Snowflakes (snow crystals) are collections of frozen ice crystals. Ice crystals freeze around small particles of dust in the atmosphere. As the ice crystals fall to the ground, they join together, forming snowflakes. The shape that each snowflake takes is determined by the wind, temperature, water vapor in the atmosphere and the time it takes the snowflake to get to the ground. The following outlines some facts about snowflakes.
Snowflakes (collection of ice crystals)
Snowflake is a general designation for a cluster of individual ice crystals. Typically, ice crystals aggregate together during a snow storm, forming snowflakes. Each ice crystal has its unique design and structure; however, the best known types are the Dendrite Star, Columns, the Star Crystal, Capped Columns, Needles and Irregular Forms. Ice crystals are six-sided because water molecules have six sides and extend in six different directions. A snowflake can be formed by two or a great number of snow crystals.
Snowflakes form in the clouds from single ice crystals of water vapor. The ice crystals gather numerously in the atmosphere and arrange in symmetrically elaborate patterns. The temperature in the atmosphere must be below 0° C (32° F) for the water vapor to turn into crystals. As the snowflake leaves the cloud on its way to the surface of Earth, it can pass through various layers of varied temperatures and humidity which will cause them to go through various structural variations.
Ice crystals arrange themselves symmetrically, reflecting the internal structure of water molecules. Water molecules in the solid state (ice and snow) form hydrogen bonds with one another. This results in the hexagonal (six sides) shape of the snowflake. During the process of crystallization, the water molecules align together to form a crystalline lattice. It is the hexagonal crystalline symmetry that in the end determines the shape of the snowflake.
Individual snowflakes are characterized by their uniqueness and structure. As individual snowflakes fall from sky, they follow different paths to the ground, encountering a variety of atmospheric conditions, including wind, temperature, and humidity, which is what determines their characteristics and structure. In addition, the time it takes for them to touch the ground determines an array of molecular arrangements in their structure. For two snowflakes to be identical, they would have to follow similar paths through analogous atmospheric conditions.
Snowflakes go through various shape changes at varied temperatures and water vapor super saturation conditions. What determines their size and shape is temperature changes in the atmosphere. In a 1° C (30° F) temperature, snowflakes are usually columns. In a -2-5° C (27-23° F) snowflakes look like needles. In a -5 to -7° C (23-18° F), snowflakes take a column form again. In -7 to -12° C (18-10° F), snowflakes take the form of a plate. In -12 to -16° C (10-3° F), snowflakes are normally shaped like a star. The size and shape of snow crystals varies dependent on the sensitiveness of crystals to temperature changes.
Snowflake as a symbol:
The snowflake has been used as a seasonal symbol in the Christmas period, especially in the United States and Europe. During Christmas it is very customary to make paper snowflakes manually by folding paper sheets and cutting symmetrically through it. A snowflake was used as the symbol of the 2002 Winter Olympic Games in Salt Lake City Utah. In 1999, the U.S. Rubber Manufacturer Association (RMA) and the Rubber Association of Canada (RAC) agreed on a mountain/snowflake symbol on the tire sidewall to identify tires that provide a higher level of snow traction.