Bending of branch and pond

February 11th, 2014
Bending bending bending                 The fir branches are bending                 They are waiting for more snow The famous Japanese poet Basho wrote a poem like the above, except it was about bamboo bending under the snow load. I was… more »

Hoar that grows down and out

February 9th, 2014
It had been a continued spell of cold days and nights, the ground snow-free, the air clear and dry. No film-frost on the cars in the morning, and no spikes of hoar frost sticking up on grass or post. The only signs of ice had been the frozen pond and… more »

One hundred twenty one forms of falling ice: the new snow classification system

January 22nd, 2014
When I last wrote about the classification of falling snow and ice (02/14/2010), I discussed the 1966 Magono-Lee system. At the time, this system was the most recent one, and as such, the one generally used in meteorology. And to those who wondered how… more »

2013 Snow Crystal Photos

February 8th, 2013
  In the last few weeks, the winter of 2012/13 has been pretty good for snow crystal photos. Below is one sample, and you can see a full set of this season's photos on my flickr account -… more »

What makes the thick curvy lines in frozen puddles?

January 27th, 2013
My sister recently sent this photo of a frozen puddle, a little over a foot across. Something broke out a piece of ice in the upper right, but it’s mainly a complete glaze over the top. (The white dots are rimed snow crystals. Click to zoom in and see.)… more »

Rime falling from branches

January 24th, 2013
While riding my bike home the other day, I saw what appeared to be a patch of light snow. It was the only such patch around. Looking closer, I could see that it consisted not of snow, but of chunks of partly melted rime deposits. (Note how the pieces… more »

Rime, freezing fog, and crystalline spider webs

January 22nd, 2013
The Pacific Northwest has been foggy a lot lately, but the fog droplets have been subzero, or supercooled. When such fog droplets hit an object, they almost always freeze. The resulting frozen aggregate is called rime. Freezing fogs make rime. The… more »

Frost Days and Ice Days: Declining Numbers over the Century

January 17th, 2013
David Easterling recently reported in BAMS** that the number of frost days per year is decreasing over the US. A frost day is a day in which the minimum temperature goes below the melting temperature of ice (32 F or 0 C). This doesn't sound good for a… more »

Hair Ice on Wood and Pavement

January 16th, 2013
The morning after a rapid cool-down, I found hair ice on an alder log. From a distance, it looked unnaturally white, like it was a bit of discarded cotton or white paper, but the closer I got to it, the more incredible it seemed. 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 »