Snow crystal guide

The Nakaya diagram

In the 1930s, Japanese physicist Ukichiro Nakaya proved that snow crystal shape depends on temperature and humidity in the cloud where they form.

• 0 to -3°C: thin plates and simple prisms.
• -3 to -8°C: needles.
• -8 to -22°C: dendrites (classic snowflake). Peak around -15°C.
• -22 to -40°C: plates and columns again.
• -40°C or colder: rare form types (cross-shaped crystals).

Higher humidity produces more complex, feathery shapes.

The main crystal types

The six-fold symmetry

Snow crystals almost always have six-fold symmetry.

1. Water molecules have angles based on H-O-H bond geometry (104.5°).
2. When water freezes, molecules pack in hexagonal lattice.
3. Growth follows lattice symmetry.
4. Same environmental conditions on all six arms produce identical growth.
5. Result: six-fold symmetric crystal.
6. Occasional exceptions (twelve-branched crystals from twinned nuclei).

Why no two are alike

Even though shape follows rules, no two snowflakes are truly identical because:

• Each falls through slightly different air.
• Randomness in molecular attachment.
• Number of water molecules in typical crystal: 10^18.
• Number of possible arrangements: astronomical.
• 2007 study argued IDENTICAL crystals may exist statistically, but never observed.
• Kenneth Libbrecht at Caltech has grown very similar crystals in lab.

The Bentley photographs

Wilson Bentley, a Vermont farmer, photographed 5,000+ snow crystals from 1885-1931.

• Self-taught. First photographs of individual snowflakes.
• Died of pneumonia contracted photographing his final snowstorm.
• His book "Snow Crystals" is a classic.
• His collection is at Buffalo Museum of Science.
• His pioneering work established that all snowflakes are unique.

Modern snow crystal research

• Kenneth Libbrecht (Caltech) has grown crystals in temperature-controlled chambers.
• Confirmed and refined Nakaya diagram.
• His book "The Snowflake" is authoritative modern text.
• Predicted crystal types not naturally observed.
• Ice physics is still being refined at cutting edge.

Where to see the best snowflakes

• Very cold temperatures (below 15°F) produce cleanest crystals.
• Little wind (crystals fragment in high wind).
• Rural areas (low pollution).
• Northern regions (Michigan, Vermont, Alaska).
• Wilson Bentley photographed in Jericho, Vermont.
• Photography: dark background, magnifying glass or microscope.

Photographing snowflakes

1. Very cold black surface.
2. Catch snowflake with black card.
3. Move quickly — melts within minutes at anything above 20°F.
4. Macro lens (100mm+).
5. Focus stacking essential.
6. Ring flash or LED for controlled lighting.
7. Multiple exposures at different focal points.
8. Composite in Photoshop.
9. Best on days below 15°F.

Snow crystals in art and culture

• Bentley's photographs inspired art nouveau design.
• Modern snowflake designs on holiday decorations.
• Six-pointed star symbolism.
• Cultural weight in Northern regions.
• Frozen (2013) — Disney film based partly on snow crystal geometry.
• Frozen 2 (2019) — continues theme.

The snowflake and society

'No two snowflakes are alike' is used metaphorically for individual uniqueness. Ironically:

• Snowflakes DO follow strict physical rules.
• They're only unique because randomness is astronomical.
• This may or may not be relevant to human individuality.
• The metaphor is charming regardless.

Learn more

• Snowstorm vs blizzard vs whiteout
• Snowfall forecast explained
• Ice storm safety
• Cloud types illustrated