So what I have been calling hoar frost is not hoar frost. And, no, it’s not whore frost either (which some people think it is). Frost that accumulates in a heavy fog is apparently called rime frost, like that shown below.
Hoar frost forms on calm, clear nights when water vapor in the air undergoes deposition, directly changing from a gas to a solid (ice) on surfaces that are below freezing. This process creates delicate, feathery ice crystals that often resemble ferns or needles. In contrast, rime frost forms in cloudy or foggy conditions when supercooled water droplets in the air freeze onto surfaces that are below freezing. Rime frost typically appears as a more dense, icy coating with less intricate crystal structures compared to hoar frost. The birch tree out front of our home was coated in rime frost because we have had two straight days of fog.
I hope you were paying attention because there will be an exam on this later.
Today’s image from a Canon EOS 7D with a 70-300mm EF IS USM f4.-5.6 lens.
