Last Tuesday, November 2, I stopped by the City of Olympia Public Works complex to return the Zero Waste Event containers I had borrowed and, because there is a pocket park at the edge of the parking lot where I pulled in, decided to stroll through the park, whip out my cell phone, and call my mom on the East Coast. Luckily, she was in the mood for a good chin wag, so the call went on for quite a while. Thanks to Washington State's new cell phone laws, I could not get back in my car and drive home while talking, so I just kept strolling around the park among the dwarfish statues of construction workers set among the picnic tables.
And, while I was strolling and chatting and admiring the gorgeous blue sky and fall foliage, a lone cloud appeared (above) to the south at 3:38 p.m. It was a cirrus cloud impersonating a comet--a very slow comet that seemed to not actually be moving. But I kept watching. And watching. And chatting, listening, strolling, and taking pictures of what was happening: as the tufts of this cloud moved across the sky apparently
from west to east, the tail, called a fallstreak, changed its orientation to the tufts--from the 2 o'clock position in the photo at top, counterclockwise to the 11 o'clock position in the photo below, and then to 10 o'clock in the bottom photo.
It's easy to stroll, and chat, snap a few photos, post them here, and say "cool clouds!" It's much harder to explain exactly what was happening. I studied this photo sequence and other cirrus clouds from my field guides to try to tell the story here. Here is what I know: Cirrus are the highest clouds, forming most often at altitudes of 16,500-45,000 feet. They are composed of ice crystals. They will form in a clear sky, as they did here. As I understand them, the ice crystals that form in the fast high winds descend into slower, warmer air and lag behind the "front" tuft of the cloud. If the fallstreaks descend through drier/warmer air, they evaporate and decay. If they descend through moister/cooler air, the crystals grow and the streak expands.
The more I looked at my photos and recalled the movements of the tufts and the streaks, the dizzier I got trying to understand which way was up. From where I was standing near the dwarf with a manhole cover perched jauntily on his yellow hardhat, it appeared that the tuft was moving west to east (right to left in this photo) and that the streaks were moving counterclockwise around the tufts. But I am not sure. The streaks do not look like they are falling--but rising on some invisible current of air.
I went to the Cloud Appreciation Society Cloud Appreciation Society
and looked through 719 photographs of cirrus clouds. All were spectacular, none matched my photos.
And then I search for images on the Internet. Part way through the 4,160 photos, I came across a cloud that was close to mine on WeatherOnline
(below). It captured the spirit of my cloud, but not its singularity,elegance, or cometesque-ness.
Was my cloud unique or was my perspective "off" somehow? I needed help from my friends at the Cloud Appreciation Society. Stayed tuned (as we used to say and some still do) for an explanation.