Big flakes, small flakes
No, we’re not talking about social ineptitude but rather the size of the snow flakes coming down around us. Did you ever wonder about why some days the flakes seem tiny and yet other times they are enormous?
In fact, the size of the flakes are a signal about how much moisture is in the air above us. The famous work of Wilson Bentley over a century ago detailed the various types of flakes and his estimation that no two are alike. Perhaps that is true but there are certain similarities including the fact that all snow crystals start out with six sides.
What happens as they travel through miles of the atmosphere before finally arriving at the backyard as a snow flake depends on how much available water vapor is present and the temperature of the various layers of the air. If there is a great deal of moisture and the temperature is near the freezing mark they will pick up more moisture making them stick together should they bump into one another on the ride down.
On the other hand if the air is relatively dry then they will remain separate and smaller. The end result is what we who are trying to clear the sidewalk might call either a dry snow with small individual fluffy flakes or a wet, heavy and moisture laden event. Either way, it will turn back to liquid eventually.