Category: "Hoar frost"

Hoar Frost on Plastic

February 17th, 2020
The pattern of hoar frost depends on not just the current and prior conditions, but also on the surface. If the surface is less attractive to water, that is, more hydrophobic, then the hoar crystals tend to be more further spaced apart. Or even more… more »

The Curious World of Ice and Snow: Part 1 of 3

February 4th, 2020
In 2012, I gave a "science cafe" talk with a local series sponsored by the Pacific Science Center, KCTS public television, and Science on Tap. The title was "The curious world of ice and snow". The location was a bar in Kirkland, but open to all ages.… more »

Martini Hoar (raise a tiny glass?)

October 19th, 2019
The hoar-frost crystal shoots up like a thin, solid straw, then suddenly opens up into a cup-like shape. I have seen it often enough to give it a name: "martini hoar". The cup can be weirdly segmented and polyhedral, but it nevertheless widens suddenly.… more »

Puddle gets its grooves (upon freezing), part I

February 16th, 2019
These grooves appear on the surface of frozen puddles. [image:111] Most grooves are straight lines, and most of these also appear to have relatively symmetric sides, such as those marked #s 1, 2, & 4 in the above image. But some, such as #3, have… more »

Film frost grains and radiative cooling of the ground

December 10th, 2017
December 8th brought the first frost to the Seattle area. This doesn't mean that this is the first time this season that the ground reached 0 degrees C or lower. True, we had gotten snow in late November, though this by itself doesn't mean the ground… more »

Concentric Film Frost

October 25th, 2017
October 16, 2017, the first frost of the 2017-18 winter as far as I know. Frost in Eastern Washington anyway, those of us on the west side of the Cascade Mts have not gotten any yet. Marc Fairbanks, an avid nature observer from the mountains near Cle… more »

Glaze-rime Ice Buildup Facing Creek

November 23rd, 2014
Here's a reed of some sort, with a glaze of clear rime on the side facing a creek. How did the clear ice get there, and what is the white ice on top of it? The fact that the clear ice is just on the side facing the creek indicates that the ice came from… more »

A Change in Habit

November 23rd, 2014
The two main growth modes of snow and hoar (i.e., ice growth from the vapor) are columnar and tabular. In columnar, the shape is long and thin, like a pencil or cluster of pencils (bound snugly with a rubber band). In tabular, the shape is plate-like or… more »

Smaller Hoar Growing on Larger Hoar

November 22nd, 2014
Cold air came down the interior, spilling through gaps in the Cascades, cooling the western side. In the Seattle area, we got our first frost on Nov. 11, but the days stayed cold. Areas in the shade never lost their hoar, so the hoar frost kept growing.… more »

Crystal-to-crystal “communication” through vapor and heat

January 5th, 2013
Two mornings ago, I saw this on the windshield of a parked car. The bulls-eye pattern wasn’t centered on any particular feature on the windshield, and there were similar, though less developed, patterns nearby. See them on the photo below. The dark… more »