: SnowCrystals.com)_

**Q: Why are snowflakes six-sided?**  
A: Water molecules lock into a hexagonal lattice. _(Source: Write-up · Exhibit C (Six-fold symmetry) · Wikipedia: Snowflake)_

**Q: What decides a crystal's shape at each stage?**  
A: Each condition leaves its mark on the arms. _(Source: Write-up · Exhibit D (Weather shapes it) · Kenneth G. Libbrecht, Caltech: SnowCrystals.com; Wikipedia: Snowflake)_

**Q: Can two snowflakes ever look alike?**  
A: Complex flakes are almost never identical. _(Source: Write-up · Exhibit E (Never quite twins) · Kenneth G. Libbrecht, Caltech: SnowCrystals.com)_

## Sources

- [Kenneth G. Libbrecht, Caltech: SnowCrystals.com](https://www.its.caltech.edu/~atomic/snowcrystals/)
- [Wikipedia: Snowflake](https://en.wikipedia.org/wiki/Snowflake)

## 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/