Different snowflakes (noaa.gov)
Characteristics of
snowflakes
- Made of ice crystals - At an
appropriately cold temperature, when water droplet in the
atmosphere freezes on a particle, an ice crystal (primary)
is formed. Snowflakes are formed when frozen water vapor
freezes on the primary crystal to form the arms, shape,
and patterns.
- Different shapes and patterns - The
shapes and patterns of snowflakes are determined by the
atmospheric temperature and moisture.
- No two are the same - Each follow different paths as they fall from the sky, thus encountering different atmospheric conditions, which plays a role in their shape formation.
- Symmetrical: The symmetry of snowflakes are reflected by crystallization, which is the established and most efficient structure for water molecules.
- Hexagonal (six-sided)
- All snowflakes have size sides because of
crystallization.
When ideal atmospheric
conditions such as freezing temperatures--at or below 32
Fahrenheit or 0 Celsius--and humidity are acquired, air
droplets begin freeze into primary ice crystals. As the
primary ice crystals travel down from the sky towards the
ground, water vapor freezes on the primary crystal. However,
as it moves further down, it is subjected to the atmospheric
conditions in that level, which dictates its eventual shape
and pattern. Note that all snowflakes have six sides or arms;
this is driven by water's most efficient arrangement.