How do snowflakes form?
Here is a wonderful site about snowflakes: http://www.its.caltech.edu/~atomic/snowcrystals/ it even teaches you how to make one!
It turns out that “pure” snow is made up of snowflakes which are made up of from 2 to 200 separate snow crystals. Snow crystals are crystals that have formed around tiny bits of dirt that have been carried up into the atmosphere by the wind. So snow crystals are really soil particles that have been dressed up in ice. Scientists think that there are really four different shapes of snow crystals. The simplest shape is a long needle shaped like a spike. The other shapes all have six sides. One of them is a long, hollow column that is shaped like a six-sided prism. There are also thin, flat six-sided plates. And lastly there are intricate, six-pointed stars. The shape that a snow crystal will take is dependent upon the temperature at which it was formed. The temperature in the highest clouds is around -30°F and they are made up exclusively of ice crystal columns. The other three shapes are formed in a narrow temperature range. When the temperature in the clouds is 3° to 10°F the star shape
Snowflakes are the result of symmetrical crystallization of water molecules as they turn into ice crystals. Water molecules, when pass to crystalline solid state, such as in ice and snow, form weak bonds (called hydrogen bonds) in which two hydrogen atoms tend to attract neighboring water molecules.
Every snowflake is a collection of snow crystals. Snowflakes can consist of only 2 snow crystals or hundreds of snow crystals. Snow crystals are frozen water molecules which bond to each other. Snowflakes are formed when Snow Crystals grow into tiny, sometimes microscopic, “symmetrical” shapes. “Symmetrical” means: proportional, or having an equal number of parts. A perfectly formed 6-sided snowflake is called “symmetrical”.
