As I was sitting in the parking lot at school today finishing my coffee light snow began. Soon it changed to a wind whipped graupel for about 5 minutes. It ended as I was walking to the building.
I knew what graupel was, having seen it a very few times before, but I realized I didn't know how if formed. Thinking I might discuss it with my students I looked it up. Snowflakes that accrete with supercooled water droplets, very cool. It leads me to ask if this is one of those things we think we know, or are we confident in our understanding of this phenomenon.