Rime Ice

Rime ice is that white stuff that even from a distance doesn't really look like snow and is often covering the top of the blacks on cold mornings when it hasn't snowed. This is what it looks like up close. It's worth clicking this one to see it a little bigger.

According to the Encyclopedia Brittanica, rime ice is, "a white, opaque, granular deposit of ice crystals formed on objects that are at a temperature below the freezing point. Rime occurs when supercooled water droplets (at a temperature lower than 0° C [32° F]) in fog come in contact with a surface that is also at a temperature below freezing; the droplets are so small that they freeze almost immediately upon contact with the object. Rime is common on windward upper slopes of mountains that are enveloped by supercooled clouds. Rime is composed of small ice particles with air pockets between them; this structure causes its typical white appearance and granular structure"