One of the common forms of snow happens when the warmer lake's air mixes with a cooler air mass. The resulting snow is called Lake Effect Snow, it is characterized by rapidly growing crystals that are basically formless spheres and elongated masses. Once the crystals can form they fall through warmer air and build up ice under different crystal orientations. The opposite is also true - where warmer ice can fall through a cooler layer and an ice crystal starting in an ugly mass can start to grow the perfect dendritic arms. Snowflakes can also fall through layers of different relative humidity where they can both build up and lose mass.
Ice can also sublimate.
Here in New York, I estimate that we get 15 good storms when it is both cold enough to photograph and there is good snowflake development. Due to my proximity to the Great Lakes, there are a number of snowflake types that are either very rare, or just do not form in this location. These include the very cold forms, and the top-hat shapes. You can basically think about photographing a snowflake as being identical to optically testing a small piece of glass or micro-lens for defects. Dendritic, 10x objective.