Snowflake Shapes and Patterns

Hexagonal Plates

Hexagonal plates are six-sides flat shapes. The plates may be simple hexagons or they may be patterned. Sometimes you can see a star pattern in the center of a hexagonal plate.

Stellar Plates

These shapes are more common than the simple hexagons. The term 'stellar' is applied to any snowflake shape that radiates outward, like a star. Stellar plates are hexagonal plates that have bumps or simple, unbranched arms.

Stellar Dendrites

Stellar dendrites are a common snowflake shape. These are the branching six-sided shapes most people associate with snowflakes.

Fernlike Stellar Dendrites

If the branches extending from a snowflake look feathery or like the fronds of a fern, then the snowflakes are categorized as fernlike stellar dendrites.

Needles

Snow sometimes occurs as fine needles. The needles may be solid, hollow, or partially hollow. Snow crystals tend to form needle shapes when the temperature is around -5°C.

Columns

Some snowflakes are six-sided columns. The columns may be short and squat or long and thin. Some columns may be capped. Sometimes (rarely) the columns are twisted. Twisted columns are also called Tsuzumi-shaped snow crystals.

Bullets

Column-shaped snowflakes sometimes taper at one end, forming a bullet shape. When the bullet-shaped crystals are joined together they can form icy rosettes.

Irregular Shapes

Most snowflakes are imperfect. They may have grown unevenly, broken, melted and refrozen, or had contact with other crystals.

Rimed Crystals

Sometimes snow crystals come in contact with water vapor from clouds or warmer air. When the water freezes onto the original crystal it forms a coating that is known as rime. Sometimes rime appears as dots or spots on a snowflake. Sometimes rime completely covers the crystal. A crystal coated with rime is called graupel.

How to See the Shape of Snowflakes

It's difficult to observe the shapes of snowflakes because they are tiny and melt so quickly. However, with a little preparation, it's possible to observe the shapes and even photograph them.

1. Choose a dark background for viewing snowflakes. The snow crystals are transparent or white, so their shape shows up best against a dark color. A piece of dark-colored fabric is a good choice because it's portable and rough enough to catch flakes easily.
2. Let the background reach a freezing temperature. Remember, dark colors readily absorb heat. Keep the background out of direct sunlight.
3. Allow snowflakes to drop onto the cold, dark surface. Collect snowflakes falling from the sky. Yes, you can scoop up snow from the ground, but these flakes are most likely broken and may have melted and re-frozen.
4. Magnify the snowflakes so they are easier to see. Use a magnifying glass, reading glasses, or the zoom feature of your phone's photo app.
5. Capture pictures of the snowflakes. Be careful using digital zoom on your phone or some cameras because it often makes the image look grainy. If you have access to one, a camera with a macro lens is your best best.

Sources

• Harvey, Allan H. (2017). "Properties of Ice and Supercooled Water". In Haynes, William M.; Lide, David R.; Bruno, Thomas J. (eds.). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton, FL: CRC Press. ISBN 978-1-4987-5429-3.
• Klesius, M. (2007). "The Mystery of Snowflakes". National Geographic. 211 (1): 20. ISSN 0027-9358.
• Klotz, S.; Besson, J. M.; Hamel, G.; Nelmes, R. J.; Loveday, J. S.; Marshall, W. G. (1999). "Metastable ice VII at low temperature and ambient pressure". Nature. 398 (6729): 681–684. doi:10.1038/19480
• Militzer, B.; Wilson, H. F. (2010). "New Phases of Water Ice Predicted at Megabar Pressures". Physical Review Letters. 105 (19): 195701. doi:10.1103/PhysRevLett.105.195701
• Salzmann, C.G.; et al. (2006). "The Preparation and Structures of Hydrogen Ordered Phases of Ice". Science. 311 (5768): 1758–1761. doi:10.1126/science.1123896