Frostflakes


After an evening of 5-10 degree temperatures and following some heavy snow, the valleys in the SW VA Blue Ridge had a magnificent frosting event. The crystals of frost grew large and heaved themselves into upright positions. I found these on top of my car.

Immediately I was struck by how some of the frost growth presented itself as perfect crystals...identical to individual snowflakes. There was one significant difference...size. These "frost flakes" were twice the size of the snowflakes I witnessed a couple of weeks ago. I estimate the frost to be between 1/4" -1/2" in total crystal width. The snowflakes were tiny...always less than 1/4" wide.
And so, I am left with questions:
  • Why is there such a similarity in crystal structure and appearance and yet a difference in size?

  • Were these frost crystals permitted a greater amount of time for growth (and thus grew larger)?

  • Could they have grown at a slower rate under sustained conditions?

  • Given that water is a mineral, is it likely that its crystal growth behaves similarly to that of other minerals like sugar, salt, emerald, quartz, pyrite, to name a few?

  • What are the conditions for optimal water crystal growth anyway??

By the way, for you rockhounds out there: Water is technically a mineral, and rocks are defined as being a mixture of minerals. So, if one were to accidentally scoop up a little sand, silt, or other mineral while creating a snowball (inevitable), presto! Yes, technically, snowballs are rocks, and a local geologist agreed with this logic ...the same can be said for glaciers and muddy rivers. I suspect a distinction can be made with relationships between particles however. Rocks usually contain fused minerals, rather than suspended. But, if this distinction does not play a role in defining rocks, the comparison still stands (and awaits the onslaught of more knowledgable folk). So the next time you get hit in the head with a snowball, and it feels like a rock...well, it probably is.