Frost Ferns on Car Roof

June 30, 2012

Frost Ferns 2 (2)

: Ray Murphy
Summary Authors: Ray Murphy; Jim Foster

On the way to work one morning this past spring in Montreal West, Quebec, I couldn’t help noticing these frost ferns on the roof of my car. The air had been very humid overnight, with little or no wind. This allowed moisture to condense on cold surfaces where it froze when the air temperature dropped just a bit below freezing. Crystal formation and surface patterns of ice are affected by imperfections on the metallic roof surface and the presence of dust and or pollen grains serve as nucleation points for crystalline growth. In the photo, the morning Sun is just starting to shine on my car and melt the lacy frost patterns. Photo taken on April 2, 2012.