Wednesday, December 06, 2017
Have a frosty Corona!
Freezing fog can take all sorts of forms, but this morning's version is unique. Every blade of grass, every plant stem, and every chainlink fence, is coated with half-inch long frost thorns. Flat surfaces like cars and streets and trashbins have a light patchy coating of flat frost.
Is it the smallness of the objects? No, it's exactly the curvature that matters. I noticed this neatly on a neighbor's Xmas decorations. The annoying display includes a giant fake 'ribbon' tied in a bow with several sharp bends and several flat areas. The flatter parts of the ribbon were uncoated, and the fake wrinkles had thorns. Good experiment.
Here's a less impressive picture, taken at 11AM after it started to melt. You can see the thorns on the edge of the trash bin, and none on the flat or curved parts. The rule seems to be that every curve with a radius less than 1/2 inch gets thorns.
It's a frost corona!
¶ 11:43 AM 
Is it the smallness of the objects? No, it's exactly the curvature that matters. I noticed this neatly on a neighbor's Xmas decorations. The annoying display includes a giant fake 'ribbon' tied in a bow with several sharp bends and several flat areas. The flatter parts of the ribbon were uncoated, and the fake wrinkles had thorns. Good experiment.
Here's a less impressive picture, taken at 11AM after it started to melt. You can see the thorns on the edge of the trash bin, and none on the flat or curved parts. The rule seems to be that every curve with a radius less than 1/2 inch gets thorns.
It's a frost corona!
¶ 11:43 AM
